JP6522395B2 - Polyimide film, flexible metal-clad laminate, and method of manufacturing flexible printed wiring board - Google Patents

Description

  The present invention is a polyimide film capable of suppressing a crack generated in a process of forming a circuit while continuously conveying a flexible metal-clad laminate by roll-to-roll, a flexible metal-clad laminate having a polyimide film and a metal foil. And a method of manufacturing a flexible printed wiring board.

  2. Description of the Related Art In recent years, high performance, high functionality, and miniaturization of electronic devices have rapidly progressed, and along with this, demands for miniaturization and thinning of electronic components used in electronic devices are increasing. Furthermore, cost reduction is progressing, and the manufacturing process of a flexible printed wiring board (hereinafter, also referred to as FPC) is changing from the conventional batch type to a roll-to-roll type processing method.

Specifically, in the conventional FPC manufacturing process, each process such as a developing process, an etching process, and a resist peeling process is performed in a batch system. On the other hand, by performing the three processes of the developing process, the etching process, and the resist stripping process continuously in a roll-to-roll system, both high productivity and personnel reduction can be realized, and cost reduction can be realized.
While the batch-type FPC manufacturing process has an advantage that fine conditions can be set in each process, it takes time and effort. In roll-to-roll type, while cost reduction can be expected, if the processing time of one process becomes long, the processing time of the whole of the continuously following process naturally becomes long, etc. The thermal burden on the flexible metal-clad laminate also increases. In addition, it is necessary to apply a certain level of tension to the substrate to avoid wrinkles during conveyance of the substrate of the flexible metal-clad laminate, so that the roll-to-roll system is a more machine-friendly machine than the batch system. In some cases, there is a case where the mechanical load is increased, and a new problem that did not become a problem in the batch-type FPC manufacturing process, that is, a problem that a crack occurs in the polyimide film of the substrate in the roll-to-roll FPC manufacturing process Occurs.

  Conventionally, reports have been made on polyimides (for example, Patent Documents 1 and 2) in which the resistance to an alkaline solution used in the development, etching treatment, and resist stripping steps is controlled. However, even if these materials do not pose a problem in the conventional FPC manufacturing process, they are insufficient to withstand the process of continuously manufacturing the FPC by the roll-to-roll method as described above, and such a process Polyimide materials have not been provided so far that cracks do not occur even after passing through.

Unexamined-Japanese-Patent No. 06-120659 gazette JP, 2012-186377, A

  In the present invention, in view of the above, the object of the present invention is to provide a metal foil on a polyimide film to form a flexible metal-clad laminate and to manufacture a flexible printed wiring board continuously by roll-to-roll method. It is an object of the present invention to provide a polyimide film capable of suppressing a crack. Another object of the present invention is to provide a flexible metal-clad laminate in which cracks can be suppressed in the process of continuously manufacturing a flexible printed wiring board in a roll-to-roll system.

The inventors of the present invention can solve the above problems by the following novel polyimide film, flexible metal-clad laminate, and method of manufacturing a flexible circuit board.
1) A continuously produced long polyimide film having at least one polyimide resin layer, which is subjected to the following shaking test at three points on both ends and the central part of the film, and time taken for generation of a crack A polyimide film characterized by ST ≧ 900 seconds or more when ST (seconds) is measured.
<Shaking test>
A 6.0 cm × 5.5 cm square polyimide film is cut out, and a copper foil having a thickness of 12 μm is laminated on both sides thereof to obtain a copper clad laminate having copper foils on both sides, and copper of the obtained copper clad laminate After etching a part of the layer in a grid, put it in a container containing 4% aqueous sodium hydroxide solution kept at 23 ± 2 ° C and shake it at a shaking speed of 230 rpm for the time to crack (seconds Measure).
2) The polyimide film according to 1), wherein the polyimide film has a thermoplastic polyimide resin layer and a non-thermoplastic polyimide resin layer.
3) The polyimide film according to 2), wherein the polyimide film has a thermoplastic polyimide resin layer on both sides of the non-thermoplastic polyimide resin layer.
4) The said polyimide film is 25 cm or more in width, The polyimide film of any one of 1)-3) characterized by the above-mentioned.
5) The polyimide film according to any one of 1) to 4), wherein the length of the polyimide film in the longitudinal direction is 200 m or more.
6) A continuously produced long flexible metal-clad laminate having a polyimide film having at least one polyimide resin layer and a metal foil, which comprises three points at both ends and a central portion of the flexible metal-clad laminate The flexible metal-clad laminate in which ST 900 900 seconds or more when the following shaking test is performed to measure the time ST (seconds) until a crack occurs.
<Shaking test>
A 6.0 cm x 5.5 cm square flexible metal-clad laminate was cut out, a part of the metal foil was etched in a grid, and then a 4% aqueous sodium hydroxide solution kept at 23 ± 2 ° C was added. Place in a container and shake at a shaking speed of 230 rpm to measure the time (seconds) for cracking.
7) The flexible metal-clad laminate according to 6), wherein the polyimide film having at least one polyimide resin layer has a thermoplastic polyimide resin layer and a non-thermoplastic polyimide resin layer.
8) The flexible metal-clad laminate according to 7), wherein the polyimide film having at least one polyimide resin layer has a thermoplastic polyimide resin layer on both sides of a non-thermoplastic polyimide resin layer.
9) The width of the flexible metal-clad laminate is 25 cm or more, The flexible metal-clad laminate according to any one of 6) to 8).
10) The length of the longitudinal direction of the flexible metal-clad laminate is 200 m or more, The flexible metal-clad laminate according to any one of 6) to 9).
11) The flexible metal-clad laminate according to any one of 6) to 10), wherein the flexible metal-clad laminate is produced by thermally laminating a polyimide resin layer and a metal foil.
12) The flexible metal-clad laminate according to any one of 6) to 11), which is manufactured by a process including a process of casting at least one of polyimide and polyamic acid on copper foil. Metal-clad laminate.
13) A step of preparing the flexible metal-clad laminate according to any one of 6) to 12), wherein the flexible metal-clad laminate is continuously transported by roll-to-roll to form a circuit in the presence of alkali A manufacturing method of a flexible printed wiring board including a process and a process of cutting off a formed circuit board.

  The polyimide film and the flexible metal-clad laminate obtained according to the present invention can suppress the occurrence of cracks in the roll-to-roll continuous manufacturing process of the FPC.

It is a figure which shows the test piece used by the shaking test of this invention.

  The embodiments of the present invention will be described below, but the present invention is not limited thereto. In the present specification, unless otherwise specified, “A to B” representing a numerical range means “more than A (including A and greater than A) B or less (including B and less than B)”.

  The polyimide film of the present invention is a continuously produced long polyimide film having at least one polyimide resin layer, which is subjected to a shaking test at three points on both ends and the central part of the film to generate cracks. When measuring the time ST until it does, it is characterized by ST 900 900 seconds or more. Hereinafter, the continuously produced long polyimide film in the present invention will be described.

  In the process of manufacturing FPC continuously, using the wide and long flexible metal-clad laminate, the roll-to-roll process is continuously performed mainly for the developing process, the etching process and the resist stripping process. .

  In the development process, the latent image generated in the exposure process hardens and becomes insoluble in the negative type resist, and becomes soluble in the positive type in the developer, and this development dissolves the uncured and soluble parts. It becomes a process to remove. Although the developing solution differs depending on the type of resist, a sodium carbonate-based alkaline aqueous solution is generally used. The development work is carried out by spraying the liquid. The spray nozzle needs to be uniformly applied to the resist surface by swinging left and right.

  The etching step is a step of chemically dissolving the resist-free metal portion exposed in the developing step to form a conductor pattern. The metal is generally dissolved by spraying the etching solution from above and below the circuit board. Iron chloride, copper chloride and an alkali solution are mainly used as an etching solution.

  The resist removing step is a step of removing the resist on the surface on which the etching is completed and the conductor pattern is completed, so that the resist is removed to form a metal foil pattern. After the etching is completed, the peeling operation is performed after washing with water. Peeling is also performed by spray injection of a peeling solution as in the case of development and etching. The stripping solution uses an alkaline aqueous solution.

  Thus, an alkaline solution is used in at least two of the three steps of the development step, the etching step, and the resist stripping step.

  The polyimide is generally known to cause a hydrolysis reaction by contacting with an alkaline solution. In addition, tension is applied to the base in the longitudinal direction, and the spray injection of the chemical solution in each process causes the circuit board to be repeatedly stressed in the thickness direction of the circuit board.

  From these things, the cause of the occurrence of cracks in the roll-to-roll process of continuously manufacturing the FPC is the internal stress accumulated during the molding of the injection-molded product such as ABS resin (acrylonitrile butadiene styrene resin). It was hypothesized that it might be the same phenomenon as the phenomenon (chemical stress crack) which leads to stress relaxation and failure by chemical substances.

  Chemical stress cracking is a typical brittle fracture that occurs with a tensile stress equal to or less than the tensile strength of the resin (material), and a chemical adheres to or comes into contact with a location where a tensile stress occurs (a location under load) in a molded product. In the case, it is a phenomenon in which a crack occurs due to the synergistic action of a drug and stress with the passage of time. The cracked surface is smooth and exhibits a mirror-like state in the remarkable case. The generation mechanism is that a gap is created between molecules in the presence of tensile stress (under load), the drug penetrates into the gap, the intermolecular cohesive force decreases, and the molecule slips off locally. It is believed that the strain is relaxed and a crack occurs.

Based on such a hypothesis, various conditions are changed in the process of actually manufacturing the FPC continuously in a roll-to-roll system, and an experiment was conducted to find out the cause of the occurrence of cracks during this process. I found something like
(A) In the state where the circuit board is transported while being tensioned in the longitudinal direction, cracks do not occur even if water is showered.
(B) In the state where the circuit board is stopped, no cracks occur even if the chemical solution is showered.
(C) Cracking occurs when the chemical solution is showered while the circuit board is transported while being tensioned in the longitudinal direction.
(D) The place where the crack occurs is the interface between the metal foil and the film, and the crack is more likely to occur when the shape of the metal foil is closer to an acute angle than the rounded one.
(E) As the temperature of the shower ring (chemical solution) is higher, the circuit board is more likely to crack.

  From the results of (A) to (C), it was found that a crack was generated only when a chemical solution and a resin were in contact while stress (less than tensile strength) was applied to the resin called polyimide, and the hypothesis was correct all right.

  From the result of (D), when the circuit board is stressed, the ease of vibration differs depending on the difference in hardness between the place where the metal foil exists and the place where it is not, and the stress concentration at the interface between the metal foil and the film I can guess that it is easy to do. Furthermore, it has been found that, among the interface between the metal foil and the film, stress concentration is more likely to occur when the shape of the metal foil is close to an acute angle.

  From the result of (E), it can be inferred that the higher the temperature of the chemical solution, the higher the molecular mobility of the polyimide resin and the chemical solution, and the more easily the chemical solution penetrates into the polyimide resin.

  From the results of (A) to (E), the roll-to-roll type crack is more likely to occur compared to the batch type because the base material is subjected to cyclic stress in the thickness direction by tension or spray pressure, It turned out that it was because it was exposed to the chemical | medical solution.

  Accordingly, as a result of intensive investigations, the present inventors will describe in detail the environment that the material experiences when manufacturing a flexible printed wiring board continuously in a roll-to-roll method based on such consideration results. I found it to be reproduced by a simple method called shaking test.

  Explain the specific method of shaking test. A 6.0 cm × 5.5 cm square polyimide film is cut, and a copper foil having a thickness of 12 μm is laminated on both sides thereof to form a copper clad laminate having copper foils on both sides, and the copper layer of the obtained copper clad laminate A part of the sample was etched in a grid to obtain a test piece. The test piece is placed in a container containing 800 mL of a 4% aqueous solution of sodium hydroxide (23 ± 2 ° C.), and shaking time at 230 ± 2 ° C. at a shaking speed of 230 rpm is the time to crack. Measure (seconds). The shaking at this time reproduces the spray pressure on the substrate in the actual process and the repeated stress on the substrate by the spray. In addition, stress concentration is reproduced at the corner by etching a part of the copper layer in a lattice shape. The shaking test is performed three times, and the average is ST (seconds). The presence or absence of the crack was determined to be a crack when light was applied by the light box for each container containing the test piece by stopping shaking every 100 seconds and light was transmitted to the test piece. In addition, the curvature radius of the inner side of each corner | angular part of a grid | lattice form shall be 50 micrometers or less. If the curvature radius is larger than 50 μm, stress concentration is difficult and accurate evaluation can not be performed.

  In order to check whether the material will not crack even if it goes through the process of manufacturing FPC in roll-to-roll type continuously, wide and long materials are provided with metal foil in a continuous method, It is necessary to form a circuit by a manufacturing process of FPC including three steps of a roll-to-roll type developing process, an etching process and a resist peeling process using a long flexible metal-clad laminate. However, this method is not practical because it is expensive and time-consuming. The present inventors cut out a test piece from the both ends and the central part as a long film or a long flexible metal-clad laminate which is a material, and when ST in a shaking test is measured, it is 900 seconds or more. It has been found that no crack occurs if such a material is used. The shaking test can be carried out easily and at low cost, and by using a material having an ST of 900 seconds or more, it is possible to obtain a flexible metal-clad laminate which does not generate a crack very easily.

  If the ST of the polyimide film is 900 seconds or more when the shaking test is performed at both ends and the central part of the film, it is used as a flexible metal-clad laminate using this and a roll-to-roll continuous FPC manufacturing process Even when the flexible wiring board is manufactured, the occurrence of cracks is suppressed, but preferably 1200 seconds or more, and more preferably 2000 seconds or more.

  The polyimide film of the present invention is a wide and long polyimide film because it is a material used for the production of a continuous FPC as described above. The film has a ST of 900 seconds or more when a shaking test is performed at three points at both ends and the center of the film. If such a film is used, a crack does not occur in the FPC obtained even after a continuous process of the FPC, so that the FPC can be efficiently produced.

  The polyimide film of the present invention preferably has a non-thermoplastic polyimide resin layer and a thermoplastic polyimide resin layer. In the polyimide referred to herein, a polyamic acid is formed by polymerizing an aromatic diamine (hereinafter, also referred to as a diamine) and an aromatic tetracarboxylic acid dianhydride (hereinafter, also referred to as an acid dianhydride) by a conventionally known method It is obtained by imidizing this.

  Polyimides are composed of rigid structural units such as aromatic rings or aromatic complexes, so they are less entangled, and it is difficult to form a folded chain like a general polymer. On the other hand, packing of a molecular chain peculiar to the molecular chain having an imide ring occurs, and packing of the molecular chain having the local order is called aggregation structure. It has been found in the present invention that the aggregation structure of the polyimide is related to the improvement of ST. The aggregation structure can be controlled by the film forming conditions and the primary structure of the polyimide film.

  Under the polyimide production conditions, by raising the stretching or imidization temperature, it is possible to form a cohesive structure in which molecular chains are arranged in parallel and the degree of packing is high. Stretching the film in the longitudinal direction and / or width direction by 1.05 times to 1.5 times under the assumption of thermal imidization by chemical imidization using a imidization catalyst or heat treatment with a polyamic acid solution Is preferred. Biaxial stretching in which the film is stretched in any of the longitudinal direction and the width direction is more preferable because isotropy is improved. The higher the imidization temperature, the better. However, since decomposition of the polyimide partially starts at 500 ° C. or higher, it is preferable to heat at a temperature not exceeding 500 ° C. for a long time.

  In the primary structure of polyimide, molecular design is made so that packing of molecular chains can be easily formed by appropriately combining rigid structure and flexible structure. The rigid-structured monomer is, for example, para-phenylenediamine (hereinafter also referred to as PDA), but if the amount of PDA is too large, packing of the molecular chains is difficult to occur due to the rigidity of the molecular chains. On the other hand, the monomer having a bending structure is, for example, 4,4'-diaminodiphenyl ether (hereinafter also referred to as ODA), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP), oxydiphthalic acid Although it is an acid (hereinafter also referred to as ODPA), when the amount of the monomer having such flexibility is too large, packing of molecular chains becomes difficult to occur due to its flexibility. Therefore, it is possible to form an aggregate structure with a high degree of molecular chain packing by appropriately combining a rigid structure and a flexible structure.

  The diamine used for producing the non-thermoplastic polyimide film is not particularly limited. However, as described above, since the finally obtained polyimide needs to form a cohesive structure, it is preferable to use an acid dianhydride structure. It is preferred that diamines of rigid and flexible structures be used appropriately. The diamine having a rigid structure is, for example, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-3,3'- Dihydroxybiphenyl, 1,4-diaminobenzene, 1,3-diaminobenzene, 4,4'-bis (4-aminophenoxy) biphenyl and the like can be mentioned. The diamine having a flexible structure is, for example, 4,4'-diaminodiphenyl ether, 2,2-bis {4- (4-aminophenoxy) phenyl} propane, 1,3-bis (4-aminophenoxy) benzene, 1,4 -Bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene and the like.

  The acid dianhydride used for producing the non-thermoplastic polyimide film is not particularly limited either, but since the finally obtained polyimide needs to form a cohesive structure, it has a rigid structure according to the structure of the diamine. It is preferable to appropriately use acid dianhydride having a flexible structure. Specific examples of the acid dianhydride having a rigid structure include 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride and pyromellitic acid dianhydride. As the acid dianhydride having a flexible structure, 3,3 ', 4,4'-benzophenonetetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride and the like can be mentioned.

  The polyamic acid which is a precursor of polyimide is obtained by mixing and reacting the above diamine and acid dianhydride in an organic solvent so as to be substantially equimolar. As the organic solvent to be used, any solvent can be used as long as it dissolves polyamic acid, but amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used. The solid content concentration of the polyamic acid is not particularly limited, and when it is in the range of 5 to 35% by weight, a polyamic acid having sufficient mechanical strength can be obtained when it is used as a polyimide.

  The order of addition of the raw material diamine and acid dianhydride is not particularly limited, but it is possible to control the properties of the obtained polyimide not only by the chemical structure of the raw material but also by controlling the order of addition.

  A filler may be added to the polyamic acid for the purpose of improving various properties of the film such as slidability, thermal conductivity, conductivity, corona resistance, loop stiffness and the like. Any filler may be used, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

  In addition, thermosetting resins such as epoxy resin and phenoxy resin, and thermoplastic resins such as polyether ketone and polyether ether ketone may be mixed within a range that does not impair the characteristics of the entire resin layer obtained. As a method of adding these resins, a method of adding to the above polyamic acid as long as it is soluble in a solvent can be mentioned. If the polyimide is also soluble, it may be added to the polyimide solution. As long as it is insoluble in the solvent, a method may be mentioned in which the polyamic acid is first imidized and then compounded by melt-kneading. However, it is desirable not to use a melting polyimide in the present invention, since the solder heat resistance and the heat shrinkage rate of the obtained flexible metal-clad laminate may deteriorate. Therefore, it is desirable to use a soluble resin to be mixed with the polyimide.

  Examples of the diamine and acid dianhydride used for producing the thermoplastic polyimide film include the same as those used for the non-thermoplastic polyimide film, but in order to obtain a thermoplastic polyimide, the diamine having flexibility is used. It is preferable to react with acid dianhydride. Examples of flexible diamines include 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis (4-aminophenoxyphenyl) Propane and the like.

  Examples of the acid dianhydride used for producing the thermoplastic polyimide film include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid dianhydride, 3,3 ′, 4, 4'-biphenyl tetracarboxylic dianhydride, 4,4'- oxydiphthalic dianhydride etc. are mentioned.

In order to obtain the polyimide film of the present invention, an aromatic diamine and an aromatic tetracarboxylic acid dianhydride are reacted in an organic solvent to obtain a polyamic acid solution,
ii) casting a film forming dope containing the above polyamic acid solution on a support,
iii) peeling off the gel film from the support after heating on the support;
iv) further heating to imidize the remaining amic acid and drying it;
Is preferred.

  In the following steps ii), thermal imidization and chemical imidization are roughly classified. The thermal imidization method is a method in which a polyamic acid solution is cast as a film forming dope on a support without using a dehydrating ring-closing agent or the like, and the imidization is promoted only by heating. One of the chemical imidization methods is a method of promoting imidization by using, as a film-forming dope, one obtained by adding at least one of a dehydrating ring-closing agent and a catalyst as an imidization promoter to a polyamic acid solution. Either method may be used, but the chemical imidation method is more excellent in productivity.

  As a dehydrating ring-closing agent, an acid anhydride represented by acetic anhydride can be suitably used. As the catalyst, tertiary amines such as aliphatic tertiary amines, aromatic tertiary amines and heterocyclic tertiary amines can be suitably used.

  As a support which casts film forming dope, a glass plate, aluminum foil, an endless stainless steel belt, a stainless steel drum etc. may be used suitably. The heating conditions are set according to the thickness of the film finally obtained and the production rate, and after either partial imidization or drying is performed, the support is peeled off to form a polyamic acid film (hereinafter, gel film) Get).

  The end of the gel film is fixed and dried to avoid shrinkage upon curing, water, residual solvent, imidization accelerator are removed from the gel film, and the remaining amic acid is completely imidized, A film containing a polyimide is obtained. The heating conditions may be appropriately set in accordance with the thickness of the film finally obtained and the production rate.

  In the present invention, as a method of providing a plurality of polyimide resin layers, a resin layer of multiple layers may be simultaneously formed using a co-extrusion die having a plurality of flow paths in the above step ii). After proceeding to the iv) step and temporarily recovering the non-thermoplastic polyimide film, a resin layer may be newly formed thereon by coating or the like. Since a very high temperature is required for imidization, when providing a resin layer other than polyimide, it is preferable to adopt the latter method in order to suppress thermal decomposition. In addition, when providing a thermoplastic polyimide film by coating, the precursor of a thermoplastic polyimide may be apply | coated and imidation may be performed after that, and a thermoplastic polyimide solution may be apply | coated and dried.

  Also, the thermoplastic polyimide film may be obtained by casting and cooling a polyimide solution instead of casting a polyamic acid solution on a support in the above-mentioned steps.

The flexible metal-clad laminate according to the present invention is composed of a polyimide film and a metal foil. As a means to form polyimide on metal foil,
a) A polyimide film is obtained as described above, and then a metal foil is attached by heating and pressing to obtain a flexible metal-clad laminate b) An organic solvent solution containing a polyamic acid is cast on the metal foil A means for obtaining a flexible metal-clad laminate by heating and removing a solvent and imidating to obtain a flexible metal-clad laminate c) A method of obtaining a flexible metal-clad laminate by casting a polyimide-containing melt on metal foil and cooling Be Among these, when the polyimide has a melting property, the solder heat resistance and the heat shrinkage rate of the obtained flexible metal-clad laminate may deteriorate, so it is preferable to use the means of a) or b). If the polyimide is solvent soluble, an organic solvent solution containing polyimide may be used instead of the organic solvent solution containing polyamic acid. The details of a) and b) will be described below.

  In the means a), the flexible metal-clad laminate of the present invention is obtained by thermal lamination in which a metal foil is bonded to the obtained polyimide film by heating and pressing. The means and conditions for bonding metal foils may be appropriately selected from conventionally known ones.

  In the means b), the means for casting the organic solvent solution containing the polyamic acid on the metal foil is not particularly limited, and conventionally known means such as die coater, comma coater (registered trademark), reverse coater, knife coater, etc. Can be used. As a heating means for removing the solvent and imidization, any means known in the art can be used, and examples thereof include a hot air furnace and a far infrared furnace.

Similar to the method a), the chemical imidation method can shorten the heating time and improve the productivity. However, since an acid is formed from an acid anhydride which is a dehydrating ring-closing agent in the process of imidization, oxidation may proceed depending on the type of metal foil. About addition of a dehydration ring-closing agent, it is preferable to select suitably according to the kind of metal foil, and a heating condition.
When multiple layers of polyimide resin layer are provided, or when a resin layer other than polyimide is also provided, means for repeating the above casting and heating steps multiple times or forming multiple layers of cast layers by coextrusion or continuous casting and heating at one time Can be suitably used.

  In the means b), the flexible metal-clad laminate of the present invention is obtained at the same time as the imidization is completed. When metal foil is provided on both sides of the resin layer, the metal foil may be attached to the surface of the resin layer on the opposite side by heat and pressure.

  The metal foil is not particularly limited, and any metal foil can be used. For example, copper, stainless steel, nickel, aluminum, and alloys of these metals can be suitably used. Moreover, although copper, such as rolled copper and electrolytic copper, is used abundantly in a general metal-clad laminate, it can also be preferably used in the present invention.

  Moreover, the said metal foil can select what had various characteristics, such as surface treatment and surface roughness, according to the objective. Furthermore, a rustproof layer, a heat resistant layer or an adhesive layer may be applied to the surface of the metal foil.

  It does not specifically limit about the thickness of the said metal foil, According to the use, it should just be the thickness which can exhibit sufficient function.

  It is preferable that the thickness of the whole polyimide film which concerns on this invention is 7 micrometers-60 micrometers. It is preferable that the thickness be as thin as possible because the bendability as the FPC is improved. However, if the thickness is less than 7 μm, handling during processing may be difficult. If the thickness is more than 60 μm, the bendability as an FPC may be lowered or it may be difficult to reduce the thickness.

  The polyimide film and the flexible metal-clad laminate of the present invention are particularly effective when they are continuously manufactured in a roll-to-roll system. The width of the polyimide film and the flexible metal-clad laminate at that time is preferably 25 cm or more, more preferably 100 cm or more, and particularly preferably 200 cm or more. The length in the longitudinal direction of the polyimide film and the flexible metal-clad laminate is preferably 200 m or more, more preferably 1000 m or more, and particularly preferably 2000 m or more.

  By using the flexible metal-clad laminate according to the present invention, a roll-to-roll FPC can be continuously obtained. Since the primary structure of polyimide is controlled so that ST is 900 seconds or more, a process of preparing a flexible metal-clad laminate and an actual process of forming a circuit in the presence of alkali while continuously conveying by roll-to-roll It is possible to provide a manufacturing method which does not crack even after passing through.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, how to obtain | require ST of the polyimide in a synthesis example, an Example, and a comparative example, and the evaluation method of the simulation test of the state which formed the circuit in a FPC manufacturing process are as follows.

(How to determine ST, shaking test)
The film was cut out from three points at both ends and the central part of the film to make a flexible metal-clad laminate. A flexible metal-clad laminate is cut out to a size of 6.0 cm x 5.5 cm square, and a portion of the metal foil is etched in a grid shape (grid size: 1.3 mm x 1.5 mm) as shown in Fig. 1 The test pieces were obtained. The test piece is placed in a container containing 800 mL of a 4% aqueous solution of sodium hydroxide (23 ± 2 ° C.), and shaking is performed at 23 ± 2 ° C. at a shaking speed of 230 rpm to measure the time for crack initiation. After the etching, it was confirmed by an optical microscope that the curvature radius of the inner side of each of the lattice-like corner portions was 50 μm or less, and the test piece was made to be 50 μm or less. The test piece was placed in an aqueous sodium hydroxide solution. The presence or absence of the crack was determined to be a crack when light was applied by the light box for each container containing the test piece by stopping shaking every 100 seconds and light was transmitted to the test piece.

(Simulation test in FPC manufacturing process)
A tensile force of 60 N was applied to a long flexible metal-clad laminate on which a conductor pattern had been formed in advance, and the occurrence of cracks when sprayed at 45 ° C. with a 5% aqueous sodium hydroxide solution was visually observed. Those that did not generate a crack were accepted (○), and those that were cracked even if one were rejected (×).

(Synthesis of non-thermoplastic polyimide precursor)
Synthesis Example 1
2.6.3 kg of 4,4'-diaminodiphenyl ether (hereinafter also referred to as ODA) to 166.3 kg of N, N-dimethylformamide (hereinafter also referred to as DMF) while keeping the inside of the reaction system at 20 ° C. 8.10 kg of 2-bis [4- (4-amino phenoxy) phenyl] propanes (hereinafter, also referred to as BAPP) were added and stirred under a nitrogen atmosphere. After visually confirming that the ODA and BAPP were dissolved, 3.59 kg of benzophenone tetracarboxylic acid dianhydride (hereinafter also referred to as BTDA) was added. After visually confirming that BTDA was dissolved, 3.59 kg of pyromellitic dianhydride (hereinafter, also referred to as PMDA) was added, and after confirming that it was dissolved, stirring was performed for 30 minutes. After 3.56 kg of 1,4-diaminobenzene (hereinafter, also referred to as p-PDA) was added and visually confirmed to be dissolved, 7.60 kg of PMDA was gradually added and stirring was performed for 30 minutes.
Finally, a solution of 0.8 kg of BAPP in DMF so as to have a solid concentration of 7% is prepared, and this solution is gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity is 3000 poise. When it reached, the polymerization was finished.
An imidation accelerator consisting of acetic anhydride / isoquinoline / DMF (weight ratio 2.0 / 0.6 / 2.8) is added to this polyamic acid solution at a weight ratio of 50% with respect to the polyamic acid solution, continuously The mixture was stirred by a mixer, extruded from a T-die, and cast on a stainless steel endless belt. After heating this resin film at 130 ° C. for 100 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to a tenter clip, dried and imidized at 250 ° C. for 15 seconds and 450 ° C. for 87 seconds. A polyimide film having a thickness of 9 μm was obtained.

(Composition example 2)
With the reaction system maintained at 20 ° C., 7.22 kg of ODA was added to 165.9 kg of DMF, and the mixture was stirred under a nitrogen atmosphere. After visually confirming that the ODA was dissolved, 6.36 kg of 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride (hereinafter also referred to as BPDA) were added. After confirming that BPDA was dissolved, 3.48 kg of BTDA was added and stirring was performed for 30 minutes. Subsequently, 0.87 kg of ODA was added, and after confirming that it was dissolved, 3.43 kg of PDA was added. After confirming the dissolution of PDA, 8.33 kg of PMDA was gradually added, and stirring was performed for 30 minutes.
Finally, a solution of 0.8 kg of BAPP in DMF so as to have a solid concentration of 7% is prepared, and this solution is gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity is 3000 poise. When it reached, the polymerization was finished.
An imidation accelerator consisting of acetic anhydride / isoquinoline / DMF (weight ratio 2.0 / 0.6 / 2.8) is added to this polyamic acid solution at a weight ratio of 50% with respect to the polyamic acid solution, continuously The mixture was stirred by a mixer, extruded from a T-die, and cast on a stainless steel endless belt. After heating this resin film at 130 ° C. for 100 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to a tenter clip, dried and imidized at 250 ° C. for 15 seconds and 350 ° C. for 87 seconds. A polyimide film having a thickness of 9 μm was obtained.

(Composition example 3)
An imidation accelerator comprising acetic anhydride / isoquinoline / DMF (weight ratio 2.0 / 0.6 / 2.8) was added to the polyamic acid solution polymerized in Synthesis Example 1 at a weight ratio of 50% relative to the polyamic acid solution. It was added, continuously stirred by a mixer, extruded from a T-die, and cast on a stainless steel endless belt. After heating this resin film at 130 ° C. for 100 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to a tenter clip, dried and imidized at 250 ° C. for 15 seconds and 350 ° C. for 87 seconds. A polyimide film having a thickness of 9 μm was obtained.

(Composition example 4)
An imidation accelerator comprising acetic anhydride / isoquinoline / DMF (weight ratio 2.0 / 0.6 / 2.8) was added to the polyamic acid solution polymerized in Synthesis Example 1 at a weight ratio of 50% relative to the polyamic acid solution. It was added, continuously stirred by a mixer, extruded from a T-die, and cast on a stainless steel endless belt. After heating this resin film at 90 ° C. for 100 seconds, the self-supporting gel film was peeled off from the endless belt and fixed to the tenter clip. The film was stretched 1.3 times in the longitudinal direction and width direction, and then dried and imidized at 250 ° C. × 15 seconds, 350 ° C. × 87 seconds to obtain a polyimide film with a thickness of 9 μm.

(Composition example 5)
While maintaining the reaction system at 20 ° C., 17.68 kg of BPDA was added to 170.0 kg of DMF, and the mixture was stirred under a nitrogen atmosphere. After 6.14 kg of PDA was added and it was confirmed that the PDA was dissolved, 1.66 kg of 4,4'-oxydiphthalic anhydride (hereinafter also referred to as ODPA) was added. Subsequently, 4.11 kg of BAPP was added and stirring was performed for 30 minutes.
Finally, a solution of 0.4 kg of ODPA dissolved in DMF so as to have a solid concentration of 5% is prepared, and this solution is gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity is 3000 poise. When it reached, the polymerization was finished.
An imidation accelerator consisting of acetic anhydride / isoquinoline / DMF (weight ratio 2.0 / 0.6 / 2.8) is added to this polyamic acid solution at a weight ratio of 50% with respect to the polyamic acid solution, continuously The mixture was stirred by a mixer, extruded from a T-die, and cast on a stainless steel endless belt. After heating this resin film at 130 ° C. for 100 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to a tenter clip, dried and imidized at 250 ° C. for 15 seconds and 350 ° C. for 87 seconds. A polyimide film having a thickness of 9 μm was obtained.

Synthesis Example 6
While maintaining the reaction system at 20 ° C., 5.50 kg of ODA and 2.82 kg of BAPP were added to 170.0 kg of DMF, and the mixture was stirred under a nitrogen atmosphere. After visually confirming that the ODA and BAPP were dissolved, 4.43 kg of BTDA was added. After visually confirming that BTDA was dissolved, 7.79 kg of PMDA was added to confirm dissolution, and then stirring was performed for 30 minutes. After 3.42 kg of p-PDA and 0.55 kg of ODA were added and visually confirmed to be dissolved, 7.79 kg of PMDA was gradually added and stirring was performed for 30 minutes.
Finally, a solution of 0.8 kg of BAPP in DMF so as to have a solid concentration of 7% is prepared, and this solution is gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity is 3000 poise. When it reached, the polymerization was finished.
An imidation accelerator consisting of acetic anhydride / isoquinoline / DMF (weight ratio 2.0 / 0.6 / 2.8) is added to this polyamic acid solution at a weight ratio of 50% with respect to the polyamic acid solution, continuously The mixture was stirred by a mixer, extruded from a T-die, and cast on a stainless steel endless belt. After heating this resin film at 130 ° C. for 100 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to a tenter clip, dried and imidized at 250 ° C. for 15 seconds and 350 ° C. for 87 seconds. A polyimide film having a thickness of 9 μm was obtained.

Synthesis Example 7
While maintaining the reaction system at 20 ° C., 13.38 kg of m-tolidine was added to 170.0 kg of DMF, and 11.12 kg of BPDA and 5.09 kg of PMDA were added while stirring under a nitrogen atmosphere. After stirring for 30 minutes, a solution of 0.5 kg of PMDA dissolved in DMF so as to have a solid concentration of 7% is prepared, and this solution is gradually added to the above reaction solution while paying attention to viscosity increase. The polymerization was terminated when the viscosity reached 3000 poise.
An imidation accelerator consisting of acetic anhydride / isoquinoline / DMF (weight ratio 2.0 / 0.6 / 2.8) is added to this polyamic acid solution at a weight ratio of 50% with respect to the polyamic acid solution, continuously The mixture was stirred by a mixer, extruded from a T-die, and cast on a stainless steel endless belt. After heating this resin film at 130 ° C. for 100 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to a tenter clip, dried and imidized at 250 ° C. for 15 seconds and 350 ° C. for 87 seconds. A polyimide film having a thickness of 9 μm was obtained.

(Synthesis of Thermoplastic Polyimide Precursor)
Synthesis Example 8
While maintaining the reaction system at 20 ° C., 15.04 kg of BAPP was added to 164.0 kg of DMF, and 14.2 kg of BPDA was gradually added while stirring under a nitrogen atmosphere. Subsequently, 3.96 kg of BAPP was added and stirring was performed for 30 minutes. A solution of 0.7 kg of BAPP dissolved in DMF so as to have a solid concentration of 7% was adjusted, and this solution was gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity reached 300 poise. At the point of time, the polymerization was finished.

Synthesis Example 9
While maintaining the reaction system at 20 ° C., 17.96 kg of BAPP was added to 168.9 kg of DMF, and 1.93 kg of BPDA was gradually added while stirring under a nitrogen atmosphere. After visually confirming that BPDA was dissolved, 7.87 kg of PMDA was added and stirring was performed for 30 minutes. A solution of 0.7 kg of PMDA dissolved in DMF so as to have a solid concentration of 7% was prepared, and this solution was gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity reached 300 poise. At the point of time, the polymerization was finished.

Synthesis Example 10
While maintaining the inside of the reaction system at 20 ° C., 4.87 kg of 4,4′-bis (4-aminophenoxy) biphenyl (hereinafter also referred to as BAPB) is added to 167.7 kg of DMF, and stirring is performed under a nitrogen atmosphere. 3.24 kg of BPDA was added gradually. After visually confirming that the BPDA had dissolved, 12.67 kg of BAPP was added. Subsequently, 6.88 kg of PMDA was added and stirring was performed for 30 minutes. A solution of 0.7 kg of PMDA dissolved in DMF so as to have a solid concentration of 7% was prepared, and this solution was gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity reached 300 poise. At the point of time, the polymerization was finished.

Synthesis Example 11
While maintaining the reaction system at 20 ° C., 5.26 kg of BAPB and 2.86 kg of ODA were added to 164.9 kg of DMF, and 7.70 kg of BPDA was gradually added while stirring under a nitrogen atmosphere. After visually confirming that the BPDA had dissolved, 2.63 kg of BAPB and 4.88 kg of BAPP were added. After confirming that BAPB and BAPP were dissolved, 4.15 kg of PMDA was added and stirring was performed for 30 minutes. A solution of 0.7 kg of PMDA dissolved in DMF so as to have a solid concentration of 7% was prepared, and this solution was gradually added to the above reaction solution while paying attention to viscosity increase, and the viscosity reached 300 poise. At the point of time, the polymerization was finished.

Synthesis Example 12
While maintaining the reaction system at 20 ° C., 17.14 kg of BPDA was added to 172.0 kg of DMF, and while stirring under a nitrogen atmosphere, 9,92 kg of ODA and 0.63 kg of PDA were added. After stirring for 30 minutes, a solution of 0.5 kg of PDA dissolved in DMF to a solid concentration of 5% is prepared, and this solution is gradually added to the above reaction solution while paying attention to viscosity increase. The polymerization was finished when the viscosity reached 300 poise.

Synthesis Example 13
While maintaining the reaction system at 20 ° C., 18.28 kg of BAPP was added to 172.0 kg of DMF, and 9.23 kg of PMDA was added while stirring under a nitrogen atmosphere. After stirring for 30 minutes, a solution of 0.5 kg of PDA dissolved in DMF to a solid concentration of 7% is prepared, and this solution is gradually added to the above reaction solution while paying attention to viscosity increase. The polymerization was finished when the viscosity reached 300 poise.

Example 1
The polyamic acid solution obtained in Synthesis Example 8 was coated on both sides of the polyimide film obtained in Synthesis Example 1 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm.
A 12.5 μm thick electrodeposited copper foil (3EC-M3S-HTE, made by Mitsui Metals) is placed on both sides of the obtained polyimide film, and protective films (Apical 125 NPI; made by Kaneka) are used on both sides of the electrodeposited copper foil. Thermal lamination was performed under conditions of a lamination temperature of 360 ° C., a lamination pressure of 265 N / cm (27 kgf / cm), and a lamination speed of 1.0 m / min to produce a flexible metal-clad laminate.

(Example 2)
The polyamic acid solution obtained in Synthesis Example 9 was coated on both sides of the polyimide film obtained in Synthesis Example 2 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Example 3)
The polyamic acid solution obtained in Synthesis Example 9 was applied to both sides of the polyimide film obtained in Synthesis Example 5 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Example 4)
The polyamic acid solution obtained in Synthesis Example 10 was coated on both sides of the polyimide film obtained in Synthesis Example 6 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Example 5)
The polyamic acid solution obtained in Synthesis Example 8 was coated on both sides of the polyimide film obtained in Synthesis Example 4 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Example 6)
The polyamic acid solution obtained in Synthesis Example 11 was coated on both sides of the polyimide film obtained in Synthesis Example 1 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Comparative example 1)
The polyamic acid solution obtained in Synthesis Example 8 was coated on both sides of the polyimide film obtained in Synthesis Example 3 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Comparative example 2)
The polyamic acid solution obtained in Synthesis Example 9 was coated on both sides of the polyimide film obtained in Synthesis Example 3 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Comparative example 3)
The polyamic acid solution obtained in Synthesis Example 12 was coated on both sides of the polyimide film obtained in Synthesis Example 1 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Comparative example 4)
The polyamic acid solution obtained in Synthesis Example 9 was applied to both sides of 12.5 μm thick Apical NPI (manufactured by Kaneka Co., Ltd.) so that the final thickness on one side was 2.0 μm and dried at 120 ° C. for 2 minutes . Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 14.5 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Comparative example 5)
The polyamic acid solution obtained in Synthesis Example 9 was applied to both sides of 12.5 μm thick Apical AH (manufactured by Kaneka Corporation) so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes . Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 14.5 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

(Comparative example 6)
The polyamic acid solution obtained in Synthesis Example 13 was coated on both sides of the polyimide film obtained in Synthesis Example 7 so that the final thickness on one side was 2.0 μm, and dried at 120 ° C. for 2 minutes. Subsequently, imidization was carried out by heating at 350 ° C. for 1 minute to obtain a polyimide film having a total thickness of 13 μm. A flexible metal-clad laminate was produced in the same manner as in Example 1 using the obtained polyimide film.

  Table 1 shows simulated test results of ST and FPC manufacturing processes of the example and the comparative example.

  While a crack is generated in the simulation test of the FPC manufacturing process when the ST is 700 seconds or less, no crack is generated in the simulation test of the FPC manufacturing process when the ST is 900 seconds or more. If ST is high, cracks in the step of continuously manufacturing the FPC are suppressed, and further, if a material is provided such that ST is 900 seconds or more, cracks in the step of continuously manufacturing the FPC are It shows that it can be suppressed.

1. Metal foil 2. Polyimide film

Claims (11)

A continuously produced long polyimide film having at least one polyimide resin layer,
The polyimide film has a thermoplastic polyimide resin layer and a non-thermoplastic polyimide resin layer ,
The thermoplastic polyimide resin layer is
4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-amino) With flexibility selected from phenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene and 2,2-bis (4-aminophenoxyphenyl) propane With a diamine,
Pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride and 4,4'-oxydiphthalic acid It is a reaction product with an acid anhydride selected from dianhydrides,
The non-thermoplastic polyimide resin layer is
4,4'-Diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-3,3'-dihydroxybiphenyl, 1,4-diamino A diamine having a rigid structure selected from benzene, 1,3-diaminobenzene, 4,4′-bis (4-aminophenoxy) biphenyl,
4,4'-Diaminodiphenyl ether, 2,2-bis {4- (4-aminophenoxy) phenyl} propane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) A diamine having a flexible structure selected from benzene and 1,3-bis (3-aminophenoxy) benzene;
Acid dianhydrides having a rigid structure selected from 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride and pyromellitic acid dianhydride;
A reactant with an acid dianhydride having a flexible structure selected from 3,3 ′, 4,4′-benzophenonetetracarboxylic acid dianhydride and 4,4′-oxydiphthalic acid dianhydride,
A polyimide film characterized by ST ST 900 seconds or more when the following shaking test is performed at three points at both ends and the center of the film to measure a time ST until a crack is generated.
<Shaking test>
A 6.0 cm × 5.5 cm square polyimide film is cut out, and a copper foil having a thickness of 12 μm is laminated on both sides thereof to obtain a copper clad laminate having copper foils on both sides, and copper of the obtained copper clad laminate After etching a part of the layer in a grid, put it in a container containing 4% aqueous sodium hydroxide solution kept at 23 ± 2 ° C and shake it at a shaking speed of 230 rpm for the time to crack (seconds Measure). The said polyimide film has a thermoplastic polyimide resin layer on both surfaces of a non-thermoplastic polyimide resin layer, The polyimide film of Claim 1 characterized by the above-mentioned. The said polyimide film is 25 cm or more in width, The polyimide film of Claim 1 or 2 characterized by the above-mentioned. The polyimide film according to any one of claims 1 to 3 , wherein a length in a longitudinal direction of the polyimide film is 200 m or more. A continuously produced long flexible metal-clad laminate having a polyimide film having at least one polyimide resin layer and a metal foil,
The polyimide film having at least one polyimide resin layer has a thermoplastic polyimide resin layer and a non-thermoplastic polyimide resin layer,
The thermoplastic polyimide resin layer is
4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-amino) With flexibility selected from phenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene and 2,2-bis (4-aminophenoxyphenyl) propane With a diamine,
Pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride and 4,4'-oxydiphthalic acid It is a reaction product with an acid anhydride selected from dianhydrides,
The non-thermoplastic polyimide resin layer is
4,4'-Diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-3,3'-dihydroxybiphenyl, 1,4-diamino A diamine having a rigid structure selected from benzene, 1,3-diaminobenzene, 4,4′-bis (4-aminophenoxy) biphenyl,
4,4'-Diaminodiphenyl ether, 2,2-bis {4- (4-aminophenoxy) phenyl} propane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) A diamine having a flexible structure selected from benzene and 1,3-bis (3-aminophenoxy) benzene;
Acid dianhydrides having a rigid structure selected from 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride and pyromellitic acid dianhydride;
A reactant with an acid dianhydride having a flexible structure selected from 3,3 ′, 4,4′-benzophenonetetracarboxylic acid dianhydride and 4,4′-oxydiphthalic acid dianhydride,
A flexible metal-clad laminate in which ST ≧ 900 seconds or more when the following shaking test is performed on the three points of the both ends and the central part of the flexible metal-clad laminate to measure the time ST until a crack occurs.
<Shaking test>
A 6.0 cm x 5.5 cm square flexible metal-clad laminate was cut out, a part of the metal foil was etched in a grid, and then a 4% aqueous sodium hydroxide solution kept at 23 ± 2 ° C was added. Place in a container and shake at a shaking speed of 230 rpm to measure the time (seconds) for cracking. The flexible metal-clad laminate according to claim 5, wherein the polyimide film having at least one polyimide resin layer has a thermoplastic polyimide resin layer on both sides of the non-thermoplastic polyimide resin layer. The width of the flexible metal-clad laminate is 25 cm or more, The flexible metal-clad laminate according to claim 5 or 6 . The length in the longitudinal direction of the flexible metal-clad laminate is 200 m or more, The flexible metal-clad laminate according to any one of claims 5 to 7 . The flexible metal-clad laminate according to any one of claims 5 to 8 , wherein the flexible metal-clad laminate is produced by thermally laminating a polyimide resin layer and a metal foil. The flexible metal-clad laminate according to any one of claims 5 to 9 , wherein the flexible metal-clad laminate is manufactured by a process including a process of casting at least one of polyimide and polyamic acid on copper foil. Laminated board. A process of preparing a flexible metal-clad laminate according to any one of claims 5 to 10 , a process of forming a circuit in the presence of alkali while continuously conveying the flexible metal-clad laminate by roll-to-roll, The manufacturing method of a flexible printed wiring board including the process of cutting off the formed circuit board.