JP2005199481A - Adhesive film and flexible metal clad laminated sheet enhanced in dimensional stability obtained therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive film for use in obtaining a flexible metal clad laminated sheet suppressed in the coccurrence of a dimensional change when manufactured by a lamination method, and the flexible metal clad laminated sheet obtained by laminating a metal foil to the adhesive film. <P>SOLUTION: The adhesive film is constituted by providing an adhesive layer containing a thermoplastic polyimide at least on one side of an insulating film and the flexible metal clad laminated sheet is obtained by laminating the metal foil to the adhesive film. The adhesive film is characterized in that the tensile elastic modulus in the MD direction of the insulating film is 6.5-12 GPa, the coefficient of thermal expansion thereof at 50-200°C is 3-20 ppm/°C and the tensile elastic modulus in the MD direction of the adhesive film is 5.5-11 GPa. The flexible metal clad laminated sheet obtained from the adhesive film is also disclosed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an adhesive film in which an adhesive layer containing a thermoplastic polyimide is provided on at least one surface of an insulating film, and a flexible metal-clad laminate obtained by bonding a metal foil to the adhesive film using a hot roll laminator. More specifically, the insulating film has a tensile elastic modulus in the MD direction of 6.5 to 12 GPa, and a thermal expansion coefficient at 50 to 200 ° C. of 3 to 20 ppm / ° C. A flexible metal-clad laminate obtained by laminating a metal foil to a film by a hot roll laminator, preferably with a dimensional change rate before and after removing the metal foil, and heating at 250 ° C. for 30 minutes after removing the metal foil Flexible metal-clad laminate in which the total dimensional change rate before and after is in the range of -0.08 to + 0.08% in both the longitudinal direction (hereinafter also referred to as MD direction) and the width direction (hereinafter also referred to as TD direction) It is related with a board and its manufacturing method.

  In recent years, the demand for various printed circuit boards has increased along with the reduction in weight, size and density of electronic products. In particular, the demand for flexible laminates (also referred to as flexible printed circuit boards (FPCs), etc.) has increased. ing. The flexible laminate has a structure in which a circuit made of a metal foil is formed on an insulating film.

  The flexible laminate is generally formed of various insulating materials, and a flexible insulating film is used as a substrate, and a metal foil is bonded to the surface of the substrate by heating and pressure bonding via various adhesive materials. Manufactured by. A polyimide film or the like is preferably used as the insulating film. As the adhesive material, a thermosetting adhesive such as epoxy or acrylic is generally used (FPC using these thermosetting adhesives is hereinafter also referred to as three-layer FPC).

  Thermosetting adhesives have the advantage that they can be bonded at relatively low temperatures. However, in the future, as required characteristics such as heat resistance, flexibility, and electrical reliability become stricter, it is considered that it is difficult to cope with a three-layer FPC using a thermosetting adhesive. On the other hand, an FPC (hereinafter also referred to as a two-layer FPC) in which a metal layer is directly provided on an insulating film or a thermoplastic polyimide is used for an adhesive layer has been proposed. This two-layer FPC has characteristics superior to those of the three-layer FPC, and demand is expected to increase in the future.

  As a method for producing a flexible metal-clad laminate for use in a two-layer FPC, a polyamic acid, which is a polyimide precursor, is cast on a metal foil, applied, and then casted directly onto a polyimide film by sputtering or plating. Examples thereof include a metallizing method for providing a metal layer and a laminating method for bonding a polyimide film and a metal foil through a thermoplastic polyimide. Among these, the lamination method is superior in that the thickness range of the metal foil that can be handled is wider than that of the casting method and the apparatus cost is lower than that of the metalizing method. As a device for laminating, a hot roll laminating device or a double belt press device for continuously laminating a roll-shaped material is used. Of these, the hot roll laminating method can be used more preferably from the viewpoint of productivity.

  When a conventional three-layer FPC was produced by a laminating method, a thermosetting resin was used for the adhesive layer, so that the laminating temperature could be less than 200 ° C. (see Patent Document 1). On the other hand, since the two-layer FPC uses thermoplastic polyimide as an adhesive layer, it is necessary to apply a high temperature of 200 ° C. or higher, and in some cases, close to 400 ° C., in order to develop heat-fusibility. Therefore, residual distortion occurs in the flexible metal-clad laminate obtained by laminating, and it appears as a dimensional change when wiring is formed by etching and when solder reflow is performed to mount components.

  In particular, in the laminating method, when an adhesive layer containing a thermoplastic polyimide is provided on a polyimide film, the polyamic acid which is a precursor of the thermoplastic polyimide is cast and applied, and then continuously heated to imidize, Since the heating and pressurization is continuously performed when the metal foil is bonded, the material is often placed in a heating environment under tension. Therefore, different thermal stresses are generated in the MD direction and the TD direction. Specifically, a pulling force acts in the MD direction where tension is applied, and conversely, a shrinking force acts in the TD direction. As a result, when the metal foil is etched from the flexible laminate and when heated through solder reflow, this strain is released, the MD direction contracts, and conversely, the TD direction expands.

  In recent years, in order to achieve miniaturization and weight reduction of electronic devices, wiring provided on a substrate has been miniaturized, and components to be mounted are mounted with miniaturization and high density. For this reason, if the dimensional change after forming the fine wiring is increased, there is a problem that the component and the board are not well connected due to deviation from the component mounting position in the design stage.

Therefore, attempts have been made to suppress dimensional changes by controlling the laminating pressure or controlling the tension of the adhesive film (see Patent Document 2 or 3). However, although the dimensional change is improved by these means, it is not sufficient yet, and further improvement of the dimensional change is demanded.
JP-A-9-199830 JP 2002-326308 A JP 2002-326280 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an adhesive film from which a flexible metal-clad laminate in which the occurrence of dimensional change is suppressed when produced by a laminating method, and a metal An object of the present invention is to provide a flexible metal-clad laminate obtained by laminating foil, particularly a flexible metal-clad laminate capable of suppressing the occurrence of dimensional changes when produced by a laminating method.

  As a result of intensive studies in view of the above problems, the present inventors have reduced the generation of thermal stress during imidization and lamination of thermoplastic polyimide by controlling the tensile modulus of the core film within a specific range. The inventors have independently found that the occurrence of dimensional changes can be effectively suppressed, and have completed the present invention.

  That is, the first of the present invention is an adhesive film in which an adhesive layer containing thermoplastic polyimide is provided on at least one surface of the insulating film, and the tensile elastic modulus in the MD direction of the insulating film is 6.5 to 12 GPa. The present invention relates to an adhesive film.

  A preferred embodiment relates to the above adhesive film, wherein the insulating film has a thermal expansion coefficient of 3 to 20 ppm / ° C. at 50 to 200 ° C.

  A further preferred embodiment relates to the above-mentioned adhesive film, wherein the tensile elastic modulus in the MD direction is 5.5 to 11 GPa.

  A second aspect of the present invention relates to a flexible metal-clad laminate obtained by bonding a metal foil to the adhesive film using a hot roll laminator having a pair of metal rolls.

  In a preferred embodiment, the dimensional change rate before and after removing the metal foil, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil is −0.08 in both the MD direction and the TD direction. It is related with the said flexible metal-clad laminated board characterized by being in the range of -0.08%.

  In the flexible metal-clad laminate of the present invention, the occurrence of dimensional changes is suppressed, and in particular, the occurrence of dimensional changes in the laminating method can be effectively suppressed. Specifically, the dimensional change rate before and after removing the metal foil and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil are −0.08 in both the MD direction and the TD direction. It can be in the range of ˜ + 0.08%. Therefore, it can be suitably used for an FPC or the like in which fine wiring is formed, and problems such as misalignment can be improved.

  Embodiments of the present invention will be described below.

  The adhesive film according to the present invention is characterized in that an adhesive layer containing thermoplastic polyimide is provided on at least one surface of an insulating film.

  As the insulating film used in the present invention, any film such as a polyimide film, a polyester film, a liquid crystal polymer film, a nylon film, an aramid film, and a polyamideimide film may be used, but a polyimide film from the viewpoint of heat resistance and insulating characteristics. Is preferably used.

  Hereinafter, the case where a polyimide film is used as the insulating film will be described based on an example of the embodiment.

  Any known method can be used as a method for producing the polyamic acid that is a precursor of the polyimide used in the present invention. Usually, the aromatic acid dianhydride and the aromatic diamine are substantially equimolar amounts in an organic solvent. The polyamic acid organic solvent solution obtained by dissolving therein is produced by stirring under controlled temperature conditions until the polymerization of the acid dianhydride and diamine is completed. These polyamic acid solutions are usually obtained at a concentration of 5 to 35 wt%, preferably 10 to 30 wt%. When the concentration is in this range, an appropriate molecular weight and solution viscosity are obtained.

As the polymerization method, any known method and a combination thereof can be used. The characteristic of the polymerization method in the polymerization of polyamic acid is the order of addition of the monomers, and the physical properties of the polyimide obtained can be controlled by controlling the order of addition of the monomers. Therefore, in the present invention, any method of adding monomers may be used for the polymerization of polyamic acid. The following method is mentioned as a typical polymerization method. That is,
1) A method in which an aromatic diamine is dissolved in an organic polar solvent and this is reacted with a substantially equimolar amount of an aromatic tetracarboxylic dianhydride for polymerization.
2) An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Then, the method of superposing | polymerizing using an aromatic diamine compound so that an aromatic tetracarboxylic dianhydride and an aromatic diamine compound may become substantially equimolar in all the processes.
3) An aromatic tetracarboxylic dianhydride and an excess molar amount of the aromatic diamine compound are reacted in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after adding an aromatic diamine compound here, using the aromatic tetracarboxylic dianhydride so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps. How to polymerize.
4) A method in which an aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent and then polymerized using an aromatic diamine compound so as to be substantially equimolar.
5) A method of polymerizing by reacting a substantially equimolar mixture of aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent.
And so on. These methods may be used singly or in combination.

  In the present invention, the polyamic acid obtained by using any of the above polymerization methods may be used, and the polymerization method is not particularly limited.

  In order to obtain a polyimide film having physical properties suitable for use in the adhesive film according to the present invention, a polymerization method for obtaining a prepolymer using a diamine component having a rigid structure typified by paraphenylenediamine or substituted benzidine is used. It is preferable to use it. By using this method, a polyimide film having a high elastic modulus and a small hygroscopic expansion coefficient tends to be easily obtained. In this method, the molar ratio of the diamine having a rigid structure used in preparing the prepolymer to the acid dianhydride is 100: 70 to 100: 99 or 70: 100 to 99: 100, and further 100: 75 to 100: 90 or 75: 100-90: 100 is preferable. If this ratio is less than the above range, it is difficult to obtain the effect of improving the elastic modulus and hygroscopic expansion coefficient, and if it exceeds the above range, adverse effects such as excessively low thermal expansion coefficient and reduced tensile elongation may occur.

  Here, the material used for the polyamic acid composition concerning this invention is demonstrated.

  Suitable acid anhydrides that can be used in the present invention include pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid diacid. Anhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic Acid dianhydride, 4,4′-oxyphthalic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride Bis (3,4-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane Dianhydride, bis 2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, p -Phenylene bis (trimellitic acid monoester anhydride), ethylene bis (trimellitic acid monoester anhydride), bisphenol A bis (trimellitic acid monoester anhydride) and the like, Single or a mixture of arbitrary ratios can be used preferably.

  In order to obtain a polyimide film having physical properties suitable for use in the adhesive film according to the present invention, among these acid dianhydrides, pyromellitic dianhydride and / or 3,3 ′, 4, Preference is given to using 4′-benzophenone tetracarboxylic dianhydride and / or 4,4′-oxyphthalic dianhydride and / or 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  Among these acid dianhydrides, preferred amounts of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and / or 4,4′-oxyphthalic dianhydride are all acid dianhydrides. Is 60 mol% or less, preferably 55 mol% or less, more preferably 50 mol% or less. If the amount of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and / or 4,4′-oxyphthalic dianhydride exceeds this range, the glass transition temperature of the polyimide film becomes too low. In addition, the storage elastic modulus at the time of heating becomes too low, and film formation itself may become difficult, which is not preferable.

  Moreover, when using pyromellitic dianhydride, the preferable usage-amount is 40-100 mol%, More preferably, it is 45-100 mol%, Most preferably, it is 50-100 mol%. By using pyromellitic dianhydride in this range, the glass transition temperature and the storage elastic modulus at the time of heating can be easily maintained in a range suitable for use or film formation.

  Suitable diamines that can be used in the polyimide precursor polyamic acid composition according to the present invention include 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenylmethane, benzidine, 3,3′-dichlorobenzidine, 3, 3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenylsulfone, 4, 4'-diaminodiphenyl sulfone, 4,4'-oxydianiline, 3,3'-oxydianiline, 3,4'-oxydianiline, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyldiethylsilane 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenyl Tylphosphine oxide, 4,4′-diaminodiphenyl N-methylamine, 4,4′-diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene, 1, 2-diaminobenzene, bis {4- (4-aminophenoxy) phenyl} sulfone, bis {4- (3-aminophenoxy) phenyl} sulfone, 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, 3,3′-diaminobenzophenone, 4,4′-diamy Benzophenone and their analogs thereof.

  If these diamines are classified into so-called rigid diamines such as diaminobenzenes and benzidines and diamines having flexible structures such as ether groups, sulfone groups, ketone groups and sulfide groups, rigid structures and flexible diamines are considered. The use ratio of the structural diamine is 80/20 to 20/80, preferably 70/30 to 30/70, particularly preferably 60/40 to 30/70, in molar ratio. If the use ratio of the rigid diamine exceeds the above range, the tensile elongation of the resulting film tends to be small, and if it falls below this range, the glass transition temperature becomes too low or the storage modulus during heat decreases. This is not preferable because it may cause adverse effects such as difficulty in film formation.

  The polyimide film used in the present invention is obtained by appropriately determining the type and blending ratio of the aromatic dianhydride and aromatic diamine so as to be a film having desired characteristics within the above range. Can do.

  As the preferred solvent for synthesizing the polyamic acid, any solvent can be used as long as it dissolves the polyamic acid. However, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N- Examples thereof include methyl-2-pyrrolidone, and N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.

  In addition, a filler can be added for the purpose of improving various film properties such as slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness. 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.

The particle size of the filler is not particularly limited because it is determined by the film characteristics to be modified and the kind of filler to be added, but generally the average particle size is 0.05 to 100 μm, preferably 0.1. It is -75 micrometers, More preferably, it is 0.1-50 micrometers, Most preferably, it is 0.1-25 micrometers. If the particle size is below this range, the modification effect is less likely to appear. If the particle size is above this range, the surface properties may be greatly impaired or the mechanical properties may be greatly deteriorated. Further, the number of added parts of the filler is not particularly limited because it is determined by the film properties to be modified, the filler particle diameter, and the like. Generally, the addition amount of the filler is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight with respect to 100 parts by weight of the polyimide. If the amount of filler added is less than this range, the effect of modification by the filler hardly appears, and if it exceeds this range, the mechanical properties of the film may be greatly impaired. Addition of filler
1. 1. A method of adding to a polymerization reaction solution before or during polymerization 2. A method of kneading fillers using three rolls after the completion of polymerization. Any method such as preparing a dispersion containing filler and mixing it with a polyamic acid organic solvent solution may be used, but a method of mixing a dispersion containing filler with a polyamic acid solution, particularly immediately before film formation. This method is preferable because the contamination by the filler in the production line is minimized. When preparing a dispersion containing a filler, it is preferable to use the same solvent as the polymerization solvent for the polyamic acid. Further, in order to disperse the filler satisfactorily and stabilize the dispersion state, a dispersant, a thickener and the like can be used within a range not affecting the film physical properties.

  A conventionally well-known method can be used about the method of manufacturing a polyimide film from these polyamic acid solutions. This method includes a thermal imidization method and a chemical imidization method, and either method may be used to produce a film, but the imidization by the chemical imidation method is more preferably used in the present invention. It tends to be easy to obtain a polyimide film for semiconductor mounting having various characteristics.

In addition, the production process of the polyimide film particularly preferable in the present invention is as follows.
a) a step of reacting an aromatic diamine and an aromatic tetracarboxylic dianhydride in an organic solvent to obtain a polyamic acid solution;
b) casting a film-forming dope containing the polyamic acid solution on a support;
c) a step of peeling the gel film from the support after heating on the support;
d) further heating to imidize and dry the remaining amic acid,
It is preferable to contain.

  In the above step, a curing agent containing a dehydrating agent typified by an acid anhydride such as acetic anhydride and an imidation catalyst typified by a tertiary amine such as isoquinoline, β-picoline or pyridine may be used. .

  In the following, a preferred embodiment of the present invention, a method of chemical curing, will be described as an example to describe the process for producing a polyimide film. However, the present invention is not limited to the following examples. The film forming conditions and heating conditions can vary depending on the type of polyamic acid, the thickness of the film, and the like.

  A film forming dope is obtained by mixing a dehydrating agent and an imidization catalyst in a polyamic acid solution at a low temperature. Subsequently, this film-forming dope is cast into a film on a support such as a glass plate, an aluminum foil, an endless stainless steel belt, or a stainless drum, and the temperature on the support is 80 ° C. to 200 ° C., preferably 100 ° C. to 180 ° C. By heating in the region, the dehydrating agent and imidization catalyst are activated to partially cure and / or dry, and then peel from the support to obtain a polyamic acid film (hereinafter referred to as gel film).

The gel film is in the intermediate stage of curing from polyamic acid to polyimide, has self-supporting properties, and has the formula (1)
(AB) × 100 / B (1)
In formula (1), A and B represent the following.
A: Weight of gel film B: The volatile content calculated from the weight after heating the gel film at 450 ° C. for 20 minutes is in the range of 5 to 500% by weight, preferably 5 to 200% by weight, more preferably 5 to 5%. It is in the range of 150% by weight. It is preferable to use a film in this range, and problems such as film breakage, uneven film color due to drying unevenness, and characteristic variations may occur during the baking process.

  The preferable amount of the dehydrating agent is 0.5 to 5 mol, preferably 1.0 to 4 mol, relative to 1 mol of the amic acid unit in the polyamic acid. Moreover, the preferable quantity of an imidation catalyst is 0.05-3 mol with respect to 1 mol of amic acid units in a polyamic acid, Preferably it is 0.2-2 mol.

  If the dehydrating agent and the imidization catalyst are below the above ranges, chemical imidization may be insufficient, and may break during firing or mechanical strength may decrease. Moreover, when these amounts exceed the above range, the progress of imidization becomes too fast, and it may be difficult to cast into a film, which is not preferable.

  The end of the gel film is fixed to avoid shrinkage during curing, water, residual solvent, residual conversion agent and catalyst are removed, and the remaining amic acid is completely imidized to obtain the present invention. A polyimide film is obtained. At this time, it is preferable to finally heat at a temperature of 400 to 650 ° C. for 5 to 400 seconds. Above this temperature and / or for a long time, the film may suffer from thermal degradation and may cause problems. Conversely, if the temperature is lower than this temperature and / or the time is shorter, the predetermined effect may not be exhibited.

  Moreover, in order to relieve the internal stress remaining in the film, heat treatment can be performed under the minimum tension necessary for transporting the film. This heat treatment may be performed in the film manufacturing process, or may be provided separately. The heating conditions vary depending on the characteristics of the film and the apparatus used, and therefore cannot be determined in general. The internal stress can be relaxed by heat treatment at a temperature of 450 ° C. or lower for 1 to 300 seconds, preferably 2 to 250 seconds, particularly preferably 5 to 200 seconds.

As mentioned above, adhesive film suitable for use in hot roll laminating by controlling the various characteristics of the polyimide film as follows depending on the type of monomer, the order of addition of monomers during polymerization, the imidization method selected, etc. A flexible metal-clad laminate having excellent dimensional stability can be obtained by laminating with a metal foil.
1. The tensile modulus in the MD direction is 6.5 to 12 GPa, preferably 7 to 11 GPa
The coefficient of thermal expansion at 2.50 to 200 ° C. is 3 to 20 ppm / ° C., preferably 5 to 18 ppm / ° C., particularly preferably 8 to 16 ppm / ° C.
When the tensile elastic modulus in the MD direction of the polyimide film is lower than the above range, it is easily affected by the tension at the time of imidization or thermal lamination of the thermoplastic polyimide contained in the adhesive layer, so that the MD direction differs from the TD direction. Thermal stress is generated, and the dimensional change of the obtained flexible metal-clad laminate may increase. Conversely, if the tensile modulus exceeds the above range, the flexibility of the resulting flexible metal-clad laminate may be inferior.

  When the thermal expansion coefficient of the polyimide film exceeds the above range, the thermal expansion coefficient when the adhesive film is provided as an adhesive film is too larger than the metal foil, so the thermal behavior of the adhesive film and the metal foil during thermal lamination In some cases, the difference increases and the dimensional change of the resulting flexible metal-clad laminate increases. If the thermal expansion coefficient is below the above range, the adhesive film has a thermal expansion coefficient that is too small compared to the metal foil, so the difference in thermal behavior during thermal lamination is still large, and the dimensions of the resulting flexible metal-clad laminate Changes can be significant.

  In the present invention, a commercially available polyimide film may be used as long as the film characteristics are within the above ranges. Examples of commercially available polyimide films include Apical (manufactured by Kaneka Chemical Co., Ltd.), Kapton (manufactured by DuPont), and Upilex (manufactured by Ube Industries).

  As the thermoplastic polyimide contained in the adhesive layer, thermoplastic polyimide, thermoplastic polyamideimide, thermoplastic polyetherimide, thermoplastic polyesterimide and the like can be suitably used. Among these, thermoplastic polyesterimide is particularly preferably used from the viewpoint of low moisture absorption characteristics.

  In view of the fact that lamination with an existing apparatus is possible and the heat resistance of the resulting metal-clad laminate is not impaired, the thermoplastic polyimide in the present invention has a glass transition temperature (150 to 300 ° C.). Tg) is preferred. In addition, Tg can be calculated | required from the value of the inflexion point of the storage elastic modulus measured with the dynamic viscoelasticity measuring apparatus (DMA).

  The polyamic acid that is a precursor of the thermoplastic polyimide is not particularly limited, and any known polyamic acid can be used. Also for the production, known raw materials, reaction conditions, and the like can be used (for example, see Examples described later). Moreover, you may add an inorganic or organic filler as needed.

  The adhesive film used for manufacturing the flexible metal-clad laminate according to the present invention can be obtained by providing an adhesive layer containing thermoplastic polyimide on at least one surface of the insulating film. Suitable examples of the method for producing the adhesive film include a method of forming an adhesive layer on the insulating film to be a base film, or a method of forming the adhesive layer into a sheet and bonding it to the base film. obtain. Among these, when taking the former method, if the polyamic acid that is the precursor of the thermoplastic polyimide contained in the adhesive layer is completely imidized, the solubility in an organic solvent may decrease, It may be difficult to provide the adhesive layer on the base film. Therefore, from the above viewpoint, it is more preferable to prepare a solution containing polyamic acid which is a precursor of thermoplastic polyimide, apply this to a base film, and then imidize. As the imidization method at this time, either a thermal cure method or a chemical cure method can be used.

  Regardless of which imidation procedure is employed, heating is performed in order to promote imidization efficiently, and the temperature at that time ranges from (glass transition temperature of thermoplastic polyimide−100 ° C.) to (glass transition temperature + 200 ° C.). It is preferable to set within the range of (Glass transition temperature of thermoplastic polyimide−50 ° C.) to (Glass transition temperature + 150 ° C.). The higher the temperature of the heat curing, the easier the imidization occurs, so the curing speed can be increased, which is preferable in terms of productivity. However, if it is too high, the thermoplastic polyimide may cause thermal decomposition. On the other hand, if the temperature of the heat curing is too low, imidization is difficult to proceed even with chemical curing, and the time required for the curing process becomes long.

  As for the imidization time, it suffices to take a sufficient time for the imidization and drying to be substantially completed, and although it is not uniquely limited, generally it is appropriately set within a range of about 1 to 600 seconds. Is done. Further, for the purpose of improving the melt fluidity of the adhesive layer, it is possible to intentionally lower the imidization rate and / or leave the solvent.

  The tension applied during imidization is preferably in the range of 1 kg / m to 15 kg / m, and particularly preferably in the range of 5 kg / m to 10 kg / m. If the tension is smaller than the above range, sagging or meandering may occur during film conveyance, which may cause problems such as wrinkling during winding or inability to uniformly wind. On the other hand, when it is larger than the above range, even if an insulating film having a high elastic modulus is used, the influence of the tension becomes strong, which may affect the dimensional change.

  The method for casting and applying the polyamic acid solution to the base film is not particularly limited, and existing methods such as a die coater, a reverse coater, and a blade coater can be used.

  In addition, the polyamic acid solution may contain other materials such as a filler, depending on the application. In addition, if necessary, various surface treatments such as corona treatment, plasma treatment, and coupling treatment may be performed on the surface of the core film before providing the adhesive layer.

  The thickness configuration of each layer of the adhesive film may be appropriately adjusted so as to have a total thickness according to the application, but the tensile elastic modulus in the MD direction of the obtained adhesive film is 5.5 to 11 GPa, preferably 6.5. -10 GPa. When the tensile modulus is below the above range, it becomes more susceptible to tension during thermal lamination, so different thermal stresses occur in the MD and TD directions, resulting in a large dimensional change in the resulting flexible metal-clad laminate There is. Conversely, if the tensile modulus exceeds the above range, the flexibility of the resulting flexible metal-clad laminate may be inferior. Generally, since the tensile elastic modulus of the adhesive layer is smaller than that of the insulating film, the tensile elastic modulus of the adhesive film tends to decrease as the thickness ratio of the adhesive layer increases.

  In addition, if the difference between the thermal expansion coefficient of the adhesive film and the thermal expansion coefficient of the metal foil to be bonded increases, the difference in expansion / contraction behavior at the time of bonding increases, so that the resulting flexible metal-clad laminate is distorted. It may remain, and the rate of dimensional change after removal of the metal foil may increase. The thermal expansion coefficient of the adhesive film is preferably adjusted so that the value at 200 to 300 ° C. is in the range of the thermal expansion coefficient ± 6 ppm / ° C. of the metal foil. The thermal expansion coefficient of the adhesive film can be adjusted by changing the thickness ratio between the insulating film layer and the adhesive layer.

  The flexible metal-clad laminate according to the present invention can be obtained by bonding a metal foil to the adhesive film. The metal foil to be used is not particularly limited, but when the flexible metal-clad laminate of the present invention is used for electronic equipment / electric equipment, for example, copper or copper alloy, stainless steel or its alloy, nickel Alternatively, a foil made of a nickel alloy (including 42 alloy), aluminum, or an aluminum alloy can be used. In general flexible metal-clad laminates, copper foil such as rolled copper foil and electrolytic copper foil is frequently used, but it can also be preferably used in the present invention. In addition, the antirust layer, the heat-resistant layer, or the contact bonding layer may be apply | coated to the surface of these metal foil.

  In the present invention, the thickness of the metal foil is not particularly limited, and may be any thickness as long as a sufficient function can be exhibited depending on the application. As a method for bonding the adhesive film and the metal foil, for example, a heat roll laminating apparatus having a pair of metal rolls or a continuous process using a double belt press (DBP) can be used. Among these, it is preferable to use a hot roll laminating apparatus having a pair of metal rolls because the apparatus configuration is simple and advantageous in terms of maintenance cost. The “heat roll laminating apparatus having a pair of metal rolls” herein may be an apparatus having a metal roll for heating and pressurizing a material, and the specific apparatus configuration is particularly limited. It is not a thing.

  The specific configuration of the means for carrying out the thermal lamination is not particularly limited, but a protective material is disposed between the pressing surface and the metal foil in order to improve the appearance of the resulting laminate. It is preferable to do. The protective material is not particularly limited as long as it can withstand the heating temperature in the heat laminating process, and preferably a heat-resistant plastic such as a non-thermoplastic polyimide film, a metal foil such as a copper foil, an aluminum foil, or a SUS foil. Can be used. Among these, a non-thermoplastic polyimide film is more preferably used from the viewpoint of excellent balance between heat resistance and reusability. In addition, if the thickness is thin, the function of buffering and protecting at the time of lamination will not be sufficiently fulfilled, so the thickness of the non-thermoplastic polyimide film is preferably 75 μm or more.

  Further, the protective material does not necessarily have to be a single layer, and may have a multilayer structure of two or more layers having different characteristics.

  The heating method of the material to be laminated in the heat laminating means is not particularly limited. For example, heating using a conventionally known method capable of heating at a predetermined temperature, such as a heat circulation method, a hot air heating method, an induction heating method, or the like. Means can be used. Similarly, the pressurization method of the material to be laminated in the heat laminating means is not particularly limited, and a conventionally known method capable of applying a predetermined pressure such as a hydraulic method, a pneumatic method, a gap pressure method, etc. The pressurizing means adopting can be used.

  The heating temperature in the thermal laminating step, that is, the laminating temperature, is preferably a glass transition temperature (Tg) of the adhesive film + 50 ° C. or higher, and more preferably Tg + 100 ° C. or higher of the adhesive film. If it is Tg + 50 degreeC or more temperature, an adhesive film and metal foil can be heat-laminated favorably. Moreover, if it is Tg + 100 degreeC or more, the lamination speed | rate can be raised and the productivity can be improved more.

  The laminating speed in the thermal laminating step is preferably 0.5 m / min or more, and more preferably 1.0 m / min or more. If it is 0.5 m / min or more, sufficient thermal lamination is possible, and if it is 1.0 m / min or more, productivity can be further improved.

  The higher the pressure in the heat laminating step, that is, the laminating pressure, is advantageous in that the laminating temperature can be lowered and the laminating speed can be increased. There is a tendency to get worse. On the other hand, if the lamination pressure is too low, the adhesive strength of the metal foil of the laminate obtained is lowered. Therefore, the lamination pressure is preferably in the range of 49 to 490 N / cm (5 to 50 kgf / cm), and more preferably in the range of 98 to 294 N / cm (10 to 30 kgf / cm). Within this range, the three conditions of the lamination temperature, the lamination speed and the lamination pressure can be made favorable, and the productivity can be further improved.

  The adhesive film tension in the laminating step is preferably 0.01 to 4 N / cm, more preferably 0.02 to 2.5 N / cm, and particularly preferably 0.05 to 1.5 N / cm. When the tension is below the above range, sagging or meandering occurs during the conveyance of the laminate, and it is difficult to obtain a flexible metal-clad laminate having a good appearance because it is not uniformly fed to the heating roll. On the other hand, if it exceeds the above range, the influence of the tension becomes so strong that it cannot be relaxed by controlling the Tg and storage elastic modulus of the adhesive layer, and the dimensional stability may be inferior.

  In order to obtain the flexible metal-clad laminate according to the present invention, it is preferable to use a thermal laminating apparatus that continuously press-bonds the material to be laminated while heating, but in this thermal laminating apparatus, before the thermal laminating means, A laminated material feeding means for feeding the laminated material may be provided, or a laminated material winding means for winding the laminated material may be provided after the thermal laminating means. By providing these means, the productivity of the thermal laminating apparatus can be further improved. The specific configuration of the laminated material feeding means and the laminated material winding means is not particularly limited, and for example, an adhesive film, a metal foil, or a known roll shape capable of winding up the obtained laminated plate A winder etc. can be mentioned.

  Furthermore, it is more preferable to provide a protective material winding means and a protective material feeding means for winding and feeding the protective material. If these protective material take-up means and protective material feeding means are provided, the protective material can be reused by winding the protective material once used in the thermal laminating step and installing it again on the pay-out side. . Further, when winding up the protective material, end position detecting means and winding position correcting means may be provided in order to align both ends of the protective material. As a result, the end portions of the protective material can be aligned and wound with high accuracy, so that the efficiency of reuse can be increased. The specific configurations of the protective material winding means, the protective material feeding means, the end position detecting means, and the winding position correcting means are not particularly limited, and various conventionally known devices can be used.

  In the flexible metal-clad laminate obtained by the manufacturing method according to the present invention, the dimensional change rate before and after removing the metal foil, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil. However, it is very preferable that both the MD direction and the TD direction are in the range of -0.08 to + 0.08%. The rate of dimensional change before and after removal of the metal foil is expressed as a ratio between a difference between a predetermined dimension in the flexible metal-clad laminate before the etching process and a predetermined dimension after the etching process and a predetermined dimension before the etching process. . The dimensional change rate before and after heating is represented by a ratio between a difference between a predetermined dimension in the flexible metal-clad laminate after the etching process and a predetermined dimension after the heating process and a predetermined dimension before the heating process.

  If the dimensional change rate is out of this range, the dimensional change at the time of component mounting becomes large after forming fine wiring in the flexible metal-clad laminate, and it will deviate from the component mounting position at the design stage. Become. As a result, there is a possibility that the component to be mounted and the board are not connected well. In other words, if the rate of dimensional change is within the above range, it can be considered that there is no problem in component mounting.

  The method for measuring the dimensional change rate is not particularly limited, and any method known in the art can be used as long as it can measure the increase or decrease in dimensions that occurs before and after the etching or heating process in the flexible metal-clad laminate. Can be used.

  Here, it is essential to measure the dimensional change rate in both the MD direction and the TD direction. When imidizing and laminating continuously, the tension is different in the MD direction and the TD direction, so a difference appears in the degree of thermal expansion / contraction and the dimensional change rate is also different. Therefore, a material having a small dimensional change rate is required to have a low change rate in both the MD direction and the TD direction. In the present invention, the dimensional change rate before and after removing the metal foil of the flexible metal-clad laminate, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil are MD direction, It is very preferable that the TD direction is in the range of -0.08 to + 0.08%.

  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 the etching conditions differ depending on the type of metal foil and the shape of the pattern wiring to be formed, the etching process conditions for measuring the dimensional change rate in the present invention are any conventionally known conditions. Also good. Similarly, in the heating process, it is sufficient that heating is performed at 250 ° C. for 30 minutes, and specific conditions are not particularly limited.

  As described above, the flexible metal-clad laminate obtained by the manufacturing method according to the present invention can be mounted with various miniaturized and high-density components by forming a desired pattern wiring by etching the metal foil. It can be used as a flexible wiring board. Of course, the application of the present invention is not limited to this, and it goes without saying that it can be used for various applications as long as it is a laminate including a metal foil.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

  In addition, the glass transition temperature of the thermoplastic polyimide in the synthesis examples, examples and comparative examples, the tensile elastic modulus of the polyimide film and the adhesive film, the thermal expansion coefficient of the adhesive film, the dimensional change rate of the flexible laminate, and the peel strength of the metal foil The evaluation method is as follows.

(Glass-transition temperature)
The glass transition temperature was measured with a DMS200 manufactured by Seiko Instruments Inc. at a temperature rising rate of 3 ° C./min in a temperature range from room temperature to 400 ° C., and the inflection point of the storage elastic modulus was taken as the glass transition temperature.

(Tensile modulus)
The tensile elastic modulus was measured according to JIS K7127 “Plastic tensile property test method”. In addition, the measurement was performed with respect to the MD direction of the film.

(Coefficient of thermal expansion)
The thermal expansion coefficient of the insulating film was 10 ° C. to 330 ° C. at a temperature rising rate of 10 ° C./min under a nitrogen stream using a thermomechanical analyzer (trade name: TMA (Thermomechanical Analyzer) 120C manufactured by Seiko Instruments Inc.). After measuring in the temperature range up to ° C., the average value in the range of 50 to 200 ° C. was determined. The thermal expansion coefficient of the adhesive film was determined as an average value in the range of 200 to 300 ° C.

(Dimensional change rate)
Based on JIS C6481, four holes were formed in the flexible laminate, and the distance of each hole was measured. Next, after carrying out an etching process to remove the metal foil from the flexible laminate, 20 ° C., 60% R.D. H. Left in a constant temperature room for 24 hours. Then, each distance was measured about the said four holes similarly to the etching process front. The measured value of the distance between the holes before removing the metal foil was set as D1, and the measured value of the distance between the holes after removing the metal foil was set as D2, and the dimensional change rate before and after etching was obtained by the following equation.
Dimensional change rate (%) = {(D2-D1) / D1} × 100
Subsequently, the measurement sample after etching was heated at 250 ° C. for 30 minutes, and then 20 ° C. and 60% R.D. H. Left in a constant temperature room for 24 hours. Then, each distance was measured about the said four holes. The measured value of the distance of each hole after heating was set to D3, and the dimensional change rate before and after heating was obtained by the following formula.
Dimensional change rate (%) = {(D3-D2) / D2} × 100
In addition, the said dimensional change rate was measured about both MD direction and TD direction.

(Stripping strength of metal foil: Adhesive strength)
A sample was prepared according to “6.5 Peel Strength” of JIS C6471, and a 5 mm wide metal foil part was peeled off at a peeling angle of 180 degrees and 50 mm / min, and the load was measured.

(Synthesis Example 1; synthesis of polyimide film)
239 kg of N, N-dimethylformamide (hereinafter also referred to as DMF) cooled to 10 ° C., 6.9 kg of 4,4′-oxydianiline (hereinafter also referred to as ODA), p-phenylenediamine (hereinafter also referred to as p-PDA) After dissolving 9.4 kg of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) 6.2 kg, pyromellitic dianhydride (hereinafter also referred to as PMDA). ) 10.4 kg was added and dissolved by stirring for 1 hour. To this, 20.3 kg of benzophenone tetracarboxylic dianhydride (hereinafter also referred to as BTDA) was added and dissolved by stirring for 1 hour.

  A separately prepared DMF solution of PMDA (PMDA: DMF = 0.9 kg: 7.0 kg) was gradually added to the reaction solution, and the addition was stopped when the viscosity reached about 3000 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution having a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3500 poise.

In this polyamic acid solution, a curing agent composed of acetic anhydride / isoquinoline / DMF (weight ratio 4.0 / 1.0 / 4.0) was continuously stirred with a mixer at a weight ratio of 25% with respect to the polyamic acid solution. It was extruded from a T die and cast onto a stainless endless belt running 20 mm below the die. After heating this resin film at 130 ° C. × 100 seconds, the self-supporting gel film is peeled off from the endless belt (volatile content 30% by weight) and fixed to the tenter clip, 300 ° C. × 30 seconds, 400 ° C. × 30 Second, and dried and imidized at 500 ° C. for 30 seconds to obtain a 17 μm polyimide film.
Tensile modulus 7.1 GPa
Thermal expansion coefficient 13ppm / ° C

(Synthesis Example 2: Synthesis of polyimide film)
After dissolving 12.6 kg of ODA and 6.8 kg of p-PDA in 239 kg of DMF cooled to 10 ° C., 15.6 kg of PMDA was added and stirred for 1 hour to dissolve. Subsequently, 12.2 kg of BTDA was added and stirred for 1 hour to dissolve. To this, 5.8 kg of p-phenylenebis (trimellitic acid monoester acid anhydride) (hereinafter also referred to as TMHQ) was added and dissolved by stirring for 2 hours.

  A separately prepared DMF solution of PMDA (PMDA: DMF = 0.9 kg: 7.0 kg) was gradually added to the reaction solution, and the addition was stopped when the viscosity reached about 3000 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution having a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3500 poise.

In this polyamic acid solution, a curing agent composed of acetic anhydride / isoquinoline / DMF (weight ratio 4.0 / 1.0 / 4.0) was continuously stirred with a mixer at a weight ratio of 25% with respect to the polyamic acid solution. It was extruded from a T die and cast onto a stainless endless belt running 20 mm below the die. After heating this resin film at 130 ° C. × 100 seconds, the self-supporting gel film is peeled off from the endless belt (volatile content 30% by weight) and fixed to the tenter clip, 300 ° C. × 30 seconds, 400 ° C. × 30 Second, and dried and imidized at 500 ° C. for 30 seconds to obtain a 16 μm polyimide film.
Tensile modulus 7.6 GPa
Thermal expansion coefficient 9ppm / ° C

(Synthesis Example 3; Synthesis of polyimide film)
In 221 kg of DMF cooled to 10 ° C., 4.9 kg of ODA and 22.3 kg of 4,4′-diaminobenzanilide (hereinafter also referred to as DABA) were dissolved, and then 26.0 kg of PMDA was added and stirred for 1 hour to dissolve.

  A separately prepared DMF solution of PMDA (PMDA: DMF = 0.80 kg: 10.0 kg) was gradually added to the reaction solution, and the addition was stopped when the viscosity reached about 3000 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution having a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3500 poise.

In this polyamic acid solution, a curing agent composed of acetic anhydride / pyridine / DMF (weight ratio 4.0 / 1.0 / 4.0) was continuously stirred with a mixer at a weight ratio of 10% with respect to the polyamic acid solution. It was extruded from a T die and cast onto a stainless endless belt running 20 mm below the die. The resin film was heated at 115 ° C. for 100 seconds, and then the self-supporting gel film was peeled off from the endless belt (volatile content 40% by weight) and fixed to the tenter clip, 200 ° C. × 30 seconds, 300 ° C. × 30 Second, 350 ° C. × 30 seconds, 450 ° C. × 30 seconds, and dried and imidized to obtain a 12 μm polyimide film.
Tensile modulus 10.8GPa
Thermal expansion coefficient 5ppm / ° C

(Synthesis Example 4: Synthesis of polyimide film)
After 21.1 kg of ODA was dissolved in 187 kg of DMF cooled to 10 ° C., 30.6 kg of PMDA was added and dissolved by stirring for 1 hour. To this, 3.78 kg of p-PDA was added and stirred for 1 hour to dissolve.

  A separately prepared DMF solution of p-PDA (PMDA: DMF = 3.78 kg: 38.0 kg) was gradually added to the reaction solution, and the addition was stopped when the viscosity reached about 3000 poise. Stirring was conducted for 1 hour to obtain a polyamic acid solution having a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3400 poise.

In this polyamic acid solution, a curing agent composed of acetic anhydride / isoquinoline / DMF (weight ratio 4.0 / 1.0 / 4.0) was continuously stirred with a mixer at a weight ratio of 25% with respect to the polyamic acid solution. It was extruded from a T die and cast onto a stainless endless belt running 20 mm below the die. After heating this resin film at 130 ° C. × 100 seconds, the self-supporting gel film is peeled off from the endless belt (volatile content 30% by weight) and fixed to the tenter clip, 300 ° C. × 30 seconds, 400 ° C. × 30 Second, and dried and imidized at 500 ° C. for 30 seconds to obtain a 25 μm polyimide film.
Tensile modulus 4.1 GPa
Thermal expansion coefficient 16ppm / ° C

(Synthesis Example 5: Synthesis of polyimide film)
After 25.8 kg of ODA was dissolved in 236 kg of DMF cooled to 10 ° C., 27.4 kg of PMDA was added and stirred for 1 hour to dissolve.

  A separately prepared DMF solution of PMDA (PMDA: DMF = 0.90 kg: 10.2 kg) was gradually added to the reaction solution, and the addition was stopped when the viscosity reached about 3000 poise. Stirring was conducted for 1 hour to obtain a polyamic acid solution having a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3400 poise.

In this polyamic acid solution, a curing agent composed of acetic anhydride / isoquinoline / DMF (weight ratio 4.0 / 1.0 / 4.0) was continuously stirred with a mixer at a weight ratio of 25% with respect to the polyamic acid solution. It was extruded from a T die and cast onto a stainless endless belt running 20 mm below the die. After heating this resin film at 130 ° C. × 100 seconds, the self-supporting gel film is peeled off from the endless belt (volatile content 30% by weight) and fixed to the tenter clip, 300 ° C. × 30 seconds, 400 ° C. × 30 Second, and dried and imidized at 500 ° C. for 30 seconds to obtain a 25 μm polyimide film.
Tensile modulus 3.2 GPa
Coefficient of thermal expansion 32ppm / ° C

(Synthesis Example 6; Synthesis of thermoplastic polyimide precursor)
To a glass flask having a volume of 2000 ml, 780 g of DMF and 117.2 g of bis [4- (4-aminophenoxy) phenyl] sulfone (hereinafter also referred to as BAPS) were added, and while stirring under a nitrogen atmosphere, 3,3 ′ , 4,4′-biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA) was gradually added to 71.7 g. Subsequently, 5.6 g of 3,3 ′, 4,4′-ethylene glycol dibenzoate tetracarboxylic dianhydride (hereinafter also referred to as TMEG) was added and stirred for 30 minutes in an ice bath. A solution in which 5.5 g of TMEG was dissolved in 20 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 3000 poise, addition and stirring were stopped to obtain a polyamic acid solution.

(Synthesis Example 7; Synthesis of thermoplastic polyimide precursor)
780 g of DMF and 115.6 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) were added to a glass flask having a capacity of 2000 ml, and 3,3′4 while stirring under a nitrogen atmosphere. , 4'-biphenyltetracarboxylic dianhydride (BPDA) was gradually added. Subsequently, 3.8 g of ethylenebis (trimellitic acid monoester acid anhydride) (TMEG) was added and stirred for 30 minutes in an ice bath. A solution in which 2.0 g of TMEG was dissolved in 20 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 3000 poise, addition and stirring were stopped to obtain a polyamic acid solution.

(Example 1)
After diluting the polyamic acid solution obtained in Synthesis Example 6 with DMF to a solid content concentration of 10% by weight, the final one side of the thermoplastic polyimide layer (adhesive layer) on both sides of the polyimide film obtained in Synthesis Example 1 Polyamic acid was applied so that the thickness was 4 μm, and then heated at 140 ° C. for 1 minute. Then, it passed through the far-infrared heater furnace with an atmospheric temperature of 390 ° C. for 20 seconds to carry out heating imidization to obtain an adhesive film.
Tensile modulus 6.0 GPa
Thermal expansion coefficient 22ppm / ° C

  By using 18 μm rolled copper foil (BHY-22B-T, manufactured by Japan Energy Co., Ltd.) on both sides of the obtained adhesive film, and further using a protective material (Apical 125 NPI; manufactured by Kanegafuchi Chemical Industry Co., Ltd.) The flexible metal according to the present invention is obtained by continuous thermal lamination under the conditions of polyimide film tension 0.4 N / cm, laminating temperature 380 ° C., laminating pressure 196 N / cm (20 kgf / cm), laminating speed 1.5 m / min. A tension laminate was produced.

(Example 2)
After diluting the polyamic acid solution obtained in Synthesis Example 6 with DMF to a solid content concentration of 10% by weight, the final one side of the thermoplastic polyimide layer (adhesive layer) on both sides of the polyimide film obtained in Synthesis Example 2 Polyamic acid was applied so that the thickness was 5 μm, and then heated at 140 ° C. for 1 minute. Then, it passed through the far-infrared heater furnace with an atmospheric temperature of 390 ° C. for 20 seconds to carry out heating imidization to obtain an adhesive film.
Tensile modulus 6.5 GPa
Coefficient of thermal expansion 21ppm / ° C

  The same operation as Example 1 was performed using the obtained adhesive film, and the flexible metal-clad laminate concerning this invention was produced.

(Example 3)
After diluting the polyamic acid solution obtained in Synthesis Example 6 with DMF until the solid content concentration becomes 10% by weight, the final single side of the thermoplastic polyimide layer (adhesive layer) is formed on both sides of the polyimide film obtained in Synthesis Example 3. Polyamic acid was applied so that the thickness was 6 μm, and then heated at 140 ° C. for 1 minute. Then, it passed through the far-infrared heater furnace with an atmospheric temperature of 390 ° C. for 20 seconds to carry out heating imidization to obtain an adhesive film.
Tensile modulus 9.5 GPa
Coefficient of thermal expansion 20ppm / ° C

  The same operation as Example 1 was performed using the obtained adhesive film, and the flexible metal-clad laminate concerning this invention was produced.

Example 4
An adhesive film was obtained in the same manner as in Example 1 except that the polyamic acid solution obtained in Synthesis Example 7 was used instead of the polyamic acid solution obtained in Synthesis Example 6.
Tensile modulus 6.0 GPa
Thermal expansion coefficient 22ppm / ° C

  The same operation as Example 1 was performed using the obtained adhesive film, and the flexible metal-clad laminate concerning this invention was produced.

(Comparative Example 1)
After diluting the polyamic acid solution obtained in Synthesis Example 6 with DMF until the solid content concentration becomes 10% by weight, the final one side of the thermoplastic polyimide layer (adhesive layer) is formed on both sides of the polyimide film obtained in Synthesis Example 4 Polyamic acid was applied so that the thickness was 2.5 μm, and then heated at 140 ° C. for 1 minute. Then, it passed through the far-infrared heater furnace with an atmospheric temperature of 390 ° C. for 20 seconds to carry out heating imidization to obtain an adhesive film.
Tensile modulus 3.0 GPa
Coefficient of thermal expansion 23ppm / ° C

  Using the resulting adhesive film, the same operation as in Example 1 was performed to produce a flexible metal-clad laminate.

(Comparative Example 2)
An adhesive film was obtained in the same manner as in Comparative Example 1 except that the polyamic acid solution obtained in Synthesis Example 7 was used instead of the polyamic acid solution obtained in Synthesis Example 6.
Tensile modulus 3.0 GPa
Coefficient of thermal expansion 23ppm / ° C

  The same operation as Example 1 was performed using the obtained adhesive film, and the flexible metal-clad laminate concerning this invention was produced.

(Comparative Example 3)
After diluting the polyamic acid solution obtained in Synthesis Example 6 with DMF until the solid content concentration becomes 10% by weight, the final single side of the thermoplastic polyimide layer (adhesive layer) is formed on both sides of the polyimide film obtained in Synthesis Example 5. Polyamic acid was applied so that the thickness was 2.5 μm, and then heated at 140 ° C. for 1 minute. Then, it passed through the far-infrared heater furnace with an atmospheric temperature of 390 ° C. for 20 seconds to carry out heating imidization to obtain an adhesive film.
Tensile modulus 2.4 GPa
Coefficient of thermal expansion 38ppm / ° C

  Using the resulting adhesive film, the same operation as in Example 1 was performed to produce a flexible metal-clad laminate.

(Reference Example 1)
After diluting the polyamic acid solution obtained in Synthesis Example 7 with DMF until the solid content concentration becomes 10% by weight, the final one side of the thermoplastic polyimide layer (adhesive layer) is formed on both sides of the polyimide film obtained in Synthesis Example 4 Polyamic acid was applied so that the thickness was 4 μm, and then heated at 140 ° C. for 1 minute. After the obtained film is cut into a 40 cm square sheet, the four sides of the film are fixed to a pin frame and subjected to heat imidization for 20 seconds in a far infrared heater furnace having an atmospheric temperature of 390 ° C. A film was obtained.

  After cutting the four sides of the resulting adhesive film into a 30 cm square, 18 μm rolled copper foil (BHY-22B-T, manufactured by Japan Energy Co., Ltd.) is provided on both sides of the adhesive film, and protective material (apical) is provided on both sides of the copper foil. 125NPI (manufactured by Kaneka Chemical Industry Co., Ltd.) and Kinyo Board (manufactured by Kinyo Co., Ltd.) on both sides of the protective material, and sandwiched between SUS plates, press temperature 360 ° C., press pressure 294 N / cm (30 kgf / cm), press A single plate press was performed in 5 minutes to produce a flexible metal-clad laminate.

  Table 1 shows the results of evaluating the characteristics of the flexible metal-clad laminate obtained in each of the examples, comparative examples, and reference examples.

  As shown in Reference Example 1 and Comparative Examples 1 to 3, when the properties of the core film are out of the specified range, there is no problem in the single plate press, but the thermal laminating method is affected by the tension and can be obtained. As a result, the dimensional change of the metal-clad laminate was large.

  On the other hand, in Examples 1 to 4 in which all the characteristics are within the predetermined range, the occurrence of dimensional change was suppressed even when produced by the thermal laminating method, and the adhesiveness was not deteriorated.

Claims (5)

An adhesive film in which an adhesive layer containing a thermoplastic polyimide is provided on at least one surface of an insulating film, wherein the insulating film has a tensile modulus in the MD direction of 6.5 to 12 GPa. The adhesive film according to claim 1, wherein the insulating film has a thermal expansion coefficient of 3 to 20 ppm / ° C at 50 to 200 ° C. The adhesive film according to claim 1, wherein the tensile elastic modulus in the MD direction is 5.5 to 11 GPa. A flexible metal-clad laminate obtained by bonding a metal foil to the adhesive film according to claim 1 using a hot roll laminator having a pair of metal rolls. The dimensional change rate before and after removing the metal foil, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil is −0.08 to + 0.08% in both the MD and TD directions The flexible metal-clad laminate according to claim 4, wherein the flexible metal-clad laminate is in the range of.