JP2014040003A - Method for producing multilayer coextrusion polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a multilayer coextrusion polyimide film free from partial sticking of a polyimide layer on a substrate when polyamic acid solutions are flow-cast on the substrate by multilayer coextrusion.SOLUTION: A method is for manufacturing a multilayer polyimide film obtained by flow-casting plural polyamic acid solutions on a substrate by multilayer coextrusion, and laminating a thermoplastic polyimide layer including at least thermoplastic polyimide at least on one side of a non-thermoplastic polyimide layer including at least non-thermoplastic polyimide. An imidation catalyst exists only in a polyamic acid solution having direct contact with a substrate.

Description

  The present invention relates to a method for producing a multilayer coextruded polyimide film that can be suitably used for a flexible printed wiring board.

  In recent years, the demand for various printed circuit boards has increased along with the reduction in weight, size and density of electronic products. ing. The flexible laminate has a structure in which a circuit made of a metal layer is formed on an insulating film such as a polyimide film.

  The flexible metal-clad laminate that is the basis of the flexible wiring board is generally formed of various insulating materials, and a flexible insulating film is used as a substrate, and metal foil is applied to the surface of the substrate via various adhesive materials. Manufactured by a method of bonding by heating and pressure bonding. A polyimide film or the like is preferably used as the insulating film. As the adhesive material, epoxy-type, acrylic-type, etc., thermosetting adhesives are generally used. However, thermosetting adhesives have an advantage that they can be bonded at a relatively low temperature. As the required characteristics such as heat resistance, flexibility and electrical reliability become stricter, it is considered that it is difficult to cope with the three-layer FPC using the thermosetting adhesive. For this reason, 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 multilayer polyimide film for two-layer FPC, a method of producing a multilayer polyimide film by applying a polyamic acid solution on the surface of the polyimide film and drying (imidizing) it can be mentioned. The process of applying and drying (imidizing) the polyamic acid solution on the surface is necessary, and there are cases where the number of processes is increased and the cost is increased (for example, refer to Patent Document 1).

  In addition, as a multilayer polyimide film for two-layer FPC, a method in which a polyamic acid solution is cast on a support at the same time, dried, peeled off from the support, and heat treated to produce a multilayer polyimide film. There was a problem that the polyimide layer in direct contact with the body partially stuck on the support and remained on the support (see, for example, Patent Documents 2 to 3).

JP-A-9-116254 Japanese Patent Laid-Open No. 7-214637 Japanese Patent Laid-Open No. 10-138318

  The present invention has been made in view of the above problems, and its purpose is that when a polyamic acid solution is cast on a support by multilayer coextrusion, a polyimide layer is partially stuck on the support. There is no manufacturing method of a multilayer coextruded polyimide film.

  As a result of intensive studies in view of the above problems, the present inventors have reached the present invention.

  That is, the present invention provides a thermoplastic polyimide layer containing at least a thermoplastic polyimide on at least one surface of a non-thermoplastic polyimide layer containing at least a non-thermoplastic polyimide by casting a plurality of polyamic acid solutions on a support by multilayer coextrusion. It is related with the manufacturing method of the multilayer coextruded polyimide film characterized by including an imidation catalyst only in the polyamic-acid solution which touches a support | substrate directly.

  In the method for producing a multilayer coextruded polyimide film, it is preferable to contain a chemical dehydrating agent and an imidization catalyst only in the polyamic acid solution in direct contact with the support.

  Moreover, it is preferable that the polyamic acid solution which touches the said support body directly is a polyamic acid solution which becomes a thermoplastic polyimide layer.

  In addition, 60% or more of the total number of moles of the acid dianhydride monomer and the diamine monomer constituting the thermoplastic polyimide is a single amount of the acid dianhydride monomer and the diamine constituting the non-thermoplastic polyimide. It is preferable that it is a body.

  The diamine constituting the thermoplastic polyimide preferably contains 2,2-bis [4- (4-aminophenoxy) phenyl] propane as an essential component.

  Moreover, it is preferable that the polyamic acid used as the said non-thermoplastic polyimide layer is a polyamic acid which is a precursor of the non-thermoplastic polyimide which has a thermoplastic block component in a molecule | numerator.

  According to the present invention, there is provided a method for producing a multilayer coextruded polyimide film in which, when a polyamic acid solution is cast on a support by multilayer coextrusion, there is no partial sticking of a polyimide layer on the support.

  One embodiment of the present invention will be described below.

  In the present invention, a plurality of polyamic acid solutions are cast on a support by multilayer coextrusion, and at least one surface of a non-thermoplastic polyimide layer containing non-thermoplastic polyimide is provided with a thermoplastic polyimide layer containing at least thermoplastic polyimide. The present invention relates to a method for producing a laminated multilayer polyimide film, wherein the imidization catalyst is contained only in a polyamic acid solution in direct contact with a support.

  The non-thermoplastic polyimide in the present invention generally means a polyimide that does not soften or show adhesiveness even when heated. In the present invention, a film obtained by forming a non-thermoplastic film alone, heated at 450 ° C. for 1 minute, not wrinkled or stretched, retaining its shape, or DSC (differential) Scanning calorimetry) means a polyimide having substantially no glass transition temperature.

  The thermoplastic polyimide generally means a polyimide having a glass transition temperature by DSC (differential scanning calorimetry). The thermoplastic polyimide in the present invention refers to one having a glass transition temperature of 150 ° C to 350 ° C.

  The aromatic acid dianhydride used as a raw material for the non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer of the multilayer polyimide film is not particularly limited, but pyromellitic dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2', 3,3 ' -Biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic 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-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic acid Dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, p-phenylenebis (trimellitic acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis A mixture containing (trimellitic acid monoester anhydride) and derivatives thereof, which are mixed alone or in an arbitrary ratio, can be preferably used.

  Among them, it is selected from the group consisting of pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride. Preferably, it is at least one acid dianhydride, and in terms of solvent solubility during production, pyromellitic dianhydride and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride are further included. preferable.

  The aromatic diamine used as a raw material for the non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer of the multilayer polyimide film is not particularly limited, but 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4 '-Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, p-phenylenediamine, 4,4'-diamino Diphenylpropane, 4,4'-diaminodiphenylmethane, benzidine, 3,3'-dichlorobenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 4, 4'-diaminodiphenyl ether, 3,3'-diaminodi Phenyl ether, 3,4′-diaminodiphenyl ether, 1,5-diaminonaphthalene, 4,4′-diaminodiphenyldiethylsilane, 4,4′-diaminodiphenylsilane, 4,4′-diaminodiphenylethylphosphine oxide, 4, 4'-diaminodiphenyl N-methylamine, 4,4'-diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene, 1,2-diaminobenzene, 2 , 2-bis [4- (4-aminophenoxy) phenyl] propane and derivatives thereof, and the like, and a mixture of these alone or in an arbitrary ratio can be preferably used.

  Among them, as the diamine constituting the non-thermoplastic polyimide, it is preferable to use 2,2-bis [4- (4-aminophenoxy) phenyl] propane in terms of forming the thermoplastic block, and the linear expansion coefficient and the strength are increased. In terms of control, it is preferable to use p-phenylenediamine or 4,4′-diaminodiphenyl ether.

  It should be noted that the non-thermoplastic polyimide contains a thermoplastic block component, that is, the polyamic acid that becomes the non-thermoplastic polyimide layer is a polyamic acid that is a precursor of the non-thermoplastic polyimide having a thermoplastic block component in the molecule. A certain thing is preferable at the point which can improve the adhesiveness of a non-thermoplastic polyimide and a thermoplastic polyimide.

  The aromatic dianhydride used as a raw material for the thermoplastic polyimide contained in the thermoplastic polyimide layer of the multilayer polyimide film is not particularly limited, but pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic Acid dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyl Tetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic 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, -Bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic acid dianhydride Bis (3,4-dicarboxyphenyl) sulfone dianhydride, p-phenylene bis (trimellitic acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (tri Mellitic acid monoester acid anhydride) and derivatives thereof, and a mixture of these alone or in an arbitrary ratio can be preferably used.

  Among them, it is selected from the group consisting of pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride. At least one kind of acid dianhydride is preferable, and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is used in terms of increasing the peel strength of the copper foil of the flexible metal-clad laminate. Preferably, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic acid dihydrate are used in order to improve solder heat resistance while increasing the copper foil peeling strength of the flexible metal-clad laminate. It is preferable to use an anhydride in combination.

  Although the aromatic diamine used as a raw material of the thermoplastic polyimide contained in the thermoplastic polyimide layer of the multilayer polyimide film is not particularly limited, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4′- Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, p-phenylenediamine, 4,4'-diaminodiphenylpropane 4,4'-diaminodiphenylmethane, benzidine, 3,3'-dichlorobenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4 ' -Diaminodiphenyl ether, 3,3'-diaminodiphe Ether, 3,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4 '-Diaminodiphenyl N-methylamine, 4,4'-diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene, 1,2-diaminobenzene, 2, Examples thereof include 2-bis [4- (4-aminophenoxy) phenyl] propane and derivatives thereof, and a mixture of these alone or in an arbitrary ratio can be preferably used.

  Among these, 2,2-bis [4- (4-aminophenoxy) phenyl] propane constituting thermoplastic polyimide is preferable in terms of improving the peel strength of the metal foil of the metal foil-clad laminate.

  A multilayer polyimide film is a non-thermoplastic polyimide layer with a thermoplastic polyimide layer formed on at least one side. A non-thermoplastic polyimide layer with a thermoplastic polyimide layer formed on both sides is a double-sided metal film. This is preferable in that a laminated board can be manufactured, and the flexible printed wiring board can be reduced in weight, size, and density.

  As a method for producing a multilayer polyimide film, a multilayer polyimide film is produced by simultaneously casting a multilayer polyamic acid on a support by multilayer coextrusion. At that time, the imidization catalyst is contained only in the polyamic acid solution in direct contact with the support. By including an imidization catalyst, imidation of the polyamic acid that is in direct contact with the support proceeds, self-supporting properties are developed, film strength is increased, and no partial sticking is left on the support. It becomes possible to peel off the multilayer gel film. As the imidization reaction proceeds, the solvent oozes out due to the difference in solvent solubility between the polyamic acid and the polyimide, and the multilayer gel film can be easily peeled off from the support. For this reason, it is useful to include an imidization catalyst in the polyamic acid solution that is in direct contact with the support. Furthermore, some of the imidization catalysts in the polyamic acid that are in direct contact with the support come out in the thickness direction upon heating. At that time, the imidization reaction proceeds in other polyamic acid solutions, and the reaction is efficiently performed. Can proceed. In addition, reaction can be advanced more efficiently by using an imidation catalyst and a chemical dehydrating agent together.

  Even if the polyamic acid solution in direct contact with the support is a polyamic acid solution of a non-thermoplastic polyimide layer or a polyamic acid solution of a thermoplastic polyimide layer, the effect is recognized. The effect is noticeable when touching directly.

  In multilayer coextrusion, a polyamic acid solution of a thermoplastic polyimide layer is cast on a support, and the multilayer gel film obtained by drying on the support has a drying temperature on the support that is the glass transition temperature of the thermoplastic polyimide. Even if the temperature is lower, if the polyamic acid skeleton partially remains, the glass transition temperature is lowered, and the glass gel is easily softened depending on the residual solvent amount of the multilayer gel film. As a result, by simply drying on the support, the multi-layer gel film does not exhibit the strength to withstand at least partially peeling from the support, and the multilayer gel film of thermoplastic polyimide is partially attached to the support. Sometimes it stayed on. Therefore, when the polyamic acid solution of the thermoplastic polyimide layer is in direct contact with the support, the polyamic acid solution that becomes the thermoplastic polyimide layer contains an imidization catalyst, thereby expressing strength in the multilayer gel film of thermoplastic polyimide. It is possible to reduce adhesion of the thermoplastic polyimide multilayer gel film to the support when it is peeled from the support. Moreover, by using a chemical dehydrating agent in combination with the imidization catalyst, the imidization reaction can proceed more easily, and the strength of the multilayer gel film can be further increased.

  The content of the imidization catalyst in the polyamic acid solution in direct contact with the support is 0.05 to 2.0 mol with respect to 1 mol of the amic acid unit in the polyamic acid contained in the solution containing the imidization catalyst. Preferably, 0.05 to 1.0 mol is more preferable, and 0.1 to 0.8 mol is particularly preferable in terms of balancing the strength of the gel film when peeled from the support and the peelability from the support.

  The content of the chemical dehydrating agent is preferably 0.5 to 4.5 mol with respect to 1 mol of the amic acid unit in the polyamic acid contained in the solution containing the chemical dehydrating agent and the imidization catalyst. 1.0-4.0 mol is more preferable at the point which can balance the intensity | strength of the gel film at the time of peeling from a film, and the peelability from a support body.

  With regard to the imidization time, it suffices to take a sufficient time for the imidization and drying to be substantially completed, and it is not limited uniquely. In general, a chemical curing method using a chemical dehydrating agent is used. In the case of employing a heat curing method that does not use a chemical dehydrating agent, the time is appropriately set in the range of 60 to 1800 seconds.

  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, the metal-clad laminate produced using the substrate for metal-clad laminate may deteriorate in dimensional characteristics because it is heated at a high temperature with a strong tension applied.

  The thickness of the multilayer polyimide film is preferably 7.5 μm or more and 125 μm or less. The thickness of the thermoplastic polyimide layer on at least one surface of the non-thermoplastic polyimide layer in the multilayer polyimide film is preferably 1.7 μm or more and 35 μm or less, more preferably 1.7 μm or more and 10 μm or less, and more preferably 1.7 μm or more and 8 μm or less. Is particularly preferred. If it is less than 1.7 μm, the adhesion may be deteriorated depending on the roughness of the surface of the metal foil. On the other hand, when the thickness is larger than 35 μm, the dimensional change rate after etching the metal foil of the metal foil-clad laminate may become larger on the minus side.

  Next, the adhesion between the thermoplastic polyimide layer and the non-thermoplastic polyimide layer constituting the multilayer polyimide film will be described.

  When the structures of the thermoplastic polyimide and the non-thermoplastic polyimide are different, for example, less than 60% of the total number of moles of acid dianhydride monomer and diamine monomer constituting the thermoplastic polyimide is non-thermoplastic polyimide. When the acid dianhydride monomer and the diamine monomer are the same, the multilayer gel film of thermoplastic polyimide is easily peeled off from the multilayer gel film of non-thermoplastic polyimide, and the multilayer gel film of thermoplastic polyimide May remain partially attached to the support. This is considered to be due to the fact that the polyamic acid of the non-thermoplastic polyimide layer is larger than the imidization rate of the polyamic acid of the thermoplastic polyimide layer. However, by including an imidization catalyst in the polyamic acid solution of thermoplastic polyimide that is in direct contact with the support, the imidization rate of the polyamic acid of the non-thermoplastic polyimide approaches the imidization rate of the polyamic acid of the thermoplastic polyimide. The adhesion between the non-thermoplastic polyimide layer and the thermoplastic polyimide layer is improved, and the gel film portion of the thermoplastic polyimide is reduced from sticking to the support. By using in combination with an imidization catalyst and a chemical dehydrating agent, the imidization rate becomes closer, and the thermoplastic polyimide gel film sticks to the support further.

  When the structures of the thermoplastic polyimide and non-thermoplastic polyimide are similar, for example, 60% or more of the total number of moles of acid dianhydride monomer and diamine monomer constituting the thermoplastic polyimide is non-thermoplastic polyimide. When the acid dianhydride monomer and the diamine monomer are the same, the structure is similar, so the imidation rate of the polyamic acid of the non-thermoplastic polyimide and the imidation of the polyamic acid of the thermoplastic polyimide Although the difference in speed is originally small and the thermoplastic polyimide gel film part is difficult to stick to the support, the thermoplastic polyimide gel film part is partially attached to the support when the line speed is increased to improve production efficiency. It sometimes sticked to. However, by including an imidization catalyst in the polyamic acid solution of thermoplastic polyimide that is in direct contact with the support, the imidization rate of the polyamic acid of the thermoplastic polyimide is increased, and the solvent soaks between the support and the multilayer gel film. The multilayer gel film is smoothly peeled off from the support and the gel film portion of the thermoplastic polyimide is reduced from sticking to the support. By using in combination with an imidization catalyst and a chemical dehydrating agent, the imidization rate becomes closer, and the thermoplastic polyimide gel film sticks to the support further.

  Further, 60% or more of the total number of moles of the acid dianhydride monomer and diamine monomer constituting the thermoplastic polyimide is the acid dianhydride monomer and diamine monomer constituting the non-thermoplastic polyimide. In this case, the adhesion between the thermoplastic polyimide layer and the non-thermoplastic polyimide layer is increased, and the solder heat resistance is improved. However, the thermoplastic polyimide layer needs to have thermoplasticity in order to exhibit the copper foil peeling strength in the case of a metal foil-clad laminate.

  Here, 60% or more of the total number of moles of the acid dianhydride monomer and diamine monomer constituting the thermoplastic polyimide is the acid dianhydride monomer and diamine monomer constituting the non-thermoplastic polyimide. With being based on the total number of moles (total number of moles) of the acid dianhydride monomer and diamine monomer constituting the thermoplastic polyimide, the acid dianhydride and diamine used in the thermoplastic polyimide, Same as acid dianhydride and dianmian used in non-thermoplastic polyimide, the ratio of the number of moles (same mole number) of acid dianhydride monomer and diamine monomer is 60% or more. ) / (Total number of moles).

  If the same number of moles of the acid dianhydride monomer and the diamine monomer constituting the thermoplastic polyimide is 60% or more of the total number of moles, the multilayer gel film of thermoplastic polyimide will stick to the support. However, it is preferably 70% or more, more preferably 80% or more. Further, the upper limit of the ratio is preferably 99% or less, and more preferably 98% or less.

  The method for producing a multilayer polyimide film according to the present invention comprises supplying a polyamic acid solution simultaneously to two or more multilayer dies by multilayer coextrusion, and forming a drum, an endless belt as at least two layers of thin film bodies from the discharge port of the die. And then heated at 60 ° C. to 150 ° C. on the support, and then peeled off the multilayer gel film from the support and heated at a high temperature of 150 ° C. or higher to form at least a non-thermoplastic polyimide layer. There is a method for producing a multilayer polyimide film in which a thermoplastic polyimide layer is laminated on one side. There is no problem if the number of layers is at least 2 or more, but it is preferably 3 layers in order to suppress curling of the obtained multilayer polyimide film. Multi-layer coextrusion is preferable in terms of productivity and also in terms of moisture absorption solder heat resistance. This is not clear, but the polyamic acid of the non-thermoplastic polyimide layer and the polyamic acid of the thermoplastic polyimide layer are extruded at the same time. It is presumed that the integrity of the thermoplastic polyimide layer is improved.

  Below, the manufacturing method of a multilayer polyimide film by multilayer coextrusion is described.

  To describe a generally used method, the solution extruded from two or more multilayer dies is continuously extruded onto a smooth support, and then a multilayer thin film solvent on the support. A multilayer gel film having a self-supporting property is obtained by volatilizing at least a part of the film.

  The multilayer polyamic acid on the support is preferably heated at a maximum temperature of 100 to 200 ° C.

Further, the multilayer gel film is peeled off from the support, and finally the multilayer gel film is sufficiently heated at a high temperature (250 to 600 ° C.) to substantially remove the solvent and imidize. A multilayer polyimide film can be obtained by making it advance completely. The multilayer gel film peeled off from the support is in the middle stage of curing from polyamic acid to polyimide, has a self-supporting property, and has the formula (1)
(AB) × 100 / B (1)
In formula (1), A and B represent the following.
A: Weight of the multilayer film B: The volatile content calculated from the weight after heating the multilayer film at 450 ° C. for 20 minutes is in the range of 5 to 200% by weight, preferably 10 to 100% by weight, more preferably 30 to 30%. It is in the range of 80% by weight. It is preferable to use a multilayer gel film in this range, which is preferable in that it can suppress problems such as film breakage, uneven color tone due to uneven drying, and characteristic variations during baking. Further, for the purpose of improving the melt fluidity of the thermoplastic polyimide layer, the imidization rate may be intentionally lowered and / or the solvent may be left.

  The support according to the present invention casts a multilayer liquid film extruded from a multilayer die, and heat-drys the multilayer liquid film on the support to give self-supporting property. The shape of the support is not particularly limited, but in consideration of the productivity of the adhesive film, it is preferably a drum shape or a belt shape. The material of the support is not particularly limited, and examples thereof include metal, plastic, glass, porcelain, etc., preferably metal, and more preferably SUS material having excellent corrosion resistance. Further, metal plating such as Cr, Ni, Sn may be performed.

  As the above-mentioned multilayer die, those having various structures can be used. For example, a T die for forming a multilayer film can be used. In addition, any conventionally known structure can be suitably used, and feed block T dies and multi-manifold T dies are exemplified as particularly suitable ones.

  As the preferred solvent for synthesizing the polyamic acid in the present invention, any solvent can be used as long as it dissolves the polyamic acid, but amide solvents, that is, N, N-dimethylformamide, N, N-dimethylacetamide N-methyl-2-pyrrolidone and the like can be exemplified. Of these, N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.

In the present invention, any monomer addition method may be used for the polymerization of the non-thermoplastic polyamic acid. As typical polymerization methods, the following methods may be mentioned. 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 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. Subsequently, a method of polymerizing with an aromatic diamine compound so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps,
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 mixture of substantially equimolar aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent,
And so on. These methods may be used singly or in combination.

Especially, it is preferable that the polyamic acid of a non-thermoplastic polyimide layer is obtained by the following process (a)-(c).
(A) Aromatic dianhydride and an excess molar amount of aromatic diamine are reacted in an organic polar solvent to obtain a prepolymer having amino groups at both ends. (B) Subsequently, (C) Furthermore, aromatic dianhydride is added and polymerized so that the aromatic dianhydride and aromatic diamine are substantially equimolar in all steps, and polyamic acid is added. Obtain a solution.

  Among the above methods, the prepolymer obtained in (a) is preferably a thermoplastic block component. Next, a method for determining whether the prepolymer is a thermoplastic block component will be described.

(Judgment method of thermoplastic block component)
Correct the acid dianhydride and diamine used in the preparation of the prepolymer to equimolar amounts (if there are multiple types of acid dianhydrides used, the ratio is fixed, and the diamine used is multiple types) The ratio was fixed.) The obtained polyamic acid solution was cast on an aluminum foil using a comma coater, heated at 130 ° C. for 100 seconds, and then a self-supporting gel film was formed from the aluminum foil. Peel off and fix to metal frame. Thereafter, when the film was softened or melted when heat-treated at 300 ° C. for 20 seconds and 450 ° C. for 1 minute, it was determined as a thermoplastic block component when the appearance was deformed.

  The acid dianhydride and diamine that can serve as the thermoplastic block component are not particularly limited. Examples of the acid dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4, It is preferable to use 4'-benzophenone tetracarboxylic dianhydride as an essential component. As the diamine, it is preferable to use 2,2-bis [4- (4-aminophenoxy) phenyl] propane as an essential component.

  A method for producing a thermoplastic polyamic acid of a thermoplastic polyimide is as follows: (a) an aromatic acid dianhydride and an excess molar amount of an aromatic diamine are reacted in an organic polarity, and amino groups are formed at both ends. (B) Subsequently, the aromatic dianhydride is added and polymerized so that the ratio of the aromatic dianhydride to the aromatic diamine in all the steps becomes a predetermined ratio. It is preferable. In (b), there are a method of adding an aromatic acid dianhydride, a method of adding a powder, a method of adding an acid solution in which an acid dianhydride is dissolved in an organic polar solvent in advance, and the reaction is uniform. In view of easy progress, a method of adding an acid solution is preferable.

  The solid component concentration during the polymerization is preferably 10 to 30% by weight. The solid component concentration can be determined by the polymerization rate and the polymerization viscosity. The polymerization viscosity can be set according to the case where the polyamic acid solution of thermoplastic polyimide is applied to the support film, or when it is coextruded with non-thermoplastic polyimide. The polymerization viscosity is preferably 100 poise or less at a component concentration of 14% by weight. In the case of coextrusion, for example, the polymerization viscosity is preferably 100 poise to 1200 poise at a solid component concentration of 14% by weight, and 150 poise to 800 poise is preferable because the film thickness of the resulting multilayer polyimide film can be made uniform. The aromatic dianhydride and aromatic diamine described above can be used by changing the order in consideration of the properties and productivity of the multilayer polyimide film.

  In addition, a filler can be added for the purpose of improving various properties of the film such as slidability, thermal conductivity, conductivity, and corona resistance. The filler is not particularly limited, and preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

When a filler is added to improve the slidability of the film, the particle size is 0.1 to 10 μm, preferably 0.1 to 5 μm. If the particle diameter is below this range, the effect of improving the slidability is hardly exhibited, and if it exceeds this range, it tends to be difficult to produce a high-definition wiring pattern. Furthermore, in this case, the dispersion state of the filler is also important, and it is preferable that the aggregate of fillers of 20 μm or more is 50 / m ² or less, preferably 40 / m ² or less. If there are more filler aggregates of 20 μm or more than this range, it may cause repellency when the adhesive is applied, or decrease the adhesion area when creating a high-definition wiring pattern, and the insulation reliability of the flexible printed circuit board itself Tend to drop.

Addition of the filler is, for example,
(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 (3) A dispersion containing fillers is prepared, and this is added to polyamide Method of mixing with acid organic solvent solution (4) Any method such as a method of dispersing by bead mill or the like may be used, but a method of mixing a dispersion containing filler with a polyamic acid solution, particularly a method of mixing just before film formation It 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. Moreover, in order to disperse | distribute a filler favorably and stabilize a dispersion state, a dispersing agent, a thickener, etc. can also be used in the range which does not affect a film physical property.

  Polyimide is obtained by a dehydration conversion reaction from a polyimide precursor, that is, a polyamic acid. As a method for performing the conversion reaction, there are two methods of a thermal curing method using only heat and a chemical curing method using a chemical dehydrating agent. Is the most widely known. However, since it is excellent in productivity, it is more preferable to employ a chemical curing method. In both the thermal curing method and the chemical curing method, it is preferable to use an imidization catalyst in terms of advancing the imidization reaction quickly.

  A chemical dehydrating agent is a dehydrating ring-closing agent for polyamic acid, and the main components thereof are aliphatic acid anhydride, aromatic acid anhydride, N, N′-dialkylcarbodiimide, lower aliphatic halide, halogenated lower fat. An aromatic acid anhydride, an aryl sulfonic acid dihalide, a thionyl halide, or a mixture of two or more thereof can be preferably used. Of these, aliphatic acid anhydrides and aromatic acid anhydrides work particularly well. The imidation catalyst is a component having an effect of promoting the dehydration ring-closing action of the curing agent on the polyamic acid. For example, an aliphatic tertiary amine, an aromatic tertiary amine, or a heterocyclic tertiary amine is used. Can do. Of these, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, or β-picoline are preferred. Furthermore, introduction of an organic polar solvent into a solution composed of a chemical dehydrating agent and an imidization catalyst can be appropriately selected.

  It is preferable that the manufacturing method of the flexible metal-clad laminate concerning this invention includes the process of bonding metal foil to the said multilayer polyimide film. The copper foil used in the flexible metal laminate may have a thickness of 1 to 25 μm, and either a rolled copper foil or an electrolytic copper foil may be used.

  As a method for laminating the multilayer polyimide film and the metal foil, for example, a hot 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 process of bonding the multilayer polyimide film and the metal foil together by thermal lamination is hereinafter referred to as “thermal lamination process”.

  The specific configuration of the means for carrying out the thermal laminating (hereinafter also referred to as “thermal laminating means”) is not particularly limited, but in order to improve the appearance of the resulting laminate, the pressure surface It is preferable to arrange a protective material between the metal foil and the metal foil.

  Examples of the protective material include materials that can withstand the heating temperature in the heat laminating process, for example, heat-resistant plastics such as non-thermoplastic polyimide films, metal foils such as copper foil, aluminum foil, and SUS foil. Among these, a non-thermoplastic polyimide film or a film made of a thermoplastic polyimide having a glass transition temperature (Tg) higher by 50 ° C. or more than the laminating temperature is preferably used from the viewpoint of excellent balance of heat resistance, reusability and the like. When using thermoplastic polyimide, adhesion of the thermoplastic polyimide to the roll can be prevented by selecting one that satisfies the above conditions.

  In addition, if the thickness of the protective material is thin, the role of buffering and protection 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.

  Further, when the laminate temperature is high, if the protective material is used as it is for the laminate, the appearance and dimensional stability of the resulting flexible metal-clad laminate may not be sufficient due to rapid thermal expansion. Therefore, it is preferable to preheat the protective material before lamination. As described above, when the protective material is preheated and then laminated, since the thermal expansion of the protective material is finished, the appearance and dimensional characteristics of the flexible metal-clad laminate are suppressed.

  Examples of the preheating means include a method of bringing a protective material into contact with a heating roll. The contact time is preferably 1 second or longer, and more preferably 3 seconds or longer. When the contact time is shorter than the above, since the lamination is performed without the thermal expansion of the protective material, the thermal expansion of the protective material occurs during the lamination, and the appearance and dimensional characteristics of the resulting flexible metal-clad laminate are deteriorated. There are things to do. The distance at which the protective material is held on the heating roll is not particularly limited, and may be appropriately adjusted from the diameter of the heating roll and the contact time.

  The heating method of the material to be laminated in the heat laminating means is not particularly limited, and 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, etc., is adopted. A heating means can be used. Similarly, the method for pressurizing the material to be laminated in the thermal laminating means is not particularly limited, and is a conventionally known method capable of applying a predetermined pressure such as a hydraulic method, a pneumatic method, a gap pressure method, or the like. A pressurizing means adopting the method 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 thermoplastic polyimide contained in the thermoplastic polyimide layer of the multilayer polyimide film + 50 ° C. or higher. Tg + 100 ° C. or higher of the thermoplastic polyimide contained in the plastic polyimide layer is more preferable. If it is Tg + 50 degreeC or more temperature, a multilayer polyimide 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.

  In particular, it is preferable that the polyimide film used as the core of the multilayer polyimide film of the present invention is designed so that the thermal stress can be effectively relieved when laminating, and flexible with excellent dimensional stability. A metal-clad laminate can be obtained with high productivity.

  The contact time with the heating roll is preferably 0.1 seconds or more, more preferably 0.2 seconds or more, and particularly preferably 0.5 seconds or more. When the contact time is shorter than the above range, the relaxation effect may not be sufficiently generated. The upper limit of the contact time is preferably 5 seconds or less. Even if the contact is made for longer than 5 seconds, the relaxation effect is not increased, and it is not preferable because a decrease in the laminating speed and restrictions on the line handling occur.

  Moreover, even if it is brought into contact with a heating roll after lamination and subjected to slow cooling, the difference between the flexible metal-clad laminate and room temperature is still large, and the residual strain may not be alleviated. Therefore, it is preferable that the flexible metal-clad laminate after being brought into contact with the heating roll and gradually cooled is subjected to the post-heating step with the protective material still disposed. The tension at this time is preferably in the range of 1 to 10 N / cm. Moreover, it is preferable to make the atmospheric temperature of post-heating into the range of (temperature -200 degreeC)-(lamination temperature +100 degreeC).

  The “atmosphere temperature” here refers to the outer surface temperature of the protective material in close contact with both surfaces of the flexible metal-clad laminate. The actual temperature of the flexible metal-clad laminate varies somewhat depending on the thickness of the protective material, but if the temperature of the surface of the protective material is within the above range, the effect of post-heating can be exhibited. The outer surface temperature of the protective material can be measured using a thermocouple or a thermometer.

  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 thermal laminating process, that is, the laminating pressure, there is an advantage that the laminating temperature can be lowered and the laminating speed can be increased. However, in general, when the laminating pressure is too high, the dimensions of the obtained laminate are obtained. Changes tend to get worse. On the other hand, when the lamination pressure is too low, the adhesive strength of the metal foil of the resulting laminate is reduced. Therefore, the laminating 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 laminating temperature, laminating speed, and laminating pressure can be improved, and productivity can be further improved.

  The adhesive film tension in the laminating step is preferably in the range of 0.01 to 4 N / cm, more preferably in the range of 0.02 to 2.5 N / cm, and 0.05 to 1. A range of 5 N / cm is particularly preferable. When the tension is below the above range, sagging or meandering occurs during conveyance of the laminate, and it is not uniformly fed to the heating roll, so that it may be difficult to obtain a flexible metal-clad laminate having a good appearance. On the other hand, if it exceeds the above range, the influence of tension becomes so strong that it cannot be relaxed by controlling the Tg and storage 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. Further, in this thermal laminating apparatus, a laminated material feeding means for feeding the laminated material may be provided before the thermal laminating means, or a laminated material winding for winding the laminated material is taken after the thermal laminating means. Means may be provided. 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. For example, a known roll shape capable of winding an adhesive film, a metal foil, or a laminated sheet to be obtained. 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.

  The peel strength between the multilayer polyimide film and the metal foil of the flexible metal-clad laminate is preferably 10 N / cm or more.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples. In addition, the evaluation method of the peeling strength of a multilayer polyimide film and metal foil and solder heat resistance in a synthesis example, an Example, and a comparative example is as follows.

(Method for producing metal-clad laminate)
Laminated copper foil (BHY-22B-T; manufactured by Nikko Metal) on both sides of the multilayer polyimide film, and protective materials (Apical 125NPI; manufactured by Kaneka) are arranged on both sides of the multilayer polyimide film using a hot roll laminator. Thermally laminating was carried out under the conditions of a temperature of 380 ° C., a laminating pressure of 294 N / cm (30 kgf / cm), and a laminating speed of 1.0 m / min to produce a flexible metal-clad laminate.

(Stripping strength of metal foil)
A sample was prepared according to “6.5 peel strength” of JIS C6471, and a 3 mm wide metal foil part was peeled off at a peeling angle of 180 degrees and 50 mm / min, and the load was measured.

(Solder heat resistance evaluation)
A test piece of 3 cm × 3 cm was cut out from the flexible metal-clad laminate, and solder heat resistance evaluation during normal state and moisture absorption was performed. In the normal state, the test piece was adjusted at 23 ° C./55% RH for 24 hours, and then allowed to stand in a float for 30 seconds using a warmed solder bath. Thereafter, the copper foil on the side touching the solder bath was etched to check for swelling. The temperature of the solder bath without blistering is shown in Table 1. Further, at the time of moisture absorption, after adjusting for 24 hours at 85 ° C./85% RH, a warmed solder bath was used and left standing for 30 seconds in a float. Thereafter, the copper foil on the side touching the solder bath was etched to check for swelling. The temperature of the solder bath without blistering is shown in Table 1.

The abbreviations of monomers used in the synthesis examples are shown below.
DMF: N, N-dimethylformamide BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl] propane ODA: 4,4′-diaminodiphenyl ether PDA: p-phenylenediamine BPDA: 3, 3 ′, 4 , 4'-biphenyltetracarboxylic dianhydride BTDA: 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride PMDA: pyromellitic dianhydride Below, a synthesis example of a polyamic acid solution is shown. .

(Synthesis Example 1)
BAPP (57.3 g: 0.140 mol) and ODA (18.6 g: 0.093 mol) were dissolved in DMF (1173.5 g) cooled to 10 ° C. BTDA (30.0 g: 0.093 mol) and PMDA (25.4 g: 0.116 mol) were added thereto, and the mixture was stirred uniformly for 30 minutes to obtain a prepolymer.
After PDA (25.2 g: 0.233 mol) was dissolved in this solution, PMDA (46.9 g: 0.215 mol) was dissolved, and carefully prepared separately with a 7.2 wt% DMF solution of PMDA prepared separately. 0.1 g (PMDA: 0.038 mol) was added, and the addition was stopped when the viscosity reached about 2500 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution having a rotational viscosity at 23 ° C. of 2600 poise.
The polyamic acid solution synthesized in equimolar amounts of acid dianhydride and diamine, which was used when producing the prepolymer, was cast on an aluminum foil using a comma coater, and 130 ° C. × 100 seconds. After heating, the self-supporting gel film was peeled off from the aluminum foil and fixed to the metal frame. Thereafter, when heat treatment was performed at 300 ° C. for 20 seconds and 450 ° C. for 1 minute, the film was melted and the appearance was deformed. Therefore, the block component of Synthesis Example 1 was determined to be a thermoplastic block component.

(Synthesis Example 2)
BPDA (85.6 g: 0.291 mol) was added to 937.6 g of N, N-dimethylformamide (DMF), then BAPP (118.6 g: 0.289 mol) was added, and the solid component concentration was about 17%. A polyamic acid solution having a viscosity of 800 poise at 23 ° C. was obtained. Thereafter, DMF was added to obtain a polyamic acid solution having a solid component concentration of 14% by weight.

(Synthesis Example 3)
BAPP (118.6 g: 0.289 mol) was dissolved in 843.4 g of N, N-dimethylformamide (DMF). BPDA (12.7 g: 0.043 mol) was added thereto, heated to 50 ° C., cooled to 10 ° C., and PMDA (65.9 g: 0.223 mol) was added to obtain a prepolymer.
Thereafter, 48.6 g (PMDA: 0.021 mol) of 7 wt% DMF solution of PMDA which was separately prepared was carefully added to obtain a polyamic acid solution having a solid component concentration of about 17% and an 800 poise viscosity at 23 ° C. . Thereafter, DMF was added to obtain a polyamic acid solution having a solid component concentration of 14% by weight.

Example 1
Using a multi-manifold three-layer coextrusion three-layer die with a lip width of 200 mm, the polyamic acid solution obtained in Synthesis Example 2 / the polyamic acid solution obtained in Synthesis Example 1 / the polyamic acid solution obtained in Synthesis Example 2 Extruded and cast on an aluminum foil with a three-layer structure in the order of Then, after heating this three-layer film at 150 ° C. × 100 seconds, the three-layer gel film having self-supporting properties is peeled off and fixed to a metal frame, 250 ° C. × 40 seconds, 300 ° C. × 60 seconds, 350 Drying and imidization at ℃ × 60 seconds, 370 ° C × 30 seconds, and the thickness of the thermoplastic polyimide layer / non-thermoplastic polyimide layer / thermoplastic polyimide layer is 2.7 μm / 12.6 μm / 2.7 μm. A film was obtained.
At this time, the polyamic acid solution obtained in Synthesis Example 2 was prepared by adding only the polyamic acid solution on the surface directly in contact with the support to the acetic anhydride / isoquinoline with respect to 100 g of this polyamic acid solution immediately before being charged into the three-layer die. 20 g of a curing agent consisting of / DMF (weight ratio 33.0 g / 8.3 g / 58.6 g) was added and mixed with a mixer.
After producing a metal-clad laminate using a three-layer polyimide film, the peel strength of the metal foil and the solder heat resistance were measured. The results are summarized in Table 1.
In addition, in the table | surface, the thermoplastic polyimide layer of the surface which touches directly on a support body is described as B surface, and the thermoplastic polyimide layer of the opposite side is described as A surface.

(Comparative Example 1)
The same procedure as in Example 1 was performed, except that the chemical dehydrating agent and the imidization catalyst were not added to the polyamic acid solution of Synthesis Example 2. There was a trace of partial peeling in the B-side thermoplastic polyimide layer that was in direct contact with the support. After producing a metal-clad laminate using a three-layer polyimide film, the peel strength of the metal foil and the solder heat resistance were measured. The results are summarized in Table 1.

(Example 2)
Using a multi-manifold three-layer coextrusion three-layer die with a lip width of 200 mm, the polyamic acid solution obtained in Synthesis Example 3 / the polyamic acid solution obtained in Synthesis Example 1 / the polyamic acid solution obtained in Synthesis Example 3 Extruded and cast on an aluminum foil with a three-layer structure in the order of Then, after heating this three-layer film at 150 ° C. × 100 seconds, the three-layer gel film having self-supporting properties is peeled off and fixed to a metal frame, 250 ° C. × 40 seconds, 300 ° C. × 60 seconds, 350 Drying and imidization at ℃ × 60 seconds, 370 ° C × 30 seconds, and the thickness of the thermoplastic polyimide layer / non-thermoplastic polyimide layer / thermoplastic polyimide layer is 2.7 μm / 12.6 μm / 2.7 μm. A film was obtained.
At this time, the polyamic acid solution obtained in Synthesis Example 3 is only acetic anhydride / isoquinoline with respect to 100 g of this polyamic acid solution just before the polyamic acid solution on the surface directly contacting the support is put into the three-layer die. 20 g of a curing agent consisting of / DMF (weight ratio 33.0 g / 8.3 g / 58.6 g) was added and mixed with a mixer.
After producing a metal-clad laminate using a three-layer polyimide film, the peel strength of the metal foil and the solder heat resistance were measured. The results are summarized in Table 1.

(Comparative Example 2)
The same procedure as in Example 1 was conducted except that the chemical dehydrating agent and the imidization catalyst were not added to the polyamic acid solution of Synthesis Example 3. After producing a metal-clad laminate using a three-layer polyimide film, the peel strength of the metal foil and the solder heat resistance were measured. The results are summarized in Table 1. There was a trace of peeling on the B-surface thermoplastic polyimide layer that was in direct contact with the support.

Claims (6)

  A multilayer polyimide in which a plurality of polyamic acid solutions are cast on a support by multilayer coextrusion, and a thermoplastic polyimide layer containing at least a thermoplastic polyimide is laminated on at least one surface of a non-thermoplastic polyimide layer containing at least a non-thermoplastic polyimide. A method for producing a film, which comprises incorporating an imidization catalyst only in a polyamic acid solution in direct contact with a support.   The method for producing a multilayer coextruded polyimide film according to claim 1, wherein a chemical dehydrating agent and an imidization catalyst are contained only in the polyamic acid solution in direct contact with the support.   The method for producing a multilayer coextruded polyimide film according to claim 1 or 2, wherein the polyamic acid solution in direct contact with the support is a polyamic acid solution that becomes a thermoplastic polyimide layer.   60% or more of the total number of moles of the acid dianhydride monomer and diamine monomer constituting the thermoplastic polyimide is the acid dianhydride monomer and diamine monomer constituting the non-thermoplastic polyimide. The manufacturing method of the multilayer coextrusion polyimide film of any one of Claims 1-3 characterized by the above-mentioned.   The multilayer according to any one of claims 1 to 4, wherein the diamine constituting the thermoplastic polyimide contains 2,2-bis [4- (4-aminophenoxy) phenyl] propane as an essential component. A method for producing a coextruded polyimide film.   The polyamic acid which becomes the said non-thermoplastic polyimide layer is a polyamic acid which is a precursor of the non-thermoplastic polyimide which has a thermoplastic block component in a molecule | numerator, The any one of Claims 1-5 characterized by the above-mentioned. The manufacturing method of the multilayer coextruded polyimide film of description.