CN116133855A

CN116133855A - Multilayer polyimide film

Info

Publication number: CN116133855A
Application number: CN202180060432.XA
Authority: CN
Inventors: 秋永隆宏; 斋藤隼平
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 2020-07-17
Filing date: 2021-06-18
Publication date: 2023-05-16
Also published as: JPWO2022014257A1; TW202208513A; WO2022014257A1; KR20230038757A

Abstract

The multilayered polyimide film (10) has a non-thermoplastic polyimide layer (11) and a thermoplastic polyimide layer (12) disposed on at least one side of the non-thermoplastic polyimide layer (11). The non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer (11) has a tetracarboxylic dianhydride residue and a diamine residue. Diamine residues include diamine residues having a biphenyl backbone, 4' -diaminodiphenyl ether residues, and p-phenylenediamine residues. The content of the diamine residues having a biphenyl skeleton is 20 mol% or more and 35 mol% or less relative to the total diamine residues constituting the non-thermoplastic polyimide.

Description

Multilayer polyimide film

Technical Field

The present invention relates to a multilayer polyimide film.

Background

In recent years, as demands for electronic products such as smart phones, tablet computers, notebook computers, and the like have increased, demands for flexible printed circuit boards (hereinafter, sometimes referred to as "FPCs") have increased. Among them, a flexible printed circuit board using a multilayered polyimide film including a thermoplastic polyimide layer as an adhesive layer as a material is required to be further increased because of excellent heat resistance and bending property. In recent years, the electronic devices have been reduced in weight, size, and film thickness, and there has been a strong demand for miniaturization of FPC wiring.

In the production of a fine double-sided FPC or a multi-layer FPC, a metal-clad laminate obtained by bonding metal foils such as copper foil to both sides of a polyimide film is generally used as a material. In the manufacture of FPC, there is a step of first opening a hole (hereinafter, sometimes referred to as "through hole") for conducting interlayer connection. The inner wall of the through hole is plated to conduct both sides of the wiring board. In the via hole forming step, there are a via hole method in which a via hole is formed in a metal foil and an insulating layer (polyimide layer) on both sides by a drill or laser, and a blind hole method in which a metal foil and an insulating layer on one side are cut by a laser or the like and a metal foil on the other side is left, and in particular, in a fine FPC, a blind hole method is used at a high frequency in order to use an area effectively.

Conventionally, in such a through-hole forming step, in order to clean the inside of the hole and the surface of the metal foil after the hole is opened or remove the resin residue, a wet-type desmutting treatment has been performed in which the laminated plate is treated with an aqueous alkaline potassium permanganate solution or the like under heating. Polyimide is originally easily hydrolyzed under alkaline conditions, but when laser processing is performed, residual stress is generated by local heating, and thus defects such as cracks are easily generated in the inner wall of the through hole during the desmutting process after the through hole forming process. Patent document 1 describes a method of suppressing the occurrence of defects by performing a heat treatment step between laser processing and desmutting treatment to remove residual stress generated during laser processing. Patent document 2 discloses polyimide having resistance to an alkaline solution used in a developing step, an etching treatment step, and a resist stripping step.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2012-186377

Patent document 2: japanese patent application laid-open No. 2017-179148

Disclosure of Invention

Problems to be solved by the invention

Cracks generated in the inner wall of the through hole by desmear treatment after laser processing cause deformation of the plated portion and degradation of connection reliability, or cause degradation of insulation reliability due to penetration of chemical solution into the cracks in the process after plating treatment, thus adversely affecting quality. Cracks are more likely to occur when blind holes are formed than when through holes are formed. It is to be noted that, as a result of the study by the present inventors, it was found that: when the metal foil is removed by etching or the like without performing the desmutting treatment after the laser processing, or when the desmutting treatment is performed in a state where the metal foil is removed without performing the laser processing, no crack is generated. Further, as a result of studies by the present inventors, it was found that: in the desmutting treatment after laser processing, if the swelling time and the roughening time are prolonged, cracks are likely to occur.

As a method for suppressing the occurrence of cracks, if a method of adding a heat treatment step between laser processing and desmutting treatment disclosed in patent document 1 is adopted, the productivity of the circuit board is lowered due to the additional heat treatment step. In addition, the method described in patent document 1 has room for improvement in suppressing the occurrence of cracks in the inner wall of the through hole.

In addition, although the method described in patent document 2 can suppress the cracking of the thin film in an alkaline environment, there is room for improvement in suppressing the occurrence of cracks in the inner wall of the through hole.

The present invention has been made in view of these problems, and an object of the present invention is to provide a multilayer polyimide film capable of suppressing occurrence of cracks in the inner wall of a via hole during desmear treatment after laser processing.

Solution for solving the problem

In the desmear treatment after laser processing, it is important to alleviate stress generated in the polyimide film during laser processing in order to suppress the occurrence of cracks in the inner wall of the through hole. On the other hand, if a polyimide film containing a large amount of soft skeleton is used, the stress is easily relaxed, but such polyimide has a very large linear expansion coefficient compared with the bonded metal, and therefore warpage or wrinkles occur at the time of bonding with the metal foil. As a result of intensive studies, the present inventors have found that by using polyimide having a specific structure as a non-thermoplastic polyimide used as a core material for a multilayered polyimide film, it is possible to ensure a linear expansion coefficient equivalent to that of a metal and to alleviate stress generated in the polyimide film during laser processing.

The multilayer polyimide film of the present invention has a non-thermoplastic polyimide layer and a thermoplastic polyimide layer disposed on at least one side of the non-thermoplastic polyimide layer. The non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer has a tetracarboxylic dianhydride residue and a diamine residue. The diamine residues include diamine residues having a biphenyl backbone, 4' -diaminodiphenyl ether residues, and p-phenylenediamine residues. The content of the diamine residues having a biphenyl skeleton is 20 mol% or more and 35 mol% or less with respect to all diamine residues constituting the non-thermoplastic polyimide.

In the multilayer polyimide film according to an embodiment of the present invention, the diamine residue having a biphenyl skeleton is a 4,4 '-diamino-2, 2' -dimethylbiphenyl residue.

In the multilayer polyimide film according to one embodiment of the present invention, the content of the 4,4' -diaminodiphenyl ether residue is 40 mol% or more and 70 mol% or less with respect to all diamine residues constituting the non-thermoplastic polyimide.

In the multilayer polyimide film according to one embodiment of the present invention, the content of the p-phenylenediamine residue is 5 mol% or more and 50 mol% or less with respect to all diamine residues constituting the non-thermoplastic polyimide.

In the multilayer polyimide film according to an embodiment of the present invention, the tetracarboxylic dianhydride residue includes one or more selected from the group consisting of 3,3', 4' -biphenyl tetracarboxylic dianhydride residues and pyromellitic dianhydride residues.

In the multilayer polyimide film of one embodiment of the present invention, the tetracarboxylic dianhydride residue further comprises a 4,4' -oxydiphthalic anhydride residue.

In the multilayer polyimide film according to one embodiment of the present invention, the content of the 4,4' -oxydiphthalic anhydride residues is 5 mol% or more and 15 mol% or less with respect to all tetracarboxylic dianhydride residues constituting the non-thermoplastic polyimide.

In the multilayer polyimide film according to an embodiment of the present invention, the thermoplastic polyimide contained in the thermoplastic polyimide layer has one or more selected from the group consisting of 3,3', 4' -biphenyltetracarboxylic dianhydride residues and pyromellitic dianhydride residues and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane residues.

In one embodiment of the multilayer polyimide film of the present invention, the non-thermoplastic polyimide layer has a storage modulus of less than 0.350GPa at a temperature of 380 ℃.

In the multilayer polyimide film according to one embodiment of the present invention, the non-thermoplastic polyimide layer has a linear expansion coefficient of 5.0ppm/K or more and 19.0ppm/K or less at a temperature of 100 ℃ to 200 ℃.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the multilayer polyimide film of the present invention, the occurrence of cracks in the inner wall of the through-hole can be suppressed during desmear treatment after laser processing without increasing man-hours in the manufacturing process of the circuit board.

Drawings

FIG. 1 is a cross-sectional view showing an example of a multilayer polyimide film of the present invention.

FIG. 2 is a cross-sectional view showing a metal-clad laminate obtained by using an example of the multilayer polyimide film of the present invention.

Fig. 3 is an example of a polarized light microscope image used in the judgment of the hole crack test.

Fig. 4 is another example of a polarized light microscope image used in the judgment of the hole crack test.

Fig. 5 is another example of a polarized light microscope image used in the judgment of the hole crack test.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited thereto. The entire academic literature and patent literature described in the present specification are incorporated by reference into the present specification.

First, terms used in the present specification will be described. "polyimide" is a polymer having a structural unit represented by the following general formula (1) as a repeating unit.

In the general formula (1), X represents a tetracarboxylic dianhydride residue (a 4-valent organic group derived from tetracarboxylic dianhydride), and Y represents a diamine residue (a 2-valent organic group derived from diamine).

The "biphenyl skeleton" refers to a skeleton of a 2-ring structure in which 2 benzene rings are bonded by 1 single bond. Therefore, the diamine residue having a biphenyl skeleton does not include a diamine residue having a condensed ring such as a 9, 9-bis (4-aminophenyl) fluorene residue.

The "linear expansion coefficient" is a linear expansion coefficient at a temperature of 100℃to 200℃when the temperature is raised, unless otherwise specified.

The term "non-thermoplastic polyimide" refers to a polyimide which is fixed in a thin film state to a metal fixing frame and which retains a thin film shape (flat film shape) without generating wrinkles or elongation when heated at a heating temperature of 450 ℃ for 2 minutes. The "thermoplastic polyimide" is a polyimide which is fixed in a film state to a metal fixing frame and is not kept in a film shape when heated at a heating temperature of 450 ℃ for 2 minutes.

The "main surface" of the laminate (more specifically, the non-thermoplastic polyimide layer, etc.) refers to a surface orthogonal to the thickness direction of the laminate.

Hereinafter, a compound and its derivatives may be collectively referred to by the term "system" followed by the name of the compound.

< multilayer polyimide film >

The multilayered polyimide film according to the present embodiment includes a non-thermoplastic polyimide layer and a thermoplastic polyimide layer disposed on at least one side (one main surface) of the non-thermoplastic polyimide layer. The non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer has tetracarboxylic dianhydride residues and diamine residues. Diamine residues include diamine residues having a biphenyl skeleton (residues derived from diamines having a biphenyl skeleton), 4' -diaminodiphenyl ether residues, and p-phenylenediamine residues. The content of the diamine residue having a biphenyl skeleton is preferably 20 mol% or more and 35 mol% or less with respect to the total diamine residues constituting the non-thermoplastic polyimide.

Hereinafter, the tetracarboxylic dianhydride may be referred to as "acid dianhydride". Diamines having a biphenyl skeleton are sometimes described as "BPDI". 4,4' -diaminodiphenyl ether is sometimes described as "ODA". P-phenylenediamine is sometimes referred to as a "PDA". In addition, the non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer may be referred to as "non-thermoplastic polyimide" only. The thermoplastic polyimide contained in the thermoplastic polyimide layer is sometimes referred to as "thermoplastic polyimide" only.

The present inventors have conducted intensive studies on molecular design of polyimide capable of relaxing stress generated in a thin film at the time of laser processing while maintaining heat resistance (linear expansion coefficient, etc.) at the time of use in a metal clad laminate. As a result, the present inventors found that: by optimizing the structure of the non-thermoplastic polyimide contained in the multilayered polyimide film, the occurrence of cracks in the inner wall of the via hole can be suppressed at the time of desmutting treatment after laser processing without applying a large change to the manufacturing process of the circuit board.

[ constitution of multilayer polyimide film ]

The structure of the multilayered polyimide film according to the present embodiment will be described below with reference to the drawings. For ease of understanding, the main body of the drawing to be referred to schematically shows the respective components, and for ease of manufacturing the drawing, the size, number, shape, etc. of the respective components shown in the drawing may be different from the actual ones. In the present specification, for convenience of description, the same reference numerals are given to the same components as those in the drawings described above, and the description thereof may be omitted.

FIG. 1 is a cross-sectional view showing an example of a multilayer polyimide film of the present invention. As shown in fig. 1, the multilayered polyimide film 10 has a non-thermoplastic polyimide layer 11 and a thermoplastic polyimide layer 12 disposed on at least one side of the non-thermoplastic polyimide layer 11. The non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer 11 has a tetracarboxylic dianhydride residue and a diamine residue. Diamine residues include BPDI residues, ODA residues and PDA residues. The content of BPDI residues is preferably 20 mol% or more and 35 mol% or less with respect to all diamine residues constituting the non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer 11.

With the multilayer polyimide film 10, occurrence of cracks in the inner wall of the through hole can be suppressed at the time of desmutting treatment after laser processing. The reason is presumed to be as follows. In the multilayer polyimide film 10, the non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer 11 has BPDI residues having a skeleton with a high degree of free rotation of molecular chains at a content within a specific range. Further, the non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer 11 has ODA residues of a curved structure contributing to the flexibility of the multilayer polyimide film 10 and PDA residues of a rigid structure contributing to the heat resistance of the multilayer polyimide film 10. Thus, the multilayer polyimide film 10 can alleviate stress generated in the film during laser processing while maintaining heat resistance (linear expansion coefficient, etc.) when used for a metal clad laminate. Therefore, with the multilayer polyimide film 10, the occurrence of cracks in the inner wall of the through hole can be suppressed during desmear treatment after laser processing. In order to more effectively suppress the occurrence of cracks in the inner wall of the through hole, the benzene ring in the BPDI residue preferably has a substituent, more preferably has an alkyl group, and further preferably has a methyl group. When the benzene ring in the BPDI residue has a substituent, the symmetry of the primary structure of polyimide is lowered, and thus the stacking (packing) of the polymer chain is hindered, and the stress generated in the thin film during laser processing is further relaxed.

In the multilayer polyimide film 10 shown in fig. 1, the thermoplastic polyimide layer 12 is provided only on one side of the non-thermoplastic polyimide layer 11, but the thermoplastic polyimide layer 12 may be provided on both sides (both principal surfaces) of the non-thermoplastic polyimide layer 11. When the thermoplastic polyimide layers 12 are provided on both sides of the non-thermoplastic polyimide layer 11, the two thermoplastic polyimide layers 12 may contain the same thermoplastic polyimide or different thermoplastic polyimides. The thickness of the two thermoplastic polyimide layers 12 may be the same or different. In the present invention, 2 or more layers may be provided for both the non-thermoplastic polyimide layer 11 and the thermoplastic polyimide layer 12. In the following description, the "multilayer polyimide film 10" includes a film having the thermoplastic polyimide layer 12 provided only on one side of the non-thermoplastic polyimide layer 11, a film having the thermoplastic polyimide layer 12 provided on both sides of the non-thermoplastic polyimide layer 11, and a film having 2 or more layers of both the non-thermoplastic polyimide layer 11 and the thermoplastic polyimide layer 12.

The thickness of the multilayered polyimide film 10 (total thickness of the layers) is, for example, 6 μm or more and 60 μm or less. The thinner the thickness of the multilayered polyimide film 10 is, the more easily the weight of the obtained FPC becomes, and the more the flexibility of the obtained FPC becomes. In order to make the weight reduction of the FPC easier while securing mechanical strength and to further improve the bending property of the FPC, the thickness of the multilayer polyimide film 10 is preferably 7 μm or more and 30 μm or less, more preferably 10 μm or more and 25 μm or less. The thickness of the multilayer polyimide film 10 can be measured using a Laser holographic micrometer (Laser Hologage).

In order to ensure adhesion to the metal foil and to facilitate thinning of the FPC, the thickness of the thermoplastic polyimide layer 12 (when the thermoplastic polyimide layer 12 is provided in an amount of 2 or more layers, the thickness of each thermoplastic polyimide layer 12) is preferably 1 μm or more and 15 μm or less. In order to facilitate adjustment of the linear expansion coefficient of the multilayer polyimide film 10, the thickness ratio of the non-thermoplastic polyimide layer 11 to the thermoplastic polyimide layer 12 (the thickness of the non-thermoplastic polyimide layer 11/the thickness of the thermoplastic polyimide layer 12) is preferably 55/45 or more and 95/5 or less. When a plurality of non-thermoplastic polyimide layers 11 and thermoplastic polyimide layers 12 are provided, respectively, the thickness ratio is a ratio of the respective total thicknesses. It is preferable that the total thickness of the thermoplastic polyimide layer 12 does not exceed the total thickness of the non-thermoplastic polyimide layer 11 even if the number of layers of the thermoplastic polyimide layer 12 becomes large.

In order to suppress warpage of the multilayer polyimide film 10, it is preferable to provide thermoplastic polyimide layers 12 on both sides of the non-thermoplastic polyimide layer 11, and it is more preferable to provide thermoplastic polyimide layers 12 containing the same thermoplastic polyimide on both sides of the non-thermoplastic polyimide layer 11. When the thermoplastic polyimide layers 12 are provided on both sides of the non-thermoplastic polyimide layer 11, it is preferable that the thickness of the two thermoplastic polyimide layers 12 be the same in order to suppress warpage of the multilayer polyimide film 10. Even if the thicknesses of the two thermoplastic polyimide layers 12 are different from each other, when the thickness of the thicker thermoplastic polyimide layer 12 is used as a reference, the warpage of the multilayer polyimide film 10 can be suppressed as long as the thickness of the other thermoplastic polyimide layer 12 is in the range of 40% or more and less than 100%.

In order to further suppress the occurrence of cracks in the inner wall of the through hole at the time of desmutting treatment after laser processing, the storage modulus of the non-thermoplastic polyimide layer 11 at a temperature of 380 ℃ is preferably less than 0.350GPa, more preferably less than 0.200GPa. In addition, from the viewpoint of improving the mechanical strength of the multilayer polyimide film 10 at high temperature, the storage modulus is preferably 0.010GPa or more, more preferably 0.050GPa or more. The storage modulus can be adjusted, for example, by changing the content of BPDI residues. The method for measuring the storage modulus is the same method as or based on the examples described later.

In the dynamic viscoelasticity measurement of the non-thermoplastic polyimide layer 11, the temperature indicated by the inflection point of the storage modulus is preferably in the range of 270 ℃ to 340 ℃ and more preferably in the range of 280 ℃ to 330 ℃ from the viewpoints of stress relaxation during laser processing and thermal stress relaxation during metal foil bonding by a lamination method. If the temperature indicated by the inflection point of the storage modulus is within this range, dimensional changes at a temperature (for example, 250 ℃) at which dimensional changes after heating of the flexible metal-clad laminate are evaluated can be suppressed. On the other hand, if the temperature indicated by the inflection point of the storage modulus is low, the stress generated in the multilayer polyimide film 10 upon cooling after laser processing becomes small.

The linear expansion coefficient of the non-thermoplastic polyimide layer 11 is preferably 5.0ppm/K or more and 19.0ppm/K or less, more preferably 8.0ppm/K or more and 15.0ppm/K or less, and still more preferably 9.0ppm/K or more and 12.0ppm/K or less. If the linear expansion coefficient of the non-thermoplastic polyimide layer 11 is 5.0ppm/K or more and 19.0ppm/K or less, the linear expansion coefficient of the multilayered polyimide film 10 can be adjusted to, for example, 14.0ppm/K or more and 22.0ppm/K or less close to the copper foil, and desirably can be adjusted to 16.0ppm/K or more and 20.0ppm/K or less closer to the copper foil. Thus, the stress generated in the multilayer polyimide film 10 during cooling after laser processing is reduced, and the occurrence of cracks in the inner wall of the through hole during desmutting treatment after laser processing can be further suppressed. The linear expansion coefficient can be adjusted by changing, for example, the content of a residue derived from a monomer having a rigid structure (more specifically, PDA residue or the like) and the content of a residue derived from a monomer having a curved structure (more specifically, ODA residue or the like). The method for measuring the linear expansion coefficient is the same as or based on the examples described later.

The slope of the plastic deformation region in the stress-strain curve of the non-thermoplastic polyimide layer 11 is preferably 2.0 or more. In the case where the non-thermoplastic polyimide layer 11 is difficult to plastically deform and has high yield strength, high durability against cracking in an alkaline environment is exhibited. The plastic deformation region refers to a region of strain after the yield point in the stress-strain curve in the tensile test of the polyimide film. The characteristic of "difficult to plastically deform" means that the stress is greatly increased in the plastic deformation region or that the stress required at the time of plastic deformation is large. The characteristic of "difficult to plastically deform" is, for example, an index of the slope of the plastic deformation region. For example, the slope of the plastic deformation region is the slope of the s-s curve in the plastic deformation region in the graph in which the vertical axis is "stress (unit: MPa)" and the horizontal axis is "strain (unit: mm)" for the result of measuring the tensile characteristics according to ASTM D882. The slope of the s-s curve in the plastic deformation region can be calculated by the following calculation formula. In the following formula, stress1 is a stress at 10% strain, stress2 is a fracture stress, stress1 is a 10% strain, and stress2 is a fracture strain.

Slope of s-s curve in plastic deformation region= (stress 2-stress 1)/(stress 2-stress 1)

The slope of the plastic deformation region of the non-thermoplastic polyimide layer 11 is preferably 2.0 or more, more preferably 2.2 or more, and still more preferably 2.5 or more. When the slope of the plastic deformation region is 2.0 or more, an aggregated structure having a high degree of polymer chain stacking is formed, and occurrence of cracking can be suppressed even in a continuous FPC processing step. The higher the slope of the plastic deformation region, the better, but in order to suppress occurrence of springback or the like, the slope of the plastic deformation region is preferably 4.5 or less, more preferably 4.0 or less.

When a metal-clad laminate is produced using the multilayer polyimide film 10, a metal foil 13 is bonded to at least one side of the multilayer polyimide film 10 (for example, the surface 12a of the thermoplastic polyimide layer 12 in the case of fig. 1). Thus, the metal-clad laminate 20 shown in fig. 2 can be obtained. The method of bonding the metal foil 13 to the surface 12a of the thermoplastic polyimide layer 12 is not particularly limited, and various known methods can be employed. For example, a continuous process method based on a hot roll lamination apparatus or a twin belt press (DBP) having more than one pair of metal rolls may be employed. The specific configuration of the means for performing the heat roll lamination is not particularly limited, and a protective material is preferably disposed between the pressing surface and the metal foil 13 in order to improve the appearance of the obtained multilayer polyimide film 10.

When the thermoplastic polyimide layer 12 is provided on both sides of the non-thermoplastic polyimide layer 11, a metal foil 13 is bonded to both sides of the multilayered polyimide film 10 to obtain a double-sided metal-clad laminate (not shown).

[ element of multilayer polyimide film ]

Next, elements (constituent elements) of the multilayer polyimide film of the present embodiment will be described in detail.

(non-thermoplastic polyimide layer)

The non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer has BPDI residues, ODA residues and PDA residues as diamine residues. In order to further suppress the occurrence of cracks in the inner wall of the via hole during desmear treatment after laser processing, the total content of BPDI residues, ODA residues and PDA residues is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, still more preferably 90 mol% or more, and may be 100 mol% or more, relative to all diamine residues constituting the non-thermoplastic polyimide.

Examples of the diamine (monomer) for forming a BPDI residue include 4,4 '-diamino-2, 2' -dimethylbiphenyl (hereinafter, sometimes described as "m-TB"), 4 '-diaminobiphenyl, 4' -diamino-3, 3 '-dimethylbiphenyl, 4' -diamino-2, 2 '-dimethoxybiphenyl, 4' -diamino-3, 3 '-dimethoxybiphenyl, 3',5,5 '-tetramethylbenzidine, 4' -bis (4-aminophenoxy) biphenyl, and the like. In the present embodiment, one or two or more diamines may be used as the diamine for forming the BPDI residue. In order to further suppress the occurrence of cracks in the inner wall of the via hole at the time of desmutting treatment after laser processing, m-TB is preferable as diamine (monomer) for forming BPDI residues. That is, as the BPDI residue, an m-TB residue is preferable.

In order to further suppress occurrence of cracks in the inner wall of the via hole during desmear treatment after laser processing while maintaining the linear expansion coefficient, the content of ODA residues is preferably 40 mol% or more and 70 mol% or less, more preferably 45 mol% or more and 65 mol% or less, and still more preferably 50 mol% or more and 65 mol% or less, relative to the total diamine residues constituting the non-thermoplastic polyimide. In order to maintain the linear expansion coefficient and further suppress the occurrence of cracks in the inner wall of the via hole during desmear treatment after laser processing, the content of PDA residues relative to all diamine residues constituting the non-thermoplastic polyimide is preferably 5 mol% or more and 50 mol% or less, more preferably 10 mol% or more and 40 mol% or less, still more preferably 15 mol% or more and 30 mol% or less.

The non-thermoplastic polyimide may have a diamine residue other than a BPDI residue, an ODA residue, or a PDA residue (other diamine residue) as a diamine residue. As the diamine (monomer) for forming other diamine residues, aromatic diamines having high heat resistance are preferable. As specific examples of diamines used to form other diamine residues, examples thereof include 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 4' -diaminodiphenylpropane, 4' -diaminodiphenylmethane 4,4' -diaminodiphenyl sulfide, 3' -diaminodiphenyl sulfone, 4' -diaminodiphenyl sulfone, 3' -diaminodiphenyl ether 3,4' -diaminodiphenyl ether, 1, 5-diaminonaphthalene, 4' -diaminodiphenyl diethyl silane, 4' -diaminodiphenyl ethyl phosphine oxide, 4' -diaminodiphenyl N-methylamine, 4' -diaminodiphenyl N-aniline, 1, 3-diaminobenzene, 1, 2-diaminobenzene, and the like.

The non-thermoplastic polyimide has acid dianhydride residues in addition to diamine residues. As the acid dianhydride (monomer) for forming the acid dianhydride residue, aromatic acid dianhydride is preferable from the viewpoint of improving heat resistance. In addition, in order to further suppress the occurrence of cracks in the inner wall of the through hole at the time of desmutting treatment after laser processing, an acid dianhydride (monomer) having a biphenyl skeleton is preferable as an acid dianhydride (monomer) for forming an acid dianhydride residue. Specific examples of the acid dianhydride (monomer) used for forming the acid dianhydride residue include pyromellitic dianhydride (hereinafter, sometimes referred to as "PMDA"), 3', 4' -biphenyl tetracarboxylic dianhydride (hereinafter, sometimes referred to as "BPDA"), 2,3,6, 7-naphthalene tetracarboxylic dianhydride, 1,2,5, 6-naphthalene tetracarboxylic dianhydride, 2', 3' -biphenyl tetracarboxylic dianhydride, 3', 4' -benzophenone tetracarboxylic dianhydride (hereinafter, sometimes referred to as "BTDA"), 2', 3' -benzophenone tetracarboxylic dianhydride, 4 '-oxydiphthalic anhydride (hereinafter, sometimes referred to as "ODPA"), 3,4' -oxybisphthalic anhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 3,4,9, 10-perylene tetracarboxylic dianhydride, bis (3, 4-dicarboxyphenyl) propane dianhydride, 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, 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), derivatives thereof, and the like.

From the viewpoint of maintaining the linear expansion coefficient, the acid dianhydride residue is preferably at least one selected from the group consisting of BPDA residues and PMDA residues. In addition, in order to further suppress the occurrence of cracks in the inner wall of the through hole during desmutting treatment after laser processing, a BPDA residue having a biphenyl skeleton is preferable as the acid dianhydride residue. In the case where the non-thermoplastic polyimide contains a BPDA residue, the content of the BPDA residue relative to the total acid dianhydride residues constituting the non-thermoplastic polyimide is preferably 10 mol% or more and 60 mol% or less, more preferably 20 mol% or more and 60 mol% or less, and still more preferably 30 mol% or more and 60 mol% or less, in order to maintain the linear expansion coefficient and further suppress the occurrence of cracks in the inner wall of the through hole during desmutting treatment after laser processing. When the non-thermoplastic polyimide contains PMDA residues, the content of PMDA residues relative to the total acid dianhydride residues constituting the non-thermoplastic polyimide is preferably 40 mol% or more and 80 mol% or less, more preferably 40 mol% or more and 75 mol% or less, and still more preferably 40 mol% or more and 70 mol% or less, from the viewpoint of maintaining the linear expansion coefficient. In the case where the non-thermoplastic polyimide contains a BPDA residue and a PMDA residue, the total content of the BPDA residue and the PMDA residue is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and may be 100 mol% or more, based on the total acid dianhydride residues constituting the non-thermoplastic polyimide, in order to further suppress occurrence of cracks in the inner wall of the via hole during desmutting treatment after laser processing while maintaining the linear expansion coefficient.

In order to further suppress the occurrence of cracks in the inner wall of the via hole at the time of desmutting treatment after laser processing, the non-thermoplastic polyimide preferably has one or more selected from the group consisting of BPDA residues and PMDA residues, and ODPA residues as acid dianhydride residues. In the case where the non-thermoplastic polyimide contains ODPA residues, the content of ODPA residues with respect to the total acid dianhydride residues constituting the non-thermoplastic polyimide is preferably 5 mol% or more and 15 mol% or less in order to further suppress occurrence of cracks in the inner wall of the via hole during desmear treatment after laser processing. In the case where the non-thermoplastic polyimide contains at least one selected from the group consisting of a BPDA residue and a PMDA residue, and an ODPA residue, the total content of the BPDA residue, PMDA residue and ODPA residue is preferably 80 mol% or more, more preferably 90 mol% or more, or may be 100 mol% relative to the total acid dianhydride residues constituting the non-thermoplastic polyimide, in order to further suppress occurrence of cracks in the inner wall of the via hole during desmear treatment after laser processing while maintaining the linear expansion coefficient.

In order to maintain the appearance of the surface of the metal-clad laminate satisfactorily and to further suppress the occurrence of cracks in the inner wall of the through hole during desmear treatment after laser processing, the non-thermoplastic polyimide preferably has a segment having a structural unit represented by the following chemical formula (2) as a repeating unit. In the present specification, the term "segment" means a polymer chain formed of the same repeating unit constituting the block copolymer. In the present specification, the term "block copolymer" includes any of a pure block copolymer, a random block copolymer, and a copolymer having a tapered block (taper block) structure.

The segment (hereinafter, sometimes referred to as "specific segment") in which the structural unit represented by the formula (2) is a repeating unit can be formed by, for example, sequential polymerization described below.

The non-thermoplastic polyimide layer may contain components (additives) other than the non-thermoplastic polyimide. As the additive, for example, a dye, a surfactant, a leveling agent, a plasticizer, a silicone, a filler, a sensitizer, or the like can be used. The content of the non-thermoplastic polyimide in the non-thermoplastic polyimide layer is, for example, 70 wt% or more, preferably 80 wt% or more, more preferably 90 wt% or more, and may be 100 wt% or more, based on the total amount of the non-thermoplastic polyimide layer.

(thermoplastic polyimide layer)

The thermoplastic polyimide contained in the thermoplastic polyimide layer has an acid dianhydride residue and a diamine residue. As the acid dianhydride (monomer) for forming the acid dianhydride residue in the thermoplastic polyimide, the same compounds as those described above for forming the acid dianhydride residue in the non-thermoplastic polyimide can be mentioned. The acid dianhydride residue of the thermoplastic polyimide may be the same type as the acid dianhydride residue of the non-thermoplastic polyimide, or may be different types from each other.

In order to secure thermoplasticity, a diamine residue having a curved structure is preferable as a diamine residue of the thermoplastic polyimide. In order to ensure the thermoplasticity more easily, the content of the diamine residue having a curved structure is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and may be 100 mol% or more, based on the total diamine residues constituting the thermoplastic polyimide. Examples of the diamine (monomer) used for forming the diamine residue having a curved structure include 4,4 '-bis (4-aminophenoxy) biphenyl, 4' -bis (3-aminophenoxy) biphenyl, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 2-bis [4- (4-aminophenoxy) phenyl ] propane (hereinafter, sometimes referred to as "BAPP"), and the like. In order to ensure the thermoplasticity more easily, the diamine residue of the thermoplastic polyimide is preferably a BAPP residue.

In order to obtain a thermoplastic polyimide layer excellent in adhesion to a metal foil, it is preferable that the thermoplastic polyimide has at least one selected from the group consisting of BPDA residues and PMDA residues and BAPP residues.

The thermoplastic polyimide layer may contain a component (additive) other than the thermoplastic polyimide. As the additive, for example, a dye, a surfactant, a leveling agent, a plasticizer, a silicone, a filler, a sensitizer, or the like can be used. The content of the thermoplastic polyimide in the thermoplastic polyimide layer is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and may be 100% by weight or more, based on the total amount of the thermoplastic polyimide layer.

In order to particularly suppress occurrence of cracks in the inner wall of the through hole during desmutting treatment after laser processing, the multilayer polyimide film of the present embodiment preferably satisfies the following condition 1, more preferably satisfies the following condition 2, still more preferably satisfies the following condition 3, still more preferably satisfies the following condition 4, and particularly preferably satisfies the following condition 5.

Condition 1: the non-thermoplastic polyimide has m-TB residues, ODA residues, PDA residues, BPDA residues, and PMDA residues.

Condition 2: the above condition 1 is satisfied, and the content of ODA residues with respect to all diamine residues constituting the non-thermoplastic polyimide is 40 mol% or more and 70 mol% or less.

Condition 3: the PDA residues are contained in an amount of 5 to 50 mol% based on the total diamine residues constituting the non-thermoplastic polyimide, while satisfying the condition 2.

Condition 4: the above condition 3 is satisfied, and the non-thermoplastic polyimide is a block copolymer having a specific segment.

Condition 5: the above condition 4 is satisfied, and the non-thermoplastic polyimide further has an ODPA residue.

< method for producing multilayer polyimide film and method for producing Metal-clad laminate >

Next, an example of a method for producing a multilayer polyimide film according to the present embodiment and an example of a method for producing a metal-clad laminate using the multilayer polyimide film according to the present embodiment will be described.

[ method for producing multilayer polyimide film ]

(method for producing Polyamic acid)

As a method for producing a polyamic acid (synthesis method) which is a precursor of polyimide, all known methods and a method of combining them can be used. The polymerization method in the production of polyamide acid is characterized in that the addition order of the monomers is controlled, and the physical properties of the obtained polyimide can be controlled by controlling the addition order of the monomers. In the case of synthesizing a polyamic acid using a diamine and a tetracarboxylic dianhydride, a desired polyamic acid (a polymer of a diamine and a tetracarboxylic dianhydride) can be obtained by adjusting the amount of each diamine and the amount of each tetracarboxylic dianhydride (in the case of using a plurality of tetracarboxylic dianhydrides, the amount of each tetracarboxylic dianhydride). The ratio (molar ratio) of the amounts of substances of the respective residues in the polyimide formed from the polyamic acid is, for example, the same as the ratio of the amounts of substances of the respective monomers (diamine and tetracarboxylic dianhydride) used in the synthesis of the polyamic acid. The temperature conditions for the reaction of the diamine and the tetracarboxylic dianhydride, that is, the synthesis reaction of the polyamic acid are not particularly limited, and are, for example, in the range of 20℃to 150 ℃. The reaction time of the synthesis reaction of the polyamic acid is, for example, in the range of 10 minutes to 30 hours. In the present embodiment, any method of adding a monomer may be used for producing the polyamic acid. As a typical method for producing polyamide acid, the following method can be mentioned.

Examples of the method for producing the polyamic acid include a method in which polymerization is performed in the following steps (a-a) and (a-b) (hereinafter, sometimes referred to as "a polymerization method").

(A-a): a step of reacting an aromatic diamine with an aromatic acid dianhydride in an organic solvent in a state where the aromatic diamine is excessive, to obtain a prepolymer having amino groups at both terminals

(A-b): and (c) adding an aromatic diamine having a structure different from that used in the step (a-a), and further adding an aromatic acid dianhydride having a structure different from that used in the step (a-a), and polymerizing the aromatic diamine and the aromatic acid dianhydride so that the aromatic diamine and the aromatic acid dianhydride are substantially equimolar in all the steps.

The method for producing the polyamic acid may be a method in which polymerization is performed in the following steps (B-a) and (B-B) (hereinafter, this method may be referred to as "B polymerization method").

(B-a): a step of reacting an aromatic diamine with an aromatic acid dianhydride in an organic solvent in a state where the aromatic acid dianhydride is excessive, to obtain a prepolymer having acid anhydride groups at both terminals

(B-B): adding an aromatic acid dianhydride having a structure different from that used in the step (B-a), and further adding an aromatic diamine having a structure different from that used in the step (B-a), and polymerizing the aromatic diamine so that the aromatic diamine and the aromatic acid dianhydride in all the steps are substantially equimolar to each other

The synthetic method (e.g., the above-described a polymerization method, B polymerization method, etc.) in which the order of addition is set so that a specific diamine or specific acid dianhydride selectively reacts with any or specific diamine, any or specific acid dianhydride is referred to herein as sequential polymerization. Among the polymers obtained by sequential polymerization, polymers having 2 kinds of segments are referred to as diblock copolymers, and polymers having 3 kinds of segments are referred to as triblock copolymers. In contrast, in the present specification, a polymerization method (a polymerization method in which monomers arbitrarily react with each other) in which the order of addition of diamine and acid dianhydride is not set is referred to as random polymerization. The polymer obtained by random polymerization is referred to as a random copolymer.

In the present embodiment, sequential polymerization is preferable as a polymerization method for obtaining polyimide which effectively suppresses cracking of the film while maintaining the characteristics of the flexible metal-clad laminate.

The weight average molecular weight of the polyamic acid obtained by the above polymerization method is preferably in the range of 10,000 to 1,000,000, more preferably in the range of 20,000 to 500,000, and still more preferably in the range of 30,000 to 200,000. If the weight average molecular weight is 10,000 or more, the polyamic acid can be easily formed into a coating film. On the other hand, when the weight average molecular weight is 1,000,000 or less, the solvent is sufficiently soluble, and therefore a coating film having a smooth surface and a uniform thickness can be obtained by using a polyamic acid solution described later. The weight average molecular weight as used herein refers to a polyethylene oxide equivalent measured using Gel Permeation Chromatography (GPC).

In order to obtain polyimide, a method of obtaining polyimide from a polyamic acid solution containing a polyamic acid and an organic solvent may be used. Examples of the organic solvent that can be used for the polyamic acid solution include urea solvents such as tetramethylurea and N, N-dimethylethylurea; sulfoxide solvents such as dimethyl sulfoxide; sulfone solvents such as diphenyl sulfone and tetramethyl sulfone; amide solvents such as N, N-dimethylacetamide, N-dimethylformamide (hereinafter, sometimes referred to as "DMF"), N-diethylacetamide, N-methyl-2-pyrrolidone, and hexamethylphosphoric triamide; ester solvents such as gamma-butyrolactone; halogenated alkyl solvents such as chloroform and methylene chloride; aromatic hydrocarbon solvents such as benzene and toluene; phenolic solvents such as phenol and cresol; ketone solvents such as cyclopentanone; ether solvents such as tetrahydrofuran, 1, 3-dioxolane, 1, 4-dioxane, dimethyl ether, diethyl ether, diethylene glycol dimethyl ether, and p-cresol methyl ether. These solvents are usually used alone, but 2 or more kinds may be used in combination as appropriate. When the polyamic acid is obtained by the above polymerization method, the reaction solution (the solution after the reaction) itself may be used as the polyamic acid solution for obtaining polyimide. At this time, the organic solvent in the polyamic acid solution is the organic solvent used for the reaction in the above-described polymerization method. In addition, a polyamic acid solution may be prepared by dissolving a solid polyamic acid obtained by removing a solvent from a reaction solution in an organic solvent.

Additives such as dyes, surfactants, leveling agents, plasticizers, organic silicon, sensitizers and the like can be added to the polyamic acid solution. In addition, a filler may be added to the polyamic acid solution for the purpose of improving the properties of the film such as slidability, thermal conductivity, electric conductivity, corona resistance, and ring stiffness. As the filler, any filler may be used, and preferable examples thereof include fillers including silica, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, and the like.

The concentration of the polyamic acid in the polyamic acid solution is not particularly limited, and is, for example, 5% by weight to 35% by weight, preferably 8% by weight to 30% by weight, based on the total amount of the polyamic acid solution. When the concentration of the polyamide acid is 5% by weight or more and 35% by weight or less, an appropriate molecular weight and solution viscosity can be obtained.

(method for Forming non-thermoplastic polyimide layer)

The method for forming the non-thermoplastic polyimide layer is not particularly limited, and various known methods can be applied, and examples thereof include a method for forming a non-thermoplastic polyimide layer (polyimide film) through the following steps i) to iv).

Step i): and a step of reacting an aromatic diamine with an aromatic tetracarboxylic dianhydride in an organic solvent to obtain a polyamic acid solution containing a precursor of a non-thermoplastic polyimide (hereinafter, sometimes referred to as "non-thermoplastic polyamic acid solution").

Procedure ii): a step of forming a coating film by coating a support with a doping liquid containing the non-thermoplastic polyamic acid solution;

step iii): a step of heating the coating film on a support to form a self-supporting polyamic acid film (hereinafter, sometimes referred to as "gel film") and then peeling the gel film from the support

Step iv) heating the gel film to imidize the polyamic acid in the gel film, and drying the gel film to obtain a polyimide film containing a non-thermoplastic polyimide (a polyimide film that is a non-thermoplastic polyimide layer in a multilayered polyimide film).

In step ii), the method of applying the dopant solution to the support is not particularly limited, and a method using a conventionally known applicator such as a die coater, a comma coater (registered trademark), a reverse coater, or a blade coater may be used.

In the steps subsequent to step ii), the thermal imidization method and the chemical imidization method are roughly classified. The thermal imidization method is a method of imidizing a polyamide acid solution by applying the polyamide acid solution as a doping solution to a support and heating the same without using a dehydrated ring-closing agent or the like. Another chemical imidization method is a method of accelerating imidization by using a solution obtained by adding at least one of a dehydration ring-closing agent and a catalyst to a polyamic acid solution as an imidization accelerator as a doping solution. Although either method may be used, the productivity of the chemical imidization method is better.

As the dehydration ring-closing agent, an acid anhydride typified by acetic anhydride is suitably used. As the catalyst, tertiary amines such as aliphatic tertiary amines, aromatic tertiary amines and heterocyclic tertiary amines are suitably used.

As the support to which the dope is applied in step ii), a glass plate, an aluminum foil, an endless stainless steel belt, a stainless steel drum, or the like is suitably used. In step iii), heating conditions are set according to the thickness and production speed of the finally obtained film, and at least one of partial imidization and drying is performed, and then the polyamic acid film (gel film) is peeled off from the support.

Next, in step iv), the end portion of the gel film is fixed, and heat treatment is performed while avoiding shrinkage at the time of curing, whereby water, a residual solvent, an imidization accelerator, and the like are removed from the gel film, and the residual polyamic acid is completely imidized, to obtain a polyimide film containing a non-thermoplastic polyimide. The heating conditions may be appropriately set according to the thickness and production speed of the finally obtained film.

(method for Forming thermoplastic polyimide layer)

The thermoplastic polyimide layer can be obtained, for example, by applying a polyamic acid solution containing a polyamic acid that is a precursor of a thermoplastic polyimide (hereinafter, may be referred to as a "thermoplastic polyamic acid solution") to at least one side of a polyimide film (non-thermoplastic polyimide layer) obtained by using the non-thermoplastic polyamic acid solution, and then performing the same procedure as in the method for forming the non-thermoplastic polyimide layer (polyimide film). By this method, a multilayered polyimide film having a non-thermoplastic polyimide layer and a thermoplastic polyimide layer disposed on at least one side of the non-thermoplastic polyimide layer can be obtained. Alternatively, a solution containing a thermoplastic polyimide (thermoplastic polyimide solution) may be used instead of the thermoplastic polyamic acid solution, and a coating film made of the thermoplastic polyimide solution may be formed on at least one surface of the non-thermoplastic polyimide layer, and the coating film may be dried to form a thermoplastic polyimide layer.

For example, a coextrusion die may be used to form a laminate including a layer containing a polyamic acid that is a precursor of a non-thermoplastic polyimide and a layer containing a polyamic acid that is a precursor of a thermoplastic polyimide, and then the resulting laminate may be heated to form a non-thermoplastic polyimide layer and a thermoplastic polyimide layer. In this method, a metal-clad laminate (a laminate of a multilayered polyimide film and a metal foil) is obtained at the same time as imidization is completed by using a metal foil as a support. In the case of producing a multilayer polyimide film containing 3 or more polyimide layers, a method in which the above-described coating step and heating step are repeated a plurality of times, or a method in which a plurality of coating films are formed by coextrusion and continuous coating (continuous casting) and heated at one time is suitably used. The outermost surface of the multilayer polyimide film may be subjected to various surface treatments such as corona treatment and plasma treatment.

[ method for producing Metal-clad laminate ]

When a metal-clad laminate is produced using the multilayer polyimide film obtained by the above method, a metal foil is bonded to at least one side of the multilayer polyimide film as described above. The metal foil is not particularly limited, and any metal foil may be used. For example, a metal foil made of copper, stainless steel, nickel, aluminum, an alloy of these metals, or the like is suitably used. In general, a copper foil such as a rolled copper foil or an electrolytic copper foil is often used for a metal-clad laminate, and in this embodiment, a copper foil is also preferably used.

The metal foil may be subjected to surface treatment or the like according to the purpose, and the surface roughness or the like of the metal foil may be adjusted. Further, a rust preventive layer, a heat resistant layer, an adhesive layer, or the like may be formed on the surface of the metal foil. The thickness of the metal foil is not particularly limited as long as it can exert a sufficient function according to the application.

< processing of Metal-clad laminate >

When forming a through hole by laser processing using a metal clad laminate as a material, a laser beam is irradiated to a portion to be processed, whereby the metal clad laminate can be cut and perforated. The blind hole can be formed by penetrating the metal-clad laminate to form a through hole, or by removing only a polyimide layer exposed after removing a part of the metal foil on the upper surface. When forming the blind hole, the metal foil on the upper surface is removed by laser, and then the polyimide layer is removed by reducing the output of the laser, thereby stably forming the blind hole.

As the laser, a known type can be used. Short wavelength lasers such as UV-YAG laser and excimer laser are preferable because they exhibit very high absorptivity to both resin and metal. In the formation of the through-hole, a method of directly drilling the through-hole with a drill is widely used. As a method of removing the dirt after the laser processing, a known method can be used, and examples thereof include a wet dirt removing method including a swelling step using an aqueous alkali solution and a solution containing an organic solvent, a roughening step using an aqueous alkali solution containing sodium permanganate, potassium permanganate, or the like, and a neutralization step.

In the case of a double-sided metal-clad laminate, the inner walls of the holes after the desmutting treatment are plated to conduct both sides of the metal-clad laminate. As an example of the plating method, a method of forming an electroless copper plating layer on the inner wall surface with palladium as a core after attaching palladium to the inner wall of the hole is given. In this case, the plating layer of a desired thickness may be formed by electroless copper plating alone, or may be formed by electrolytic copper plating after the electroless copper plating is thinned.

Examples

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

< method for measuring physical Properties and method for evaluating physical Properties)

First, storage modulus and linear expansion coefficient of a polyimide film, and evaluation methods (Kong Liewen test) of examples and comparative examples will be described.

[ storage modulus at 380 ℃ C ]

The dynamic viscoelasticity of the polyimide film was measured under an air atmosphere using a dynamic viscoelasticity measuring device (DM 6100, hitachi High-Tech Science Corporation), and the storage modulus at 380℃was read by plotting the correlation between the storage modulus and the measured temperature. The measurement conditions are as follows.

Width of sample (polyimide film): 9mm of

Spacing of sample holders (clamps): 20mm of

Measuring temperature range: 0-440 DEG C

Heating rate: 3 ℃/min

Strain amplitude: 10 μm

Measuring frequency: 1Hz, 5Hz, 10Hz

Minimum tension/compression force: 100mN

Tension/compression gain: 1.5

Initial value of force amplitude: 100mN

[ coefficient of Linear expansion ]

The polyimide film was heated from-10 to 400℃under a nitrogen atmosphere using a thermal analyzer (TMA/SS 6100, manufactured by Hitachi High-Tech Science Corporation), cooled to-10℃and further heated to 400℃again, and the linear expansion coefficient was determined from the strain amount at 100℃to 200℃at the 2 nd temperature increase. The measurement conditions are as follows.

Dimensions of the sample (polyimide film): width 3mm and length 10mm

Load: 3g (29.4 mN)

Heating rate: 10 ℃/min

[ Kong Liewen test ]

An electrolytic copper foil having a thickness of 12 μm was disposed on both sides of the multilayer polyimide films obtained in examples and comparative examples described later (3 EC-M3S-HTE, manufactured by Sanyo Metal mining Co., ltd.), and a protective film (Apical (registered trademark) 125NPI, manufactured by Kaneka Co., ltd., thickness: 125 μm) was further disposed on the outer surface of each electrolytic copper foil, and in this state, lamination was performed at a lamination temperature of 360℃under a lamination pressure of 265N/cm (27 kgf/cm) and a lamination speed of 1.0M/min, to obtain a flexible copper-clad laminate. Next, the obtained flexible copper-clad laminate was cut into a rectangular shape of 5.0 cm. Times.20.0 cm to obtain a sample for processing. Next, blind holes (10 x 100 long and 1mm apart) having a diameter of 75 μm were formed in the sample for processing under the laser processing conditions described in table 1 using a UV-YAG laser.

TABLE 1

Next, after the desmutting treatment was performed on the samples after laser processing under the conditions shown in table 2, copper foil was removed by etching, and samples for evaluation were obtained. The manufacturers of the chemical solutions used in the decontamination treatment were all rombin electronic materials corporation. In addition, a water washing step is performed between the swelling step and the roughening step, between the roughening step and the neutralization step, and after the neutralization step.

TABLE 2

Then, the obtained sample for evaluation was observed with a polarizing microscope at 200 times magnification under crossed nicols to determine the presence or absence of cracks. Specifically, the state in which light leakage occurred around the hole was determined as "crack occurred", and after 100 holes were observed, the ratio of the holes in which the crack occurred (crack occurrence ratio) was obtained as a percentage. Fig. 3 to 5 show an example of a polarized light microscope image for actual judgment. Fig. 3 shows an example of a hole portion in which no crack is generated due to no light leakage around the hole portion. Fig. 4 and 5 show examples of hole portions in which cracks are generated due to light leakage occurring around the hole portions. The hole section was observed with an electron microscope for a hole section where the light leakage was weak and the presence or absence of a crack could not be determined.

< preparation of Polyamide acid solution >

Hereinafter, a method for producing the solutions P1 to P12 as the non-thermoplastic polyamic acid solution and the solution P13 as the thermoplastic polyamic acid solution will be described. The preparation of the solutions P1 to P13 was carried out under a nitrogen atmosphere at a temperature of 20 ℃.

[ preparation of solution P1 ]

After placing 328.53g of DMF and 17.70g of ODA in a glass flask having a capacity of 2L, 18.01g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 4.00g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Subsequently, after adding 5.77g of m-TB to the flask while stirring the flask content, 2.21g of PDA was added, followed by adding 11.42g of PMDA, and the flask content was further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.89g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, giving solution P1 as a non-thermoplastic polyamic acid solution.

The polyimide obtained from the polyamic acid in the obtained solution P1 was confirmed to be non-thermoplastic by the method shown below. First, 32.5g of imidization accelerator formed of acetic anhydride/isoquinoline/DMF (weight ratio: 11.48/3.40/18.18) was added to 65g of solution P1 to prepare a dope. Then, the dope was defoamed while being stirred in an atmosphere having a temperature of 0 ℃ or lower, and then the dope was applied to an aluminum foil by using a comma coater to form a coating film. Then, the coated film was heated at 115℃for 100 seconds to obtain a self-supporting gel film. The gel film obtained was peeled off from the aluminum foil and fixed to a metal fixing frame, and heated at a heating temperature of 250℃for 15 seconds, followed by heating at a heating temperature of 350℃for 79 seconds, followed by drying and imidization to obtain a polyimide film having a thickness of 12.5. Mu.m. The obtained polyimide film was fixed to a metal fixing frame, and heated at a heating temperature of 450 ℃ for 2 minutes, so that the shape (film shape) of the polyimide film was maintained. Thus, the polyimide obtained from the polyamic acid in solution P1 is a non-thermoplastic polyimide. In the solutions P2 to P12 prepared by the following methods, the polyimide film obtained by the same method as the film formation method using the solution P1 was fixed to a metal fixing frame, and was heated at a heating temperature of 450 ℃ for 2 minutes, so that the shape (film shape) of the polyimide film was maintained. Thus, the polyimides obtained from the polyamic acids in solutions P2 to P12 are all non-thermoplastic polyimides.

[ preparation of solution P2 ]

After 328.55g of DMF and 16.32g of ODA were placed in a glass flask having a capacity of 2L, 17.98g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 2.67g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Subsequently, after adding 7.21g of m-TB to the flask while stirring the flask content, 2.20g of PDA was added, followed by 12.74g of PMDA, and the flask content was further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.89g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P2 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P3 ]

After 328.78g of DMF and 17.31g of ODA were placed in a glass flask having a capacity of 2L, 22.70g of BPDA was slowly added to the flask while stirring the flask contents. After visually confirming that BPDA dissolved, the flask contents were further stirred for 30 minutes. Subsequently, after adding 5.65g of m-TB to the flask while stirring the flask content, 2.16g of PDA was added, followed by adding 11.31g of PMDA, and the flask content was further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.87g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P3 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P4 ]

After 328.41g of DMF and 16.51g of ODA were placed in a glass flask having a capacity of 2L, 18.20g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 2.70g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Subsequently, after adding 5.83g of m-TB to the flask while stirring the flask content, 2.97g of PDA was added, followed by adding 12.89g of PMDA, and the flask content was further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.90g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P4 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P5 ]

After 328.29g of DMF, 5.90g of m-TB, 3.75g of PDA and 15.30g of ODA were placed in a glass flask having a capacity of 2L, 18.39g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 15.75g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.91g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P5 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P6 ]

After 328.57g of DMF and 17.64g of ODA were placed in a glass flask having a capacity of 2L, 13.95g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 4.20g of ODPA was slowly added to the flask while stirring the flask contents. After the ODPA was visually confirmed to be dissolved, 3.99g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Subsequently, after adding 5.75g of m-TB to the flask while stirring the flask contents, 2.20g of PDA was added, followed by adding 11.38g of PMDA, and the flask contents were further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.89g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P6 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P7 ]

After 328.81g of DMF and 15.94g of ODA were placed in a glass flask having a capacity of 2L, 17.57g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 2.60g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Subsequently, 9.86g of m-TB was added to the flask while stirring the flask content, 0.72g of PDA was added, and then 12.44g of PMDA was added, and the flask content was further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.87g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P7 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P8 ]

After a glass flask having a capacity of 2L was charged with 327.90g of DMF, 4.57g of m-TB, 5.43g of PDA and 14.36g of ODA, 16.88g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 17.83g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.94g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P8 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P9 ]

After 328.27g of DMF and 16.71g of ODA were placed in a glass flask having a capacity of 2L, 18.41g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 2.73g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Subsequently, after adding 4.43g of m-TB to the flask while stirring the flask content, 3.76g of PDA was added, followed by 13.05g of PMDA, and the flask content was further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.91g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P9 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P10 ]

After a glass flask having a capacity of 2L was charged with 328.91g of DMF, 5.27g of ODA and 16.20g of BAPP, 8.48g of BTDA was slowly added to the flask while stirring the flask contents. After the dissolution of BTDA was visually confirmed, 7.17g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Next, 7.11g of PDA was added to the flask while stirring the flask contents, followed by 14.92g of PMDA, and the flask contents were further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.86g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P10 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P11 ]

After 328.49g of DMF and 12.29g of ODA were placed in a glass flask having a capacity of 2L, 16.06g of BPDA was slowly added to the flask while stirring the flask contents. After visually confirming that BPDA dissolved, the flask contents were further stirred for 30 minutes. Subsequently, after adding 11.58g of m-TB to the flask while stirring the flask content, 2.21g of PDA was added, followed by 16.96g of PMDA, and the flask content was further stirred for 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.89g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P11 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P12 ]

Into a glass flask having a capacity of 2L, 329.58g of DMF, 7.86g of m-TB, 12.36g of ODA, and 8.61g of 9, 9-bis (4-aminophenyl) fluorene (hereinafter, sometimes referred to as "BAFL") were placed, and then 16.35g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 14.01g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 0.81g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 2500 poise at a temperature of 23 ℃, the addition of PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P12 as a non-thermoplastic polyamic acid solution.

[ preparation of solution P13 ]

After 673.24g of DMF and 71.83g of BAPP were placed in a glass flask having a capacity of 2L, 7.72g of BPDA was slowly added to the flask while stirring the flask contents. After the BPDA was visually confirmed to be dissolved, 31.30g of PMDA was slowly added to the flask while stirring the flask contents. After visual confirmation of PMDA dissolution, the flask contents were stirred for a further 30 minutes. Next, a PMDA solution prepared in advance (solvent: DMF, amount of PMDA dissolved: 1.15g, concentration of PMDA: 7.2 wt%) was added to the flask while stirring the flask contents. When the PMDA solution was added to the flask, the solution was slowly added so that the viscosity of the flask contents did not rise sharply. Then, when the viscosity of the flask contents reached 300 poise at the temperature of 23 ℃, the addition of the PMDA solution and the stirring of the flask contents were stopped, to obtain a solution P13 as a thermoplastic polyamic acid solution.

The polyimide obtained from the polyamic acid in the solution P13 was confirmed to be thermoplastic by the method shown below. First, 30.0g of an imidization accelerator formed of acetic anhydride/isoquinoline/DMF (weight ratio: 6.89/2.14/20.97) was added to 60g of solution P13 to prepare a dope. Then, the dope was defoamed while being stirred in an atmosphere having a temperature of 0 ℃ or lower, and then the dope was applied to an aluminum foil by using a comma coater to form a coating film. Then, the coated film was heated at a heating temperature of 120℃for 3 minutes to obtain a self-supporting gel film. The gel film obtained was peeled off from the aluminum foil and fixed on a metal fixing frame, and heated at a heating temperature of 250℃for 1 minute, followed by heating at a heating temperature of 300℃for 200 seconds, followed by drying and imidization, to obtain a polyimide film having a thickness of 20.0. Mu.m. The obtained polyimide film was fixed to a metal fixing frame, and heated at a heating temperature of 450 ℃ for 2 minutes, so that the shape (film shape) of the polyimide film was not maintained. Thus, the polyimide obtained from the polyamic acid in solution P13 is a thermoplastic polyimide.

< preparation of multilayer polyimide film >

Hereinafter, the method for producing the multilayer polyimide films of examples 1 to 7 and comparative examples 1 to 5 will be described.

Example 1

To 65g of solution P1 was added 32.5g of imidization accelerator formed by acetic anhydride/isoquinoline/DMF (weight ratio: 11.48/3.40/18.18), to prepare a dope. Then, the dope was defoamed while being stirred in an atmosphere having a temperature of 0 ℃ or lower, and then the dope was applied to an aluminum foil by using a comma coater to form a coating film. Then, the coated film was heated at 115℃for 100 seconds to obtain a self-supporting gel film. The gel film obtained was peeled off from the aluminum foil and fixed on a metal fixing frame, and heated at a heating temperature of 250℃for 15 seconds, followed by heating at a heating temperature of 350℃for 79 seconds, followed by drying and imidization, to obtain a polyimide film having a thickness of 12.5. Mu.m. Physical properties of the obtained polyimide film (non-thermoplastic polyimide layer) are shown in table 4. The "physical properties of the non-thermoplastic polyimide layer" in Table 4 are physical properties measured using a polyimide film having a thickness of 12.5. Mu.m.

Next, the solution P13 was diluted with DMF to a solid content concentration of 8 wt%, and a dope was prepared and applied to both sides of the polyimide film (the polyimide film obtained using the solution P1) to form a coating film. The coating amount at this time was adjusted so that the thickness of each thermoplastic polyimide layer (adhesive layer) formed became 3. Mu.m. Then, the coating film was heated at a heating temperature of 120℃for 2 minutes, and then heated at a heating temperature of 350℃for 15 seconds, followed by drying and imidization, to obtain a multilayer polyimide film of example 1. The results of the hole crack test (crack generation rate) of the obtained multilayer polyimide film are shown in table 4. The surface of the copper-clad laminate manufactured at the time of Kong Liewen test was free from wrinkles and the like, and was excellent in appearance.

Examples 2 to 7 and comparative examples 1 to 5

In the same manner as in example 1 except that the non-thermoplastic polyamic acid solution shown in Table 4 was used in place of the solution P1, the multilayer polyimide films of examples 2 to 7 and comparative examples 1 to 5 were obtained, respectively. In examples 2 to 7 and comparative examples 1 to 5, the amount of the non-thermoplastic polyamic acid solution used was 65g. The results of the hole crack test (crack generation rate) of the obtained multilayer polyimide film are shown in table 4. In examples 2 to 4, example 6, example 7 and comparative examples 2 to 4, the surfaces of the copper-clad laminates produced during the hole crack test were all free from wrinkles and the like, and a copper-clad laminate having a good appearance was obtained. On the other hand, with respect to example 5, comparative example 1 and comparative example 5, wrinkles were present in a part of the surface of the copper-clad laminate sheet produced at the time of hole crack test.

< evaluation result >

The materials used for each of the solutions P1 to P13 and the proportions thereof are shown in table 3. The ratio (molar ratio) of the amounts of substances of the respective residues in the polyimide obtained by using the solutions P1 to P13 was identical to the ratio of the amounts of substances of the respective monomers (diamine and tetracarboxylic dianhydride) used. In table 4, the types of the non-thermoplastic polyamic acid solutions used, the physical properties of the non-thermoplastic polyimide layer, and the results of the hole crack test (crack generation rate) are shown for example 1 to example 7 and comparative examples 1 to 5, respectively. In table 3, "-" means that the component was not used. In Table 3, the values in the column "acid dianhydride" are the content (unit: mol%) of each acid dianhydride relative to the total amount of the acid dianhydride used. The number in the column "diamine" is the content (unit: mol%) of each diamine relative to the total amount of diamine used.

TABLE 3

TABLE 4

In examples 1-7, the non-thermoplastic polyimide had an m-TB residue, an ODA residue, and a PDA residue as one of the BPDI residues. In examples 1 to 7, the content of m-TB residues was 20 mol% or more and 35 mol% or less based on the total diamine residues constituting the non-thermoplastic polyimide. In examples 1 to 7, the crack generation rate was 50% or less. The non-thermoplastic polyimide of examples 1 to 4, 6 and 7 was a block copolymer having a specific segment, but the non-thermoplastic polyimide of example 5 was a random copolymer.

In comparative examples 1 and 2, the content of BPDI residues (m-TB residues) was less than 20 mol% relative to the total diamine residues constituting the non-thermoplastic polyimide. In comparative example 3, the non-thermoplastic polyimide had no BPDI residues. In comparative example 4, the content of BPDI residues (m-TB residues) was more than 35 mol% based on the total diamine residues constituting the non-thermoplastic polyimide. In comparative example 5, the non-thermoplastic polyimide had no PDA residues. In comparative examples 1 to 5, the crack generation rate exceeded 50%.

From the above results, it was revealed that the multilayer polyimide film of the present invention was able to suppress the occurrence of cracks in the inner wall of the through hole during desmutting treatment after laser processing.

Description of the reference numerals

10: multilayer polyimide film

11: non-thermoplastic polyimide layer

12: thermoplastic polyimide layer

Claims

1. A multilayer polyimide film, wherein the multilayer polyimide film has a non-thermoplastic polyimide layer and a thermoplastic polyimide layer disposed on at least one side of the non-thermoplastic polyimide layer,

the non-thermoplastic polyimide contained in the non-thermoplastic polyimide layer has a tetracarboxylic dianhydride residue and a diamine residue,

the diamine residues include diamine residues having a biphenyl skeleton, 4' -diaminodiphenyl ether residues and p-phenylenediamine residues,

The content of the diamine residues having a biphenyl skeleton is 20 mol% or more and 35 mol% or less with respect to all diamine residues constituting the non-thermoplastic polyimide.

2. The multilayer polyimide film according to claim 1, wherein the diamine residue having a biphenyl skeleton is a 4,4 '-diamino-2, 2' -dimethylbiphenyl residue.

3. The multilayer polyimide film according to claim 1 or 2, wherein the content of the 4,4' -diaminodiphenyl ether residue is 40 mol% or more and 70 mol% or less with respect to all diamine residues constituting the non-thermoplastic polyimide.

4. The multilayer polyimide film according to any one of claims 1 to 3, wherein the content of the p-phenylenediamine residue is 5 mol% or more and 50 mol% or less with respect to all diamine residues constituting the non-thermoplastic polyimide.

5. The multilayer polyimide film according to any one of claims 1 to 4, wherein the tetracarboxylic dianhydride residue comprises one or more selected from the group consisting of 3,3', 4' -biphenyl tetracarboxylic dianhydride residues and pyromellitic dianhydride residues.

6. The multilayer polyimide film of claim 5, wherein the tetracarboxylic dianhydride residues further comprise 4,4' -oxydiphthalic anhydride residues.

7. The multilayer polyimide film according to claim 6, wherein the content of the 4,4' -oxydiphthalic anhydride residues is 5 mol% or more and 15 mol% or less relative to all tetracarboxylic dianhydride residues constituting the non-thermoplastic polyimide.

8. The multilayer polyimide film according to any one of claims 1 to 7, wherein the thermoplastic polyimide contained in the thermoplastic polyimide layer has one or more selected from the group consisting of 3,3', 4' -biphenyltetracarboxylic dianhydride residues and pyromellitic dianhydride residues and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane residues.

9. The multilayer polyimide film of any of claims 1 to 8, wherein the non-thermoplastic polyimide layer has a storage modulus of less than 0.350GPa at a temperature of 380 ℃.

10. The multilayer polyimide film according to any one of claims 1 to 9, wherein the non-thermoplastic polyimide layer has a linear expansion coefficient of 5.0ppm/K or more and 19.0ppm/K or less at a temperature rise at a temperature of 100 ℃ to 200 ℃.