JP7578408B2 - Polyimide, polyimide composition, adhesive film, laminate, coverlay film, resin-coated copper foil, metal-clad laminate, circuit board, and multilayer circuit board - Google Patents

Description

The present invention relates to polyimides useful as materials for electronic components, and polyimide compositions, adhesive films, laminates, coverlay films, resin-coated copper foils, metal-clad laminates, circuit boards, and multilayer circuit boards that use the polyimides.

In recent years, with the progress of miniaturization, weight saving, and space saving of electronic devices, there is an increasing demand for flexible printed circuits (FPCs) that are thin, lightweight, flexible, and have excellent durability even when repeatedly bent. Because FPCs allow three-dimensional and high-density mounting even in a limited space, their applications are expanding to include wiring for electronic devices such as HDDs, DVDs, and smartphones, as well as components such as cables and connectors.

In addition to higher density, the performance of devices has also improved, making it necessary to accommodate higher frequencies for transmitted signals. When transmitting high-frequency signals, if there is a large transmission loss in the transmission path, problems such as loss of electrical signals and longer signal delay times will occur. For this reason, it will be important to further reduce the transmission loss of high-frequency signals in FPCs in the future.

One type of FPC known is one in which a circuit pattern is formed on a polyimide film that has excellent heat resistance and flexibility, and a coverlay film having an adhesive layer is laminated to the surface. As the material for the adhesive layer of a coverlay film with such a structure, it has been proposed to use a polyimide made from a diamine derived from a dimer acid in which the two terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups (for example, Patent Document 1).

In addition, in a double-sided metal-clad laminate having a structure in which two single-sided metal-clad laminates are bonded together with an adhesive layer, it has been proposed to use a polyimide containing a predetermined amount or more of diamine residues derived from a diamine derived from a dimer acid in the adhesive layer (for example, Patent Document 2).

Patent No. 6488170 JP 2018-170417 A

The polyimide films made from the diamine derived from dimer acid used in Patent Documents 1 and 2 exhibit excellent adhesion and low dielectric constant and dielectric loss tangent. However, since the diamine derived from dimer acid is a mixture containing trimer components and monomer components other than the dimer components, it has the aspect that it is difficult to control the molecular weight of the polyimide made from it. If the molecular weight control of the polyimide is insufficient, for example when a filler is blended, there is a problem that the resin film is easily weakened, and an improvement in this regard has been desired.

The object of the present invention is therefore to provide a polyimide that uses diamine derived from dimer acid as a raw material and that can effectively reduce the transmission loss of high-frequency signals while suppressing the weakening of the resin film.

As a result of intensive research, the inventors discovered that the above problems can be solved by using a dimer diamine composition that is purified as a diamine derived from dimer acid and controlling the weight average molecular weight and number average molecular weight of the polyimide within a predetermined range, thus completing the present invention.

The polyimide of the present invention is a polyimide containing a tetracarboxylic acid residue derived from a tetracarboxylic acid anhydride component and a diamine residue derived from a diamine component, and is characterized in that it satisfies the following conditions a to d:
a) The diamine composition contains 40 mol % or more of diamine residues derived from a dimer diamine composition mainly composed of a dimer diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, relative to the total diamine residues.
b) The weight average molecular weight (Mw) is in the range of 25,000 to 100,000.
c) The number average molecular weight (Mn) is in the range of 15,000 to 32,000.
d) The ratio of Mw to Mn (Mw/Mn) is in the range of 1.8 to 3.4.

The polyimide composition of the present invention comprises the following components (A) and (B):
(A) the polyimide;
and (B) a metal salt of an organic phosphinic acid;
and the weight ratio of the component (B) to the component (A) is within the range of 10 to 70% by weight.

The polyimide composition of the present invention is a polyimide composition comprising the component (A) having a ketone group in the molecule, and further comprising the following component (C):
(C) a crosslinking agent having a functional group that undergoes a nucleophilic addition reaction with the ketone group;
It may also contain:

The adhesive film of the present invention is characterized by containing the above-mentioned polyimide.

The adhesive film of the present invention comprises the following components (A) and (B):
(A) the polyimide;
And,
(B) a metal salt of an organic phosphinic acid;
and the weight ratio of the component (B) to the component (A) is within the range of 10 to 70% by weight.

The adhesive film of the present invention comprises the following components (A') and (B);
(A') a crosslinked polyimide having a crosslinked structure formed by a reaction between the polyimide having a ketone group in the molecule and a crosslinking agent having a functional group which undergoes a nucleophilic addition reaction with the ketone group;
And,
(B) a metal salt of an organic phosphinic acid;
and the weight ratio of the component (B) to the component (A') is within the range of 10 to 70% by weight.

The laminate of the present invention is a laminate having a substrate and an adhesive layer laminated on at least one surface of the substrate, the adhesive layer being made of the adhesive film described above.

The coverlay film of the present invention is a coverlay film having a coverlay film material layer and an adhesive layer laminated on the coverlay film material layer, and the adhesive layer is made of the adhesive film described above.

The resin-coated copper foil of the present invention is a resin-coated copper foil in which an adhesive layer and a copper foil are laminated, and the adhesive layer is made of the above-mentioned adhesive film.

The metal-clad laminate of the present invention is a metal-clad laminate having an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer, and at least one layer of the insulating resin layer is made of the above-mentioned adhesive film.

The metal-clad laminate of the present invention is a metal-clad laminate having an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer, and the adhesive layer is made of the above-mentioned adhesive film.

The metal-clad laminate of the present invention includes a first single-sided metal-clad laminate having a first metal layer and a first insulating resin layer laminated on at least one surface of the first metal layer;
a second single-sided metal-clad laminate having a second metal layer and a second insulating resin layer laminated on at least one surface of the second metal layer;
An adhesive layer is disposed so as to abut against the first insulating resin layer and the second insulating resin layer, and is laminated between the first single-sided metal-clad laminate and the second single-sided metal-clad laminate,
The adhesive layer is made of the above adhesive film.

The metal-clad laminate of the present invention comprises a single-sided metal-clad laminate having an insulating resin layer and a metal layer laminated on one side of the insulating resin layer, and an adhesive layer laminated on the other side of the insulating resin layer, the adhesive layer being made of the adhesive film.

The circuit board of the present invention is formed by wiring the metal layer of the metal-clad laminate.

The circuit board of the present invention is a circuit board comprising a first base material, a wiring layer laminated on at least one surface of the first base material, and an adhesive layer laminated on the surface of the first base material facing the wiring layer so as to cover the wiring layer, the adhesive layer being made of the adhesive film described above.

The circuit board of the present invention is a circuit board including a first substrate, a wiring layer laminated on at least one surface of the first substrate, an adhesive layer laminated on the surface of the first substrate facing the wiring layer so as to cover the wiring layer, and a second substrate laminated on the surface of the adhesive layer opposite the first substrate, the adhesive layer being made of the adhesive film described above.

The circuit board of the present invention is a circuit board comprising a first substrate, an adhesive layer laminated on at least one surface of the first substrate, a second substrate laminated on the surface of the adhesive layer opposite the first substrate, and wiring layers laminated on the surfaces of the first substrate and the second substrate opposite the adhesive layer, respectively, and the adhesive layer is made of the adhesive film described above.

The multilayer circuit board of the present invention is a multilayer circuit board comprising a laminate including a plurality of laminated insulating resin layers, and at least one wiring layer embedded inside the laminate, in which at least one of the plurality of insulating resin layers is formed of an adhesive layer that has adhesive properties and covers the wiring layer, and the adhesive layer is made of the adhesive film.

The polyimide of the present invention is made from a dimer diamine composition and has a controlled weight average molecular weight and number average molecular weight, which gives it excellent dielectric properties and prevents the resin film from becoming brittle. Therefore, when an adhesive film formed using the polyimide of the present invention is applied to a circuit board or the like that transmits high-frequency signals in the GHz band, it can effectively reduce transmission loss and has excellent strength and durability, contributing to improving the reliability of electronic devices.

1 is a schematic diagram showing a cross-sectional configuration of a laminate according to an embodiment of the present invention. 1 is a schematic diagram showing a cross-sectional configuration of a metal-clad laminate according to an embodiment of the present invention. FIG. 4 is a schematic diagram showing a cross-sectional configuration of a metal-clad laminate according to another embodiment of the present invention. FIG. 4 is a schematic diagram showing a cross-sectional configuration of a metal-clad laminate according to yet another embodiment of the present invention. 1 is a schematic diagram showing a cross-sectional configuration of a circuit board according to an embodiment of the present invention; FIG. 13 is a schematic diagram showing a cross-sectional configuration of a circuit board according to another embodiment of the present invention. FIG. 13 is a schematic diagram showing a cross-sectional configuration of a circuit board according to still another embodiment of the present invention. 1 is a schematic diagram showing a cross-sectional configuration of a multilayer circuit board according to an embodiment of the present invention;

The embodiment of the present invention will be explained with reference to the drawings as appropriate.

[Polyimide]
The polyimide according to one embodiment of the present invention has adhesiveness and satisfies the conditions a to d described below. Hereinafter, the polyimide according to this embodiment may be referred to as "adhesive polyimide". The adhesive polyimide contains a tetracarboxylic acid residue derived from a tetracarboxylic acid anhydride component and a diamine residue derived from a diamine component. In the present invention, the "tetracarboxylic acid residue" refers to a tetravalent group derived from a tetracarboxylic acid dianhydride, and the "diamine residue" refers to a divalent group derived from a diamine compound. When the raw materials tetracarboxylic acid anhydride and diamine compound are reacted in approximately equal moles, the types and molar ratios of the tetracarboxylic acid residue and diamine residue contained in the polyimide can be made to correspond approximately to the types and molar ratios of the raw materials.
In the present invention, the term "polyimide" refers to a resin made of a polymer having an imide group in the molecular structure, such as polyimide, polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, polybenzimidazoleimide, etc.

(Acid anhydride)
The adhesive polyimide may be made of any tetracarboxylic anhydride generally used in thermoplastic polyimides as a raw material, without any particular limitations. However, it is preferable to use a raw material containing 90 mol % or more of tetracarboxylic anhydrides represented by the following general formula (1) and/or (2) in total relative to the total tetracarboxylic anhydride components. In other words, it is preferable for the adhesive polyimide to contain 90 mol % or more of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by the following general formula (1) and/or (2) in total relative to the total tetracarboxylic acid residues. By containing 90 mol % or more of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by the following general formula (1) and/or (2) in total relative to the total tetracarboxylic acid residues, it is preferable that the adhesive polyimide is easily compatible with flexibility and heat resistance. If the total amount of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by the following general formula (1) and/or (2) is less than 90 mol %, the adhesive polyimide tends to have a low solvent solubility.

In general formula (1), X represents a single bond or a divalent group selected from the following formulas, and in general formula (2), the cyclic portion represented by Y represents a cyclic saturated hydrocarbon group selected from a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring.

In the above formula, Z represents —C ₆ H ₄ —, —(CH ₂ )n— or —CH ₂ —CH(—O—C(═O)—CH ₃ )—CH ₂ —, where n represents an integer of 1 to 20.

Examples of tetracarboxylic acid anhydrides represented by the above general formula (1) include 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), p-phenylenebis(trimellitic acid monoester anhydride) (TAHQ), and ethylene glycol bisanhydrotrimellitate (TMEG). Among these, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) is particularly preferred. When BTDA is used, the carbonyl group (ketone group) contributes to adhesion, so the adhesion of the adhesive polyimide can be improved. In addition, the ketone group present in the molecular skeleton of BTDA may react with the amino group of an amino compound for crosslinking, which will be described later, to form a C=N bond, which is likely to produce an effect of improving heat resistance. From this perspective, it is preferable that the tetracarboxylic acid residues derived from BTDA are contained in an amount of preferably 50 mol% or more, more preferably 60 mol% or more, of the total tetracarboxylic acid residues.

Examples of tetracarboxylic acid anhydrides represented by general formula (2) include 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,2,3,4-cyclopentane tetracarboxylic acid dianhydride, 1,2,4,5-cyclohexane tetracarboxylic acid dianhydride, 1,2,4,5-cycloheptane tetracarboxylic acid dianhydride, and 1,2,5,6-cyclooctane tetracarboxylic acid dianhydride.

The adhesive polyimide may contain tetracarboxylic acid residues derived from acid anhydrides other than the tetracarboxylic acid anhydrides represented by the above general formula (1) and general formula (2) within the scope of the invention. There are no particular limitations on such tetracarboxylic acid residues, and examples thereof include pyromellitic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'- or 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4'-diphenylethertetracarboxylic dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''- or 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,3',3,4''- ...4''-, 2,3',3,4''-, 2,3',3 ,2-Bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)methane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl) Tetrafluoropropane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene-1,4,5,8-(or 2,3 ,6,7-) tetracarboxylic acid dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic acid dianhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, and other aromatic tetracarboxylic acid dianhydrides are included.

(Diamine)
The adhesive polyimide may be made of any diamine compound generally used for thermoplastic polyimides as a raw material without any particular restrictions, but a raw material containing 40 mol % or more of a dimer diamine composition mainly composed of a dimer diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, relative to the total diamine components, is used. In other words, as explained in condition a below, the adhesive polyimide contains 40 mol % or more of diamine residues derived from a dimer diamine composition mainly composed of a dimer diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, relative to the total diamine residues.

The dimer diamine composition is a refined product that contains the following component (a) as the main component, with the amounts of components (b) and (c) controlled.

(a) dimer diamine;
The dimer diamine of the component (a) means a diamine in which two terminal carboxylic acid groups (-COOH) of a dimer acid are replaced by primary aminomethyl groups (-CH ₂ -NH ₂ ) or amino groups (-NH ₂ ). Dimer acid is a known dibasic acid obtained by intermolecular polymerization of unsaturated fatty acids, and its industrial production process is almost standardized in the industry, and is obtained by dimerizing unsaturated fatty acids having 11 to 22 carbon atoms using a clay catalyst or the like. Industrially obtained dimer acid is mainly composed of a dibasic acid having 36 carbon atoms obtained by dimerizing unsaturated fatty acids having 18 carbon atoms, such as oleic acid, linoleic acid, and linolenic acid, but contains any amount of monomer acid (having 18 carbon atoms), trimer acid (having 54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms depending on the degree of purification. In addition, although double bonds remain after the dimerization reaction, in the present invention, those which have been further subjected to a hydrogenation reaction to reduce the degree of unsaturation are also included in the dimer acid. The dimer diamine of the component (a) can be defined as a diamine compound obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having a carbon number of 18 to 54, preferably 22 to 44, with a primary aminomethyl group or an amino group.

Dimer diamine has the characteristic of being able to impart properties derived from the dimer acid skeleton. In other words, since dimer diamine is an aliphatic macromolecule with a molecular weight of approximately 560 to 620, it can increase the molecular molar volume and relatively reduce the polar groups of the polyimide. It is believed that such characteristics of dimer diamine contribute to improving the dielectric properties by reducing the relative dielectric constant and dielectric tangent while suppressing the deterioration of the heat resistance of the adhesive polyimide. In addition, since it has two freely moving hydrophobic chains with 7 to 9 carbon atoms and two chain-like aliphatic amino groups with a length close to 18 carbon atoms, it not only imparts flexibility to the polyimide, but also allows the polyimide to have an asymmetrical or non-planar chemical structure, which is believed to enable the polyimide to have a low dielectric constant.

It is advisable to use a dimer diamine composition in which the dimer diamine content of component (a) has been increased to 96% by weight or more, preferably 97% by weight or more, and more preferably 98% by weight or more, by a purification method such as molecular distillation. By increasing the dimer diamine content of component (a) to 96% by weight or more, it is possible to suppress the broadening of the molecular weight distribution of the polyimide. If technically possible, it is best that all of the dimer diamine composition (100% by weight) is composed of component (a) dimer diamine.

(b) a monoamine compound obtained by substituting a terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group;
The monobasic acid compound having 10 to 40 carbon atoms is a mixture of a monobasic unsaturated fatty acid having 10 to 20 carbon atoms derived from the raw material of dimer acid, and a monobasic acid compound having 21 to 40 carbon atoms which is a by-product during the production of dimer acid. The monoamine compound is obtained by substituting the terminal carboxylic acid group of these monobasic acid compounds with a primary aminomethyl group or an amino group.

The monoamine compound of component (b) is a component that suppresses the increase in molecular weight of the polyimide. During polymerization of the polyamic acid or polyimide, the monofunctional amino group of the monoamine compound reacts with the terminal acid anhydride group of the polyamic acid or polyimide, thereby blocking the terminal acid anhydride group and suppressing the increase in molecular weight of the polyamic acid or polyimide.

(c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the above-mentioned dimer diamine);
The polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms is a polybasic acid compound mainly composed of a tribasic acid compound having 41 to 80 carbon atoms, which is a by-product during the production of dimer acid. It may also contain a polymerized fatty acid other than dimer acid having 41 to 80 carbon atoms. The amine compound is obtained by substituting the terminal carboxylic acid group of these polybasic acid compounds with a primary aminomethyl group or an amino group.

The amine compound (c) is a component that promotes an increase in the molecular weight of the polyimide. The tri- or higher functional amino group, the main component of which is a triamine derived from trimer acid, reacts with the terminal acid anhydride group of the polyamic acid or polyimide, rapidly increasing the molecular weight of the polyimide. In addition, amine compounds derived from polymerized fatty acids other than dimer acids having 41 to 80 carbon atoms also increase the molecular weight of the polyimide, causing the polyamic acid or polyimide to gel.

When quantifying each component by measurement using gel permeation chromatography (GPC), in order to facilitate confirmation of the peak start, peak top, and peak end of each component of the dimer diamine composition, a sample of the dimer diamine composition treated with acetic anhydride and pyridine is used, and cyclohexanone is used as an internal standard. Using the sample thus prepared, each component is quantified by the area percentage of the GPC chromatogram. The peak start and peak end of each component are taken as the minimum values of each peak curve, and the area percentage of the chromatogram can be calculated based on this.

In addition, the dimer diamine composition has a total area percentage of components (b) and (c) of 4% or less, preferably less than 4%, in the chromatogram obtained by GPC measurement. By keeping the total area percentage of components (b) and (c) at 4% or less, the broadening of the molecular weight distribution of the polyimide can be suppressed.

The area percentage of the chromatogram of component (b) is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. By setting it in this range, it is possible to suppress a decrease in the molecular weight of the polyimide, and further to widen the range of the molar ratio of the tetracarboxylic anhydride component and the diamine component. Note that component (b) does not have to be included in the dimer diamine composition.

The area percentage of the chromatogram of component (c) is 2% or less, preferably 1.8% or less, and more preferably 1.5% or less. By setting it in this range, a sudden increase in the molecular weight of the polyimide can be suppressed, and further, an increase in the dielectric tangent of the resin film over a wide frequency range can be suppressed. Note that component (c) does not have to be included in the dimer diamine composition.

In addition, when the ratio (b/c) of the area percentages of the chromatograms of components (b) and (c) is 1 or more, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) is preferably 0.97 or more and less than 1.0, and such a molar ratio makes it easier to control the molecular weight of the polyimide.

In addition, when the ratio (b/c) of the area percentages of the components (b) and (c) in the chromatogram is less than 1, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) is preferably 0.97 or more and 1.1 or less, and by setting such a molar ratio, it becomes easier to control the molecular weight of the polyimide.

The dimer diamine composition is available as a commercially available product, and is preferably purified to reduce the amount of components other than the dimer diamine in component (a), for example to 96% by weight or more of component (a). There are no particular limitations on the purification method, but known methods such as distillation and precipitation purification are suitable. Examples of commercially available products include PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

The adhesive polyimide may contain diamine residues derived from diamine components other than those mentioned above. As such diamine residues, for example, diamine residues derived from diamine compounds represented by the general formulas (B1) to (B7) are preferred.

In formulae (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, linking group A independently represents a divalent group selected from -O-, -S-, -CO-, -SO-, -SO ₂ -, -COO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -NH- or -CONH-, and n ₁ independently represents an integer of 0 to 4. However, formula (B3) excluding those which overlap with formula (B2), and formula (B5) excluding those which overlap with formula (B4). Here, "independently" means that in one or two or more of formulae (B1) to (B7), multiple linking groups A, multiple R _1s or multiple n _1s may be the same or different. In the above formulas (B1) to (B7), the hydrogen atoms in the two terminal amino groups may be substituted, for example, -NR ₂ R ₃ (wherein R ₂ and R ₃ independently represent any substituent such as an alkyl group).

The diamine represented by formula (B1) (hereinafter sometimes referred to as "diamine (B1)") is an aromatic diamine having two benzene rings. In this diamine (B1), since an amino group directly bonded to at least one benzene ring and a divalent linking group A are at meta positions, the degree of freedom of the polyimide molecular chain is increased and the polyimide has high flexibility, which is considered to contribute to improving the flexibility of the polyimide molecular chain. Therefore, by using diamine (B1), the thermoplasticity of the polyimide is increased. Here, as the linking group A, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -CO-, -SO ₂ -, and -S- are preferable.

Examples of diamines (B1) include 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, and (3,3'-bisamino)diphenylamine.

The diamine represented by formula (B2) (hereinafter sometimes referred to as "diamine (B2)") is an aromatic diamine having three benzene rings. In this diamine (B2), the amino group directly bonded to at least one benzene ring and the divalent linking group A are in the meta position, which increases the degree of freedom of the polyimide molecular chain and gives it high flexibility, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B2) increases the thermoplasticity of the polyimide. Here, -O- is preferable as the linking group A.

Examples of diamines (B2) include 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzeneamine, and 3-[3-(4-aminophenoxy)phenoxy]benzeneamine.

The diamine represented by formula (B3) (hereinafter sometimes referred to as "diamine (B3)") is an aromatic diamine having three benzene rings. In this diamine (B3), two divalent linking groups A directly bonded to one benzene ring are in the meta position relative to each other, which increases the degree of freedom of the polyimide molecular chain and gives it high flexibility, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B3) increases the thermoplasticity of the polyimide. Here, -O- is preferred as the linking group A.

Examples of diamines (B3) include 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, and 4,4'-[5-methyl-(1,3-phenylene)bisoxy]bisaniline.

The diamine represented by formula (B4) (hereinafter sometimes referred to as "diamine (B4)") is an aromatic diamine having four benzene rings. This diamine (B4) has high flexibility due to the fact that the amino group directly bonded to at least one benzene ring and the divalent linking group A are at the meta position, and is considered to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B4) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -SO ₂ -, -CO-, or -CONH-.

Examples of diamines (B4) include bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)]benzophenone, and bis[4,4'-(3-aminophenoxy)]benzanilide.

The diamine represented by formula (B5) (hereinafter sometimes referred to as "diamine (B5)") is an aromatic diamine having four benzene rings. In this diamine (B5), two divalent linking groups A directly bonded to at least one benzene ring are mutually in meta positions, which increases the degree of freedom of the polyimide molecular chain and gives it high flexibility, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B5) enhances the thermoplasticity of the polyimide. Here, -O- is preferred as the linking group A.

Examples of diamines (B5) include 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline, etc.

The diamine represented by formula (B6) (hereinafter sometimes referred to as "diamine (B6)") is an aromatic diamine having four benzene rings. This diamine (B6) has high flexibility due to having at least two ether bonds, and is considered to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B6) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -C( _CH3 ) _2- , -O-, _-SO2- , or -CO-.

Examples of diamines (B6) include 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), and bis[4-(4-aminophenoxy)phenyl]ketone (BAPK).

The diamine represented by formula (B7) (hereinafter sometimes referred to as "diamine (B7)") is an aromatic diamine having four benzene rings. This diamine (B7) has a highly flexible divalent linking group A on both sides of the diphenyl skeleton, and is therefore thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B7) enhances the thermoplasticity of the polyimide. Here, -O- is preferred as the linking group A.

Examples of diamines (B7) include bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl, etc.

The adhesive polyimide preferably contains diamine residues derived from at least one diamine compound selected from diamines (B1) to (B7) in an amount of 1 mol % to 40 mol %, more preferably 5 mol % to 35 mol %, based on the total diamine residues. Diamines (B1) to (B7) have flexible molecular structures, so by using at least one diamine compound selected from these in an amount within the above range, the flexibility of the polyimide molecular chain can be improved and thermoplasticity can be imparted.

The adhesive polyimide may further contain diamine residues other than those mentioned above, provided that the effect of the invention is not impaired.

Adhesive polyimide can be produced by reacting the above-mentioned acid anhydride component and diamine component in a solvent to produce polyamic acid, which is then heated to close the ring. For example, the acid anhydride component and diamine component are dissolved in approximately equimolar amounts in an organic solvent, and the mixture is stirred at a temperature in the range of 0 to 100°C for 30 minutes to 24 hours to cause a polymerization reaction, thereby obtaining polyamic acid, which is a precursor of polyimide. In the reaction, the reaction components are dissolved so that the resulting precursor is in the range of 5 to 50% by weight in the organic solvent, preferably in the range of 10 to 40% by weight. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, methylcyclohexane, dioxane, tetrahydrofuran, diglyme, triglyme, methanol, ethanol, benzyl alcohol, and cresol. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The amount of such organic solvents used is not particularly limited, but it is preferable to adjust the amount so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight.

The synthesized polyamic acid is usually advantageously used as a reaction solvent solution, but it can be concentrated, diluted, or replaced with another organic solvent if necessary. Polyamic acid is also advantageously used because it generally has excellent solvent solubility. The viscosity of the polyamic acid solution is preferably within the range of 500 mPa·s to 100,000 mPa·s. If it is outside this range, defects such as uneven thickness and streaks are likely to occur in the film during coating operations using a coater, etc.

There are no particular limitations on the method for imidizing polyamic acid to form polyimide, and a suitable method is, for example, heat treatment in the solvent at a temperature in the range of 80 to 400°C for 1 to 24 hours. The temperature may be constant, or it may be changed during the process.

In adhesive polyimides, the physical properties such as dielectric properties, thermal expansion coefficient, tensile modulus, glass transition temperature, etc. can be controlled by selecting the types of the acid anhydride components and diamine components, and the respective molar ratios when two or more types of acid anhydride components or diamine components are used. In addition, when the adhesive polyimide has multiple structural units, they may be present as blocks or randomly, but it is preferable that they are present randomly.

The adhesive polyimide of this embodiment satisfies the following conditions a to d.

Condition a)
The diamine composition contains 40 mol % or more of diamine residues derived from a dimer diamine composition mainly composed of a dimer diamine obtained by substituting two terminal carboxylic acid groups of a dimer acid with primary aminomethyl groups or amino groups, relative to the total diamine residues.
By making the content of the diamine residue derived from the dimer diamine composition 40 mol % or more relative to the total diamine residues, the adhesive polyimide can be made soluble in a solvent. The content of the diamine residue derived from the dimer diamine composition is preferably 60 mol % or more, more preferably 60 to 100 mol %, relative to the total diamine residues. If it is less than 60 mol %, the relative dielectric constant and dielectric loss tangent tend to increase due to the relatively increased number of polar groups contained in the adhesive polyimide, but by making the content 60 mol % or more, the relative dielectric constant and dielectric loss tangent of the adhesive polyimide can be reduced.

Condition b)
Weight average molecular weight (Mw) is in the range of 25,000 to 100,000:
By making the Mw 25,000 or more, the tear strength and adhesive strength of the film can be improved, and the storage stability of the varnish can be increased. If the Mw is less than 25,000, the film becomes brittle, and in a film containing a filler (e.g., a metal salt of an organic phosphinic acid, which is a flame retardant), stress is generated at the interface between the filler and the resin when the film is bent or stretched, which causes breakage or generation of voids at the interface between the filler and the resin.
On the other hand, if Mw exceeds 100,000, the viscosity of the varnish increases and the handleability tends to decrease.
Within the above range, the lower the Mw, the narrower the molecular weight distribution tends to be, so the Mw is preferably in the range of 50,000 to 100,000, and more preferably in the range of 50,000 to 70,000.

Condition c)
Number average molecular weight (Mn) is in the range of 15,000 to 32,000:
Since Mn represents the number of polyimide chain ends more directly than Mw, an increase in highly polar ends in the polyimide molecular chain can be suppressed, and an increase in the relative dielectric constant and dielectric loss tangent can be suppressed by setting Mn to 15,000 or more, preferably 24,000 or more. Mn can be controlled by increasing the content of dimer diamine in the dimer diamine composition (i.e., by reducing the trimer component and monomer component), which can suppress the spread of the molecular weight of the adhesive polyimide.

Condition d)
The ratio of the Mw to the Mn (Mw/Mn) is within the range of 1.8 to 3.4:
The ratio Mw/Mn represents the degree of polydispersity, and in the adhesive polyimide of this embodiment, the ratio Mw/Mn is set to 1.8 or more. Even if Mn is about the same, the higher the degree of polydispersity, the higher the frequency of high molecular weight bodies, which increases the suppression of movement due to molecular entanglement, thereby achieving a low dielectric tangent and improved tear strength. In addition, by setting the ratio Mw/Mn to 3.4 or less and achieving a balance with Mn while ensuring a certain degree of polydispersity, it is possible to suppress an increase in highly polar ends in the polyimide molecular chain and suppress an increase in the relative dielectric constant and dielectric tangent.

The imide group concentration of the adhesive polyimide is preferably 22% by weight or less, more preferably 20% by weight or less. Here, "imide group concentration" means the value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire polyimide structure. If the imide group concentration exceeds 22% by weight, the molecular weight of the resin itself decreases, and the low moisture absorption property deteriorates due to an increase in polar groups, and Tg and elastic modulus increase.

The adhesive polyimide is most preferably a completely imidized structure. However, a part of the polyimide may be an amic acid. The imidization rate can be calculated from the absorbance of the C=O stretching derived from the imide group at 1780 cm ^-1 , based on the benzene ring absorber at about 1015 cm ^-1 , by measuring the infrared absorption spectrum of the polyimide thin film by the single reflection ATR method using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by JASCO Corporation).

(Crosslinking of adhesive polyimide)
When the adhesive polyimide has a ketone group, a crosslinked structure can be formed by reacting the ketone group with a crosslinking agent having a functional group that undergoes a nucleophilic addition reaction. The formation of the crosslinked structure can improve heat resistance. A polyimide having such a crosslinked structure (hereinafter sometimes referred to as a "crosslinked polyimide") is an application example of an adhesive polyimide, and is a preferred embodiment. Since the weight average molecular weight varies greatly due to the crosslinking, it is sufficient that the adhesive polyimide before the crosslinking satisfies the conditions a to d, and the crosslinked polyimide does not have to satisfy these conditions.

As the crosslinking agent, for example, it is preferable to use an amino compound having at least two primary amino groups as functional groups (hereinafter, sometimes referred to as "amino compound for crosslinking"). A crosslinked structure can be formed by reacting the ketone groups of the adhesive polyimide with the amino groups of the amino compound for crosslinking to form a C=N bond. In other words, the two primary amino groups in the amino compound function as functional groups that undergo a nucleophilic addition reaction with the ketone groups. Primary amino groups are particularly advantageous because they do not generate hydroxyl groups (-OH), which deteriorate the dielectric properties.

A preferred tetracarboxylic anhydride for forming an adhesive polyimide having a ketone group is, for example, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), and a preferred diamine compound is, for example, an aromatic diamine such as 4,4'-bis(3-aminophenoxy)benzophenone (BABP) or 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB). For the purpose of forming a crosslinked structure, it is particularly preferred to allow a crosslinking amino compound to act on the above adhesive polyimide, which contains, with respect to the total tetracarboxylic acid residues, preferably 50 mol % or more, more preferably 60 mol % or more of BTDA residues derived from BTDA. In the present invention, the term "BTDA residue" refers to a tetravalent group derived from BTDA.

Examples of amino compounds for forming crosslinks include (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds are prone to form crosslinked structures even at room temperature, which raises concerns about the storage stability of the varnish, while aromatic diamines require high temperatures to form crosslinked structures. In this way, when a dihydrazide compound is used, it is possible to achieve both the storage stability of the varnish and a shortened curing time. Examples of dihydrazide compounds include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, diglyceryl ester dihydrazide, ... Dihydrazide compounds such as cholic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoedioic acid dihydrazide, 4,4-bisbenzene dihydrazide, 1,4-naphthoic acid dihydrazide, 2,6-pyridine diacid dihydrazide, and itaconic acid dihydrazide are preferred. The above dihydrazide compounds may be used alone or in combination of two or more.

The above amino compounds, such as (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines, can also be used in combination of two or more types beyond the scope of the category, such as a combination of (I) and (II), a combination of (I) and (III), or a combination of (I), (II), and (III).

In order to make the mesh-like structure formed by the crosslinking with the crosslinking amino compound denser, the crosslinking amino compound used in the present invention preferably has a molecular weight (weight average molecular weight when the crosslinking amino compound is an oligomer) of 5,000 or less, more preferably 90 to 2,000, and even more preferably 100 to 1,500. Among these, crosslinking amino compounds having a molecular weight of 100 to 1,000 are particularly preferred. If the molecular weight of the crosslinking amino compound is less than 90, only one amino group of the crosslinking amino compound will form a C=N bond with a ketone group of the adhesive polyimide, and the surroundings of the remaining amino groups will be three-dimensionally bulky, making it difficult for the remaining amino groups to form C=N bonds.

When crosslinking the ketone groups in the adhesive polyimide with the crosslinking amino compound, the crosslinking amino compound is added to a resin solution containing the adhesive polyimide, and a condensation reaction occurs between the ketone groups in the adhesive polyimide and the primary amino groups of the crosslinking amino compound. This condensation reaction hardens the resin solution to form a hardened product.

A ketone group in the adhesive polyimide and a functional group of the crosslinking agent are subjected to a nucleophilic addition reaction to form a crosslink, resulting in a crosslinked polyimide, which is a cured product. The conditions of the nucleophilic addition reaction for forming the crosslink are not particularly limited and can be selected according to the type of the crosslinking agent. For example, when a primary amino group of an amino compound for forming a crosslink is reacted with a ketone group in the adhesive polyimide, an imine bond (C=N bond) is generated by a condensation reaction by heating, and a crosslinked structure is formed. The conditions of the condensation reaction for forming the crosslink are not particularly limited as long as the ketone group in the adhesive polyimide and the primary amino group of the amino compound for forming the crosslink form an imine bond (C=N bond). The temperature of the heat condensation is preferably within the range of 120 to 220°C, more preferably within the range of 140 to 200°C, for example, in order to release water generated by condensation out of the system, or to simplify the condensation step when a heat condensation reaction is performed subsequently after the synthesis of the adhesive polyimide. The reaction time is preferably about 30 minutes to 24 hours. The end point of the reaction can be confirmed by measuring the infrared absorption spectrum using, for example, a Fourier transform infrared spectrophotometer (commercially available: FT/IR620 manufactured by JASCO Corporation), based on the decrease or disappearance of the absorption peak derived from the ketone group in the polyimide resin at about 1670 cm ^-1 and the appearance of an absorption peak derived from the imine group at about 1635 cm ^-1 .

The thermal condensation of the ketone group of the adhesive polyimide with the primary amino group of the crosslinking amino compound can be carried out, for example, by the following method:
(1) A method in which, following synthesis (imidization) of an adhesive polyimide, an amino compound for crosslinking is added and heated;
(2) A method in which an excess amount of an amino compound is charged in advance as a diamine component, and following the synthesis (imidization) of an adhesive polyimide, the remaining amino compound that is not involved in imidization or amidation is used as an amino compound for crosslinking and heated together with the adhesive polyimide;
Or,
(3) A method in which the adhesive polyimide composition containing the above-mentioned crosslinking amino compound is processed into a predetermined shape (for example, after being applied to a substrate or formed into a film), and then heated;
This can be done by, etc.

In order to impart heat resistance to adhesive polyimide, an example of crosslinked polyimide with a crosslinked structure formed by the formation of imine bonds has been given, but the present invention is not limited to this. As a method for curing polyimide, it is also possible to mix and cure it with compounds having unsaturated bonds, such as epoxy resins, epoxy resin curing agents, maleimides, activated ester resins, and resins having a styrene skeleton.

[Polyimide composition]
The polyimide composition according to one embodiment of the present invention comprises the following components (A) and (B):
(A) an adhesive polyimide;
and (B) a metal salt of an organic phosphinic acid;
The polyimide composition contains an adhesive polyimide as a main component of the resin components, preferably 70% by weight or more of the resin components, more preferably 90% by weight or more of the resin components, and most preferably the entire resin components. The main component of the resin components means a component contained in an amount of more than 50% by weight of the entire resin components.

The metal salt of organic phosphinic acid of component (B) is a flame retardant that does not reduce the dielectric properties of the polyimide. As the metal salt of organic phosphinic acid of component (B), for example, an aluminum salt of organic phosphinic acid represented by the following general formula (3) is preferred.

In general formula (3), the two R's each independently represent an alkyl group. R is preferably a lower alkyl group having 1 to 4 carbon atoms.

As the metal salt of organic phosphinic acid of component (B), commercially available products can be used, such as Exolit OP935 (trade name, manufactured by Clariant).

In the polyimide composition according to the present embodiment, when the adhesive polyimide of component (A) is a polyimide having a ketone group in the molecule, the polyimide composition further contains, as an optional component, component (C);
(C) a crosslinking agent having a functional group that undergoes a nucleophilic addition reaction with the ketone group;
Here, the details of the polyimide having a ketone group in the molecule and the component (C) crosslinking agent are as described above.

[Composition ratio]
In the polyimide composition, the weight ratio of the metal salt of organic phosphinic acid of component (B) to the adhesive polyimide of component (A) is preferably within the range of 10 to 70% by weight. If the weight ratio of component (B) to component (A) is less than 10% by weight, the flame retardant effect of component (B) is not fully exhibited, and if it exceeds 70% by weight, the resin film (adhesive film) formed by the polyimide composition becomes brittle. For example, when the weight ratio of the metal salt of organic phosphinic acid of component (B) to the adhesive polyimide of component (A) is 25% by weight, the film elongation is 168%, whereas when it is 70% by weight, the film elongation is about 12%.

The polyimide composition preferably contains component (C) such that the functional groups of the crosslinking agent of component (C) are in the range of 0.04 to 0.50 mol, preferably 0.06 to 0.40 mol, in total, per mole of ketone groups contained in the adhesive polyimide of component (A). For example, when a crosslinking amino compound is used as component (C), the primary amino groups can be in the range of 0.04 to 0.50 mol, preferably 0.06 to 0.40 mol, in total, per mole of ketone groups.
If the total number of functional groups of the crosslinking agent is less than 0.04 moles per mole of ketone group, the crosslinking does not proceed sufficiently, and the heat resistance after curing tends to be difficult to exhibit. On the other hand, if the number exceeds 0.5 moles, the dielectric tangent tends to increase. This is presumably because the mobility of the polyimide molecular chain is restricted by the excess crosslinking agent, inhibiting the formation of an ordered structure of the molecular chain that is effective in suppressing the dielectric tangent during curing. In addition, if the amount of crosslinking agent is too large, the unreacted crosslinking agent acts as a thermoplasticizer, and tends to reduce the heat resistance of the adhesive layer.

In addition, since the adhesive polyimide is soluble in a solvent, it can be used in the form of a composition containing a solvent. In other words, it is preferable that the polyimide composition contains, as an optional component, a solvent capable of dissolving the adhesive polyimide.

There are no particular limitations on the solvent as long as it can dissolve the adhesive polyimide, and examples of the solvent include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, methylcyclohexane, dioxane, tetrahydrofuran, diglyme, triglyme, methanol, ethanol, benzyl alcohol, cresol, and acetone. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination.

In the polyimide composition, the blending ratio of adhesive polyimide and solvent is not particularly limited as long as the viscosity of the composition can be maintained at a level that allows it to be coated. The viscosity of the polyimide composition is preferably within the range of 500 mPa·s to 100,000 mPa·s, for example. If it is outside this range, defects such as uneven thickness and streaks are likely to occur in the resin film during the coating process.

The polyimide composition may contain optional components, such as plasticizers, other curable resin components such as epoxy resins, curing agents, curing accelerators, organic fillers, inorganic fillers, coupling agents, solvents, and flame retardants, as appropriate, within the scope of the invention.

[Adhesive film]
The adhesive film according to one embodiment of the present invention is a resin film obtained by processing the adhesive polyimide or crosslinked polyimide into a film. The adhesive film may be a film containing the adhesive polyimide or crosslinked polyimide as the main component of the resin component, preferably 70% by weight or more of the resin component, more preferably 90% by weight or more of the resin component, and most preferably the entire resin component. The main component of the resin component means a component contained in an amount of more than 50% by weight of the total resin component. The adhesive film may be a film (sheet) made of adhesive polyimide or crosslinked polyimide, or may be laminated on a resin substrate such as an inorganic material substrate, such as copper foil or glass plate, or a polyimide film, polyamide film, or polyester film. The adhesive film may be appropriately blended with optional components such as plasticizers, other curable resin components such as epoxy resins, curing agents, curing accelerators, organic fillers, inorganic fillers, coupling agents, and flame retardants.

A preferred embodiment of the adhesive film of the present invention comprises the following components (A) and (B):
(A) an adhesive polyimide;
And,
(B) a metal salt of an organic phosphinic acid;
In this regard, the contents of the adhesive polyimide of component (A) and the metal salt of an organic phosphinic acid of component (B) are as described above.

Another preferred embodiment of the adhesive film of the present invention comprises the following components (A′) and (B);
(A') a crosslinked polyimide which is an adhesive polyimide having a ketone group in the molecule and which forms a crosslinked structure by a reaction between a polyimide and a crosslinking agent having a functional group which undergoes a nucleophilic addition reaction with the ketone group;
And,
(B) a metal salt of an organic phosphinic acid;
The crosslinked polyimide of component (A') and the metal salt of an organic phosphinic acid of component (B) are as described above.

The adhesive film preferably has a dielectric loss tangent (Tan _δ10 ) of 0.003 or less, more preferably 0.0025 or less, and a relative dielectric constant ( _E10 ) of 3.0 or less at 10 GHz, as measured by a split post dielectric resonator (SPDR) after 24 hours of conditioning under constant temperature and humidity conditions (normal state) of 23°C and 50% RH. If the dielectric loss tangent (Tan _δ10 ) and the relative dielectric constant ( _E10 ) are below the above values, an increase in dielectric loss is suppressed when the adhesive film is applied to a circuit board, and the occurrence of problems such as loss of electrical signals on the transmission path of high frequency signals can be suppressed.

Furthermore, the adhesive film preferably has a dielectric loss tangent (Tan _δ20 ) of 0.003 or less, more preferably 0.0025 or less, and a relative dielectric constant ( _E20 ) of 3.0 or less at 20 GHz, as measured by a split post dielectric resonator (SPDR) after 24 hours of conditioning under constant temperature and humidity conditions (normal state) of 23°C and 50% RH. If the dielectric loss tangent (Tan _δ20 ) and the relative dielectric constant ( _E20 ) are below the above values, an increase in dielectric loss is suppressed when the adhesive film is applied to a circuit board, and the occurrence of inconveniences such as loss of electrical signals on the transmission path of high-frequency signals can be suppressed.

Furthermore, after conditioning the adhesive film for 24 hours under constant temperature and humidity conditions (normal state) of 23°C and 50% RH, it is preferable that the difference (Tan δ ₂₀ -Tan δ ₁₀ ) between the dielectric tangent (Tan δ ₂₀ ) at 20 GHz and the dielectric tangent (Tan δ ₁₀ ) at 10 GHz measured with a split post dielectric resonator (SPDR) is 0 or less. A difference (Tan δ ₂₀ -Tan δ ₁₀ ) of 0 or less means that the transmission loss from 10 to 20 GHz does not increase, but remains the same or even decreases.

The tensile modulus of the adhesive film is preferably 3000 MPa or less, more preferably 100 MPa to 2500 MPa, and even more preferably 200 MPa to 2000 MPa. If the tensile modulus is less than 100 MPa, the film is prone to wrinkles, and handling may be impaired due to air entrapment during lamination. If the tensile modulus exceeds 3000 MPa, warping may occur and dimensional stability may decrease when the substrate and adhesive film are laminated. By setting the tensile modulus to the above range, a laminate with good handling properties, suppressed warping, and excellent dimensional stability can be obtained.

The elongation of the adhesive film is preferably 50% or more, more preferably 100% or more, and even more preferably 150% or more. If the elongation is less than 50%, the flexibility of the laminate, such as a circuit board, will decrease, and bending the laminate may cause it to break. In addition, if the elongation is low during handling, voids will occur between the filler and the adhesive, causing the entire film to become cloudy, which may cause defects in appearance and characteristics. By setting the elongation at the above level, it is possible to obtain a laminate that has good handling properties and sufficient bending resistance after being made into a multilayer FPC.

The method for producing the adhesive film of the present embodiment is not particularly limited, but the following methods [1] to [3] can be exemplified.
[1] A method in which an adhesive polyimide is applied in a solution state (for example, in a polyimide composition state) to an arbitrary substrate to form a coating film, which is then dried at a temperature of, for example, 80 to 180° C. to form a film, and then peeled off from the substrate as necessary.
[2] A method in which a solution of a polyamic acid, which is a precursor of an adhesive polyimide, is applied to any substrate, dried, and then imidized to form a film, which is then peeled off from the substrate as necessary.
[3] A method in which a solution of polyamic acid, which is a precursor of adhesive polyimide, is applied to any substrate and dried, and then the gel film of polyamic acid is peeled off from the substrate and imidized to form an adhesive film.
The method for applying the adhesive polyimide solution (or polyamic acid solution) onto the substrate is not particularly limited, and it is possible to apply it using, for example, a coater such as a comma, die, knife or lip coater.

Next, we will explain the preferred embodiments of the laminate, metal-clad laminate, circuit board, and multilayer circuit board that use the resin film by giving specific examples.

[Laminate]
The laminate 100 according to one embodiment of the present invention has a substrate 10 and an adhesive layer 20 laminated on at least one surface of the substrate 10, as shown in FIG. 1, and the adhesive layer 20 is made of the adhesive film. The laminate 100 may include any layer other than the above. The substrate 10 in the laminate 100 may be, for example, a substrate made of an inorganic material such as copper foil or a glass plate, or a substrate made of a resin material such as a polyimide film, a polyamide film, or a polyester film. The laminate 100 can be manufactured according to any one of the manufacturing methods [1] to [3] of the adhesive film, except that the substrate 10 is not peeled off from the substrate 10. The laminate 100 may also be manufactured by preparing the substrate 10 and the adhesive film separately and laminating them together.
Preferred embodiments of the laminate 100 include a coverlay film, a copper foil with resin, and the like.

(Coverlay film)
The coverlay film, which is one embodiment of the laminate 100, is used to protect a wiring layer in a circuit board, and although not shown, has a coverlay film material layer as a base material 10 and an adhesive layer 20 laminated on one side of the coverlay film material layer, the adhesive layer 20 being made of the above-mentioned adhesive film. The coverlay film may include any layer other than those described above.

The material of the coverlay film material layer is not particularly limited, but may be, for example, a polyimide-based film such as polyimide resin, polyetherimide resin, or polyamideimide resin, a polyamide-based film, or a polyester-based film. Of these, it is preferable to use a polyimide-based film with excellent heat resistance. In addition, the coverlay film material may contain a black pigment to effectively exhibit light-shielding properties, concealing properties, design properties, etc., and may contain optional components such as a matte pigment that suppresses surface gloss, as long as the effect of improving the dielectric properties is not impaired.

The thickness of the coverlay film material layer is not particularly limited, but is preferably within the range of, for example, 5 μm or more and 100 μm or less.
The thickness of the adhesive layer 20 is not particularly limited, but is preferably within the range of 10 μm to 75 μm, for example.

The coverlay film of the present embodiment can be produced by the method exemplified below.
First, as a first method, polyimide that will become the adhesive layer 20 is applied in a solution state (for example, a varnish state containing a solvent is preferable, and a polyimide composition is preferable) to one side of a film material layer for the coverlay, and then the adhesive layer 20 is formed by drying at a temperature of, for example, 80 to 180° C., thereby forming a coverlay film having a film material layer for the coverlay and the adhesive layer 20.

As a second method, the polyimide for the adhesive layer 20 is applied in a solution state (for example, a varnish containing a solvent is preferable, and a polyimide composition is preferable) onto any substrate, dried at a temperature of, for example, 80 to 180°C, and then peeled off to form a resin film for the adhesive layer 20. This resin film is then thermocompressed with a film material layer for the coverlay at a temperature of, for example, 60 to 220°C to form a coverlay film.

(Copper foil with resin)
The resin-coated copper foil, which is another embodiment of the laminate 100, is used as a circuit board material, and although not shown, is obtained by laminating an adhesive layer 20 on at least one side of a copper foil as a substrate 10, and the adhesive layer 20 is made of the above-mentioned adhesive film. The resin-coated copper foil of this embodiment may include any layer other than those described above.

The thickness of the adhesive layer 20 in the resin-coated copper foil is preferably within the range of 0.1 to 125 μm, for example, and more preferably within the range of 0.3 to 100 μm. If the thickness of the adhesive layer 20 is less than the above lower limit, problems such as inability to ensure sufficient adhesion may occur. On the other hand, if the thickness of the adhesive layer 20 exceeds the above upper limit, problems such as reduced dimensional stability may occur. Also, from the viewpoint of lowering the dielectric constant and the dielectric loss tangent, it is preferable that the thickness of the adhesive layer 20 is 3 μm or more.

The material of the copper foil in the resin-coated copper foil is preferably one whose main component is copper or a copper alloy. The thickness of the copper foil is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoint of production stability and handling, the lower limit of the copper foil thickness is preferably 5 μm. The copper foil may be a rolled copper foil or an electrolytic copper foil. In addition, commercially available copper foils can be used as the copper foil.

The resin-coated copper foil may be prepared, for example, by sputtering a metal onto an adhesive film to form a seed layer, and then forming a copper layer, for example, by copper plating, or by laminating an adhesive film and a copper foil by a method such as thermocompression bonding. Furthermore, the resin-coated copper foil may be prepared by casting a coating solution of an adhesive polyimide or its precursor onto the copper foil, drying it to form a coating film, and then carrying out the necessary heat treatment to form an adhesive layer 20 on the copper foil.

[Metal-clad laminate]
(First aspect)
The metal-clad laminate according to one embodiment of the present invention is used as a circuit board material and includes an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer, at least one layer of the insulating resin layer being made of the adhesive film. Note that the metal-clad laminate according to this embodiment may include any layer other than those described above.

(Second Aspect)
A metal-clad laminate according to another embodiment of the present invention is a so-called three-layer metal-clad laminate 101 including an insulating resin layer 30, an adhesive layer 20 laminated on at least one surface of the insulating resin layer 30, and a metal layer M laminated on the insulating resin layer 30 via the adhesive layer 20, as shown in FIG. 2, and the adhesive layer 20 is made of the above-mentioned adhesive film. The three-layer metal-clad laminate 101 may include any layer other than the above. The three-layer metal-clad laminate 101 may have the adhesive layer 20 on one or both surfaces of the insulating resin layer 30, and the metal layer M may be provided on one or both surfaces of the insulating resin layer 30 via the adhesive layer 20. In other words, the three-layer metal-clad laminate 101 may be a single-sided metal-clad laminate or a double-sided metal-clad laminate. A single-sided or double-sided FPC can be manufactured by etching the metal layer M of the three-layer metal-clad laminate 101 to perform wiring circuit processing.

The insulating resin layer 30 in the three-layer metal-clad laminate 101 is not particularly limited as long as it is made of a resin having electrical insulation properties, and examples thereof include polyimide, epoxy resin, phenolic resin, polyethylene, polypropylene, polytetrafluoroethylene, silicone, ETFE, etc., but is preferably made of polyimide. The polyimide layer constituting the insulating resin layer 30 may be a single layer or multiple layers, but preferably includes a non-thermoplastic polyimide layer.

The thickness of the insulating resin layer 30 in the three-layer metal-clad laminate 101 is preferably within the range of 1 to 125 μm, for example, and more preferably within the range of 5 to 100 μm. If the thickness of the insulating resin layer 30 is less than the above lower limit, problems such as inability to ensure sufficient electrical insulation may occur. On the other hand, if the thickness of the insulating resin layer 30 exceeds the above upper limit, problems such as the metal-clad laminate becoming more susceptible to warping may occur.

The thickness of the adhesive layer 20 in the three-layer metal-clad laminate 101 is preferably, for example, in the range of 0.1 to 125 μm, and more preferably in the range of 0.3 to 100 μm. In the three-layer metal-clad laminate 101 of this embodiment, if the thickness of the adhesive layer 20 is less than the above-mentioned lower limit, problems such as inability to ensure sufficient adhesion may occur. On the other hand, if the thickness of the adhesive layer 20 exceeds the above-mentioned upper limit, problems such as reduced dimensional stability may occur. In addition, from the viewpoint of reducing the dielectric constant and dielectric loss tangent of the entire insulating layer, which is a laminate of the insulating resin layer 30 and the adhesive layer 20, the thickness of the adhesive layer 20 is preferably 3 μm or more.

The ratio of the thickness of the insulating resin layer 30 to the thickness of the adhesive layer 20 (thickness of the insulating resin layer 30/thickness of the adhesive layer 20) is preferably in the range of 0.1 to 3.0, and more preferably in the range of 0.15 to 2.0. By setting such a ratio, warping of the three-layer metal-clad laminate 101 can be suppressed. The insulating resin layer 30 may contain a filler as necessary. Examples of fillers include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, and metal salts of organic phosphinic acid. These can be used alone or in a mixture of two or more types.

(Third Aspect)
A metal-clad laminate according to yet another embodiment of the present invention is, for example, as shown in Fig. 3, a laminated type metal-clad laminate 102 formed by laminating at least two single-sided metal-clad laminates via an adhesive layer 20. The laminated type metal-clad laminate 102 comprises a first single-sided metal-clad laminate 41, a second single-sided metal-clad laminate 42, and an adhesive layer 20 laminated between the first single-sided metal-clad laminate 41 and the second single-sided metal-clad laminate 42, and the adhesive layer 20 is made of the adhesive film.
Here, the first single-sided metal-clad laminate 41 has a first metal layer M1 and a first insulating resin layer 31 laminated on at least one side of the first metal layer M1. The second single-sided metal-clad laminate 42 has a second metal layer M2 and a second insulating resin layer 32 laminated on at least one side of the second metal layer M2. The adhesive layer 20 is disposed so as to abut against the first insulating resin layer 31 and the second insulating resin layer 32. The laminated metal-clad laminate 102 may include any layer other than those described above.

The first insulating resin layer 31 and the second insulating resin layer 32 in the laminated type metal-clad laminate 102 may have the same configuration as the insulating resin layer 30 in the three-layer metal-clad laminate 101 of the second embodiment.
The laminated metal-clad laminate 102 can be manufactured by preparing a first single-sided metal-clad laminate 41 and a second single-sided metal-clad laminate 42, and placing an adhesive film between the first insulating resin layer 31 and the second insulating resin layer 32 and laminating them together.

(Fourth aspect)
4, a metal-clad laminate according to still another embodiment of the present invention is a metal-clad laminate 103 with an adhesive layer, which includes a single-sided metal-clad laminate having an insulating resin layer 33 and a metal layer M laminated on one side of the insulating resin layer 33, and an adhesive layer 20 laminated on the other side of the insulating resin layer 33, the adhesive layer 20 being made of the above-mentioned adhesive film. Note that the metal-clad laminate 103 with an adhesive layer may include any layer other than those described above.
The insulating resin layer 33 in the adhesive layer-attached metal-clad laminate 103 may have a configuration similar to that of the insulating resin layer 30 in the three-layer metal-clad laminate 101 of the second embodiment.
The adhesive layer-attached metal-clad laminate 103 can be manufactured by preparing a single-sided metal-clad laminate having an insulating resin layer 33 and a metal layer M, and laminating an adhesive film to the insulating resin layer 33 side.

In any of the first to fourth exemplary embodiments of the metal-clad laminates described above, the material of the metal layer M (including the first metal layer M1 and the second metal layer M2; the same applies below) is not particularly limited, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, copper or copper alloys are particularly preferred. The material of the wiring layer in the circuit board described below is also the same as that of the metal layer M.

The thickness of the metal layer M is not particularly limited, but when a metal foil such as copper foil is used, it is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoint of production stability and handling, it is preferable that the lower limit of the thickness of the metal foil is 5 μm. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. In addition, commercially available copper foil may be used as the copper foil. In addition, the metal foil may be subjected to a surface treatment, for example, with siding, aluminum alcoholate, aluminum chelate, silane coupling agent, etc., for the purpose of, for example, rust prevention treatment and improvement of adhesive strength.

[Circuit board]
(First aspect)
The circuit board according to the embodiment of the present invention is formed by wiring the metal layer of the metal-clad laminate according to any of the above embodiments. One or more metal layers of the metal-clad laminate are patterned by a conventional method to form a wiring layer (conductor circuit layer), thereby manufacturing a circuit board such as an FPC. The circuit board may include a coverlay film that covers the wiring layer.

(Second Aspect)
5, a circuit board 200 according to another embodiment of the present invention includes a first base material 11, a wiring layer 50 laminated on at least one surface of the first base material 11, and an adhesive layer 20 laminated on the surface of the first base material 11 facing the wiring layer 50 so as to cover the wiring layer 50, the adhesive layer 20 being made of the adhesive film. Note that the circuit board 200 may include any layer other than those described above.
The first substrate 11 in the circuit board 200 may have the same configuration as the insulating resin layer of the metal-clad laminate. The circuit board 200 can be manufactured by laminating an adhesive film to the wiring layer 50 side of a circuit board including the first substrate 11 and a wiring layer 50 laminated on at least one surface of the first substrate 11.

(Third Aspect)
As shown in FIG. 6, the circuit board 201 according to another embodiment of the present invention includes a first substrate 11, a wiring layer 50 laminated on at least one surface of the first substrate 11, an adhesive layer 20 laminated on the surface of the first substrate 11 facing the wiring layer 50 so as to cover the wiring layer 50, and a second substrate 12 laminated on the surface of the adhesive layer 20 opposite the first substrate 11, and the adhesive layer 20 is made of the adhesive film. The circuit board 201 may include any layer other than those described above. The first substrate 11 and the second substrate 12 in the circuit board 201 may have the same configuration as the insulating resin layer of the metal-clad laminate.
The circuit board 201 can be manufactured by bonding a second substrate 12 to the wiring layer 50 side of a circuit board having a first substrate 11 and a wiring layer 50 laminated on at least one surface of the first substrate 11 via an adhesive film.

(Fourth aspect)
A circuit board 202 according to another embodiment of the present invention includes, as shown in FIG. 7, a first substrate 11, an adhesive layer 20 laminated on at least one surface of the first substrate 11, a second substrate 12 laminated on the surface of the adhesive layer 20 opposite the first substrate 11, and wiring layers 50, 50 laminated on the surfaces of the first substrate 11 and the second substrate 12 opposite the adhesive layer 20, respectively, and the adhesive layer 20 is made of the adhesive film. The circuit board 202 may include any layer other than the above. The first substrate 11 and the second substrate 12 in the circuit board 202 may have the same configuration as the insulating resin layer of the metal-clad laminate.
The circuit board 202 can be manufactured by preparing a first circuit board having a first substrate 11 and a wiring layer 50 laminated on at least one surface of the first substrate 11, and a second circuit board having a second substrate 12 and a wiring layer 50 laminated on at least one surface of the second substrate 12, and then placing an adhesive film between the first substrate 11 of the first circuit board and the second substrate 12 of the second circuit board and bonding them together.

[Multilayer circuit board]
A multilayer circuit board according to an embodiment of the present invention includes a laminate in which a plurality of insulating resin layers are laminated, and one or more wiring layers embedded inside the laminate, and at least one of the plurality of insulating resin layers is formed of an adhesive layer 20 that has adhesiveness and covers the wiring layer, and the adhesive layer 20 is made of the adhesive film. Note that the multilayer circuit board of this embodiment may include any layer other than those described above.
For example, as shown in FIG. 8, the multilayer circuit board 203 of this embodiment has at least two insulating resin layers 34 and at least two wiring layers 50, and at least one of the wiring layers 50 is covered with an adhesive layer 20. The adhesive layer 20 covering the wiring layer 50 may partially cover the surface of the wiring layer 50, or may cover the entire surface of the wiring layer 50. The multilayer circuit board 203 may also have a wiring layer 50 exposed on the surface of the multilayer circuit board 203. The multilayer circuit board 203 may also have an interlayer connection electrode (via electrode) in contact with the wiring layer 50. The wiring layer 50 is a conductor circuit formed in a predetermined pattern on one or both sides of the insulating resin layer 34. The conductor circuit may be patterned on the surface of the insulating resin layer 34, or may be patterned in a damascene (embedded) manner. The insulating resin layer 34 in the multilayer circuit board 203 may have the same configuration as the insulating resin layer of the metal-clad laminate.

The circuit board and multilayer circuit board of each of the above embodiments have an adhesive layer 20 containing adhesive polyimide or crosslinked polyimide with controlled Mw and Mn, and therefore have excellent adhesive properties, and even if a filler is contained, the decrease in mechanical strength is suppressed, and it is possible to reduce transmission loss in the transmission of high-frequency signals.

The following examples are provided to more specifically explain the features of the present invention. However, the scope of the present invention is not limited to the examples. In the following examples, the various measurements and evaluations are as follows, unless otherwise noted.

[Method for measuring amine value]
Approximately 2 g of the dimer diamine composition is weighed into a 200-250 mL Erlenmeyer flask, and phenolphthalein is used as an indicator. A 0.1 mol/L ethanolic potassium hydroxide solution is added dropwise until the solution turns light pink, and the composition is dissolved in approximately 100 mL of neutralized butanol. 3-7 drops of phenolphthalein solution are added thereto, and titration is performed with 0.1 mol/L ethanolic potassium hydroxide solution while stirring until the sample solution turns light pink. Five drops of bromophenol blue solution are added thereto, and titration is performed with 0.2 mol/L hydrochloric acid/isopropanol solution while stirring until the sample solution turns yellow.
The amine value is calculated according to the following formula (1).
Amine value = {(V ₂ × C ₂ ) - (V ₁ × C ₁ )} × M _KOH / m (1)
Here, the amine value is a value expressed in mg-KOH/g, M _KOH is the molecular weight of potassium hydroxide, 56.1, V and C are the volume and concentration of the solution used in the titration, respectively, and the subscripts 1 and 2 represent a 0.1 mol/L ethanolic potassium hydroxide solution and a 0.2 mol/L hydrochloric acid/isopropanol solution, respectively, and m is the sample weight expressed in grams.

[Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn) of polyimide]
The measurement was performed by gel permeation chromatography (manufactured by Tosoh Corporation, product name: HLC-8220GPC). Polystyrene was used as a standard substance, and tetrahydrofuran (THF) was used as a developing solvent.

[GPC and Chromatogram Area Percentage Calculation]
For GPC, 20 mg of the dimer diamine composition was pretreated with 200 μL of acetic anhydride, 200 μL of pyridine, and 2 mL of THF to prepare a 100 mg solution, which was then diluted with 10 mL of THF (containing 1000 ppm of cyclohexanone). The prepared sample was measured using a Tosoh Corporation product name: HLC-8220GPC under the following conditions: column: TSK-gel G2000HXL, G1000HXL, flow rate: 1 mL/min, column (oven) temperature: 40° C., injection amount: 50 μL. Cyclohexanone was treated as a standard substance for the correction of the elution time.

In this case, the retention times were adjusted so that the peak top of the cyclohexanone main peak was at a retention time of 27 to 31 minutes, and the period from the peak start to the peak end of the cyclohexanone main peak was 2 minutes, and the peak top of the main peak excluding the cyclohexanone peak was at a retention time of 18 to 19 minutes, and the period from the peak start to the peak end of the main peak excluding the cyclohexanone peak was at a retention time of 2 minutes to 4 minutes 30 seconds,
(a) Component represented by the main peak;
(b) a component represented by a GPC peak detected at a time later than the minimum retention time of the main peak;
(c) a component represented by a GPC peak detected at a time earlier than the minimum retention time of the main peak;
was detected.

[Dielectric property evaluation]
Using a vector network analyzer (manufactured by Agilent, product name: Vector Network Analyzer E8363C) and a split post dielectric resonator (SPDR), a resin sheet that had been heat-treated with a small precision press machine manufactured by Kitagawa Seiki under conditions of temperature; 160°C, pressure; 2 MPa, and 1.0 hour was left for 24 hours under conditions of temperature; 23°C and humidity; 50%, and then the relative dielectric constant (Dk) and dielectric loss tangent (Df) were measured at frequencies of 5 GHz, 10 GHz, and 20 GHz.

[Measurement of tensile modulus, strength, and elongation]
A tension tester (trade name Tensilon, manufactured by Orientec Co., Ltd.) was used to carry out a tensile test at 50 mm/min using a test piece having a width of 12.7 mm and a length of 127 mm, and the tensile modulus, strength and elongation were measured.

The abbreviations used in the examples represent the following compounds.
BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride DDA1: product name: PRIAMINE 1074, manufactured by Croda Japan Co., Ltd., purified (component a: 97.9% by weight, component b: 0.3%, component c: 1.8%, amine value: 210 mg KOH/g, mixture of dimer diamines having a cyclic structure and a chain structure)
DDA2: product name: PRIAMINE 1075, manufactured by Croda Japan Co., Ltd., purified (component a: 98.3% by weight, component b: 0%, component c: 1.7%, amine value: 210 mg KOH/g, mixture of dimer diamines having a cyclic structure and a chain structure)
N-12: dodecanedioic acid dihydrazide NMP: N-methyl-2-pyrrolidone OP935: aluminum salt of phosphinic acid (manufactured by Clariant, trade name: Exolit OP935, aluminum diethylphosphinate, phosphorus content: 23 mass%, particle size D ₅₀ : 2 μm)
In the above DDA1 and DDA2, the "%" of the b component and the c component means the area percentage of the chromatogram in the GPC measurement. The molecular weights of DDA1 and DDA2 were calculated by the following formula (1).
Molecular weight = 56.1 × 2 × 1000 / amine value (1)

(Reference Example 1)
<Preparation of polyimide solution>
A polyamic acid solution was prepared by charging 34.94 g of BTDA (0.108 mol), 55.06 g of DDA1 (0.103 mol), 126 g of NMP, and 84 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 64 g of xylene was added to complete the imidization, preparing polyimide solution 1 (solid content: 30 wt %, Mw: 20,165, Mn: 12,259, Mw/Mn: 1.64).

<Preparation of Polyimide Composition>
To 150 g of polyimide solution 1, 1.575 g of N-12 (corresponding to 0.35 mol of primary amine groups per 1 mol of ketone groups of BTDA) was added, and the mixture was diluted with 5.0 g of NMP. Further, 11.25 g of OP935 (25 wt % with respect to the solid content of polyimide, corresponding to 0.09 mol as phosphorus content per 1 mol of dimer diamine) was added, and the mixture was stirred for another 1 hour to prepare polyimide composition 1.

<Preparation of Resin Sheet>
The polyimide composition 1 was applied to one side of a release PET film (manufactured by Higashiyama Film Co., Ltd., product name: HY-S05, length × width × thickness = 200 mm × 300 mm × 25 μm), dried at 80° C. for 15 minutes, and peeled off from the release PET film to prepare a resin sheet 1 with a thickness of 25 μm.

The various properties of the resin sheet 1 are as follows.
Dielectric constant at 5 GHz: 2.7, dielectric tangent: 0.0031
Dielectric constant at 10 GHz: 2.7, dielectric tangent: 0.0027
Dielectric constant at 20 GHz: 2.6, dielectric tangent: 0.0020
Tensile modulus: 0.6 GPa, strength: 21 MPa, elongation: 222%

(Reference Example 2)
A polyamic acid solution was prepared by charging 34.53 g of BTDA (0.106 mol), 55.47 g of DDA1 (0.104 mol), 126 g of NMP, and 84 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 64 g of xylene was added to complete the imidization, preparing polyimide solution 2 (solid content: 30 wt %, Mw: 25,779, Mn: 14,853, Mw/Mn: 1.74).

Polyimide composition 2 and resin sheet 2 were prepared in the same manner as in Reference Example 1, except that the amount of N-12 was 1.546 g.

The various characteristics of the resin sheet 2 are as follows.
Dielectric constant at 5 GHz: 2.7, dielectric tangent: 0.0030
Dielectric constant at 10 GHz: 2.7, dielectric tangent: 0.0025
Dielectric constant at 20 GHz: 2.6, dielectric tangent: 0.0019
Tensile modulus: 0.6 GPa, strength: 23 MPa, elongation: 215%

[Example 1]
A polyamic acid solution was prepared by charging 33.94 g of BTDA (0.105 mol), 55.06 g of DDA2 (0.105 mol), 126 g of NMP, and 84 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 84 g of xylene was added to complete the imidization, preparing polyimide solution 3 (solid content: 30 wt %, Mw: 38,818, Mn: 20,569, Mw/Mn: 1.89).

Polyimide composition 3 and resin sheet 3 were prepared in the same manner as in Reference Example 1, except that the amount of N-12 was 1.531 g.

The various characteristics of the resin sheet 3 are as follows.
Dielectric constant at 5 GHz: 2.7, dielectric tangent: 0.0026
Dielectric constant at 10 GHz: 2.7, dielectric tangent: 0.0022
Dielectric constant at 20 GHz: 2.6, dielectric tangent: 0.0016
Tensile modulus: 0.4 GPa, strength: 16 MPa, elongation: 235%

[Example 2]
A polyamic acid solution was prepared by charging 28.05 g of BTDA (0.087 mol), 46.95 g of DDA2 (0.86 mol), 105 g of NMP, and 70 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 70 g of xylene was added to complete the imidization, preparing polyimide solution 4 (solid content: 30 wt %, Mw: 48,452, Mn: 23,399, Mw/Mn: 2.07).

Polyimide composition 4 and resin sheet 4 were prepared in the same manner as in Reference Example 1, except that the amount of N-12 was 1.269 g.

The various characteristics of the resin sheet 4 are as follows.
Dielectric constant at 5 GHz: 2.8, dielectric tangent: 0.0028
Dielectric constant at 10 GHz: 2.7, dielectric tangent: 0.0024
Dielectric constant at 20 GHz: 2.7, dielectric tangent: 0.0015
Tensile modulus: 0.6 GPa, strength: 24 MPa, elongation: 191%

[Example 3]
A polyamic acid solution was prepared by charging 33.73 g of BTDA (0.104 mol), 56.27 g of DDA2 (0.105 mol), 126 g of NMP, and 84 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 84 g of xylene was added to complete the imidization, preparing polyimide solution 5 (solid content: 30 wt %, Mw: 63,338, Mn: 29,207, Mw/Mn: 2.17).

Polyimide composition 5 and resin sheet 5 were prepared in the same manner as in Reference Example 1, except that the amount of N-12 was 1.517 g.

The various characteristics of the resin sheet 5 are as follows.
Dielectric constant at 5 GHz: 2.6, dielectric tangent: 0.0025
Dielectric constant at 10 GHz: 2.6, dielectric tangent: 0.0021
Dielectric constant at 20 GHz: 2.7, dielectric tangent: 0.0016
Tensile modulus: 0.4 GPa, strength: 20 MPa, elongation: 210%

[Example 4]
A polyamic acid solution was prepared by charging 33.63 g of BTDA (0.104 mol), 56.37 g of DDA2 (0.106 mol), 126 g of NMP, and 84 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 84 g of xylene was added to complete the imidization, preparing polyimide solution 6 (solid content: 30 wt %, Mw: 85,454, Mn: 30,797, Mw/Mn: 2.77).

Polyimide composition 6 and resin sheet 6 were prepared in the same manner as in Reference Example 1, except that the amount of N-12 was 1.517 g.

The various properties of the resin sheet 6 are as follows:
Dielectric constant at 5 GHz: 2.6, dielectric tangent: 0.0025
Dielectric constant at 10 GHz: 2.6, dielectric tangent: 0.0021
Dielectric constant at 20 GHz: 2.6, dielectric tangent: 0.0016
Tensile modulus: 0.4 GPa, strength: 15 MPa, elongation: 224%

[Example 5]
A polyamic acid solution was prepared by charging 55.88 g of BTDA (0.173 mol), 94.12 g of DDA1 (0.175 mol), 210 g of NMP, and 140 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 120 g of xylene was added to complete the imidization, preparing polyimide solution 7 (solid content: 30 wt %, Mw: 95,519, Mn: 30,544, Mw/Mn: 3.13).

Polyimide composition 7 and resin sheet 7 were prepared in the same manner as in Reference Example 1, except that the amount of N-12 was 2.523 g.

The various characteristics of the resin sheet 7 are as follows.
Dielectric constant at 5 GHz: 2.6, dielectric tangent: 0.0025
Dielectric constant at 10 GHz: 2.7, dielectric tangent: 0.0022
Dielectric constant at 20 GHz: 2.7, dielectric tangent: 0.0018
Tensile modulus: 0.6 GPa, strength: 24 MPa, elongation: 229%

The above results are summarized in Tables 1 and 2.

The above describes in detail an embodiment of the present invention for illustrative purposes, but the present invention is not limited to the above embodiment and various modifications are possible.

REFERENCE SIGNS LIST 10...substrate, 11...first substrate, 12...second substrate, 20...adhesive layer, 30, 33, 34...insulating resin layer, 31...first insulating resin layer, 32...second insulating resin layer, 41...first single-sided metal-clad laminate, 42...second single-sided metal-clad laminate, 50...wiring layer, M...metal layer, M1...first metal layer, M2...second metal layer, 100...laminated body, 101...three-layer metal-clad laminate, 102...bonded metal-clad laminate, 103...metal-clad laminate with adhesive layer, 200, 201, 202...circuit board, 203...multilayer circuit board

Claims (20)

A polyimide containing a tetracarboxylic acid residue derived from a tetracarboxylic acid anhydride component and a diamine residue derived from a diamine component, the polyimide satisfying the following conditions a to d:
a) containing 40 mol % or more of diamine residues derived from a dimer diamine composition mainly composed of a dimer diamine obtained by substituting two terminal carboxylic acid groups of a dimer acid with primary aminomethyl groups or amino groups, relative to the total diamine residues;
b) the weight average molecular weight (Mw) is in the range of 25,000 to 100,000;
c) a number average molecular weight (Mn) in the range of 15,000 to 32,000;
d) the ratio of Mw to Mn (Mw/Mn) is in the range of 1.8 to 3.4;
While satisfying the above,
The dimer diamine composition comprises the following components (a) to (c):
(a) dimer diamine;
(b) a monoamine compound obtained by substituting a terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group;
(c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the above-mentioned dimer diamine);
The content of the component (a) in the dimer diamine composition is 97.9 % by weight or more. The polyimide according to claim 1, wherein the area percentage of the chromatogram of the dimer diamine composition measured by gel permeation chromatography is 3% or less for the component (b). The polyimide according to claim 2, wherein the total area percentage of the (b) component and the (c) component in the chromatogram is 4% or less. Components (A) and (B) below;
(A) the polyimide according to claim 1, and (B) a metal salt of an organic phosphinic acid.
and wherein the weight ratio of the component (B) to the component (A) is within the range of 10 to 70% by weight. The polyimide of the component (A) is a polyimide having a ketone group in the molecule, and further comprises the following component (C):
(C) a crosslinking agent having a functional group that undergoes a nucleophilic addition reaction with the ketone group;
The polyimide composition according to claim 4, comprising: An adhesive film containing the polyimide according to claim 1. Components (A) and (B) below;
(A) the polyimide according to claim 1;
And,
(B) a metal salt of an organic phosphinic acid;
and wherein the weight ratio of the component (B) to the component (A) is within the range of 10 to 70% by weight. Components (A') and (B) below;
(A') a crosslinked polyimide having a crosslinked structure formed by a reaction between the polyimide according to claim 1 having a ketone group in the molecule and a crosslinking agent having a functional group which undergoes a nucleophilic addition reaction with the ketone group;
And,
(B) a metal salt of an organic phosphinic acid;
and wherein the weight ratio of the component (B) to the component (A') is within the range of 10 to 70% by weight. A laminate having a substrate and an adhesive layer laminated on at least one surface of the substrate,
A laminate, wherein the adhesive layer comprises the adhesive film according to any one of claims 6 to 8. A coverlay film having a coverlay film material layer and an adhesive layer laminated on the coverlay film material layer,
A coverlay film, characterized in that the adhesive layer is made of the adhesive film according to any one of claims 6 to 8. A resin-coated copper foil having an adhesive layer and a copper foil laminated thereon,
A resin-coated copper foil, characterized in that the adhesive layer is made of the adhesive film according to any one of claims 6 to 8. A metal-clad laminate having an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer,
9. A metal-clad laminate, wherein at least one of the insulating resin layers is made of the adhesive film according to claim 6. A metal-clad laminate having an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer,
A metal-clad laminate, wherein the adhesive layer comprises the adhesive film according to any one of claims 6 to 8. A first single-sided metal-clad laminate having a first metal layer and a first insulating resin layer laminated on at least one surface of the first metal layer;
a second single-sided metal-clad laminate having a second metal layer and a second insulating resin layer laminated on at least one surface of the second metal layer;
An adhesive layer is disposed so as to abut against the first insulating resin layer and the second insulating resin layer, and is laminated between the first single-sided metal-clad laminate and the second single-sided metal-clad laminate,
A metal-clad laminate, wherein the adhesive layer comprises the adhesive film according to any one of claims 6 to 8. A metal-clad laminate comprising a single-sided metal-clad laminate having an insulating resin layer and a metal layer laminated on one side of the insulating resin layer, and an adhesive layer laminated on the other side of the insulating resin layer, the adhesive layer being made of the adhesive film according to any one of claims 6 to 8. A circuit board obtained by wiring the metal layer of the metal-clad laminate according to any one of claims 12 to 15. A circuit board comprising: a first base material; a wiring layer laminated on at least one surface of the first base material; and an adhesive layer laminated on a surface of the first base material facing the wiring layer so as to cover the wiring layer,
A circuit board, wherein the adhesive layer is made of the adhesive film according to any one of claims 6 to 8. A circuit board comprising: a first base material; a wiring layer laminated on at least one surface of the first base material; an adhesive layer laminated on a surface of the first base material facing the wiring layer so as to cover the wiring layer; and a second base material laminated on a surface of the adhesive layer opposite to the first base material,
A circuit board, wherein the adhesive layer is made of the adhesive film according to any one of claims 6 to 8. A circuit board comprising: a first base material; an adhesive layer laminated on at least one surface of the first base material; a second base material laminated on a surface of the adhesive layer opposite to the first base material; and wiring layers laminated on each of the first base material and the second base material opposite to the adhesive layer,
A circuit board, wherein the adhesive layer is made of the adhesive film according to any one of claims 6 to 8. A multilayer circuit board comprising a laminate including a plurality of laminated insulating resin layers, and at least one wiring layer embedded in the laminate,
At least one of the plurality of insulating resin layers is formed of an adhesive layer having adhesiveness and covering the wiring layer,
A multilayer circuit board, wherein the adhesive layer is made of the adhesive film according to any one of claims 6 to 8.

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