TW201731918A - Polyimide, polyimide film, and flexible copper clad laminate - Google Patents

Abstract

A polyimide includes repeating units represented by the following formulas I and II:(I) (II) where the polyimide is a block copolymer or a random copolymer, Ar is derived from a tetravalent aromatic radical, D includes -(C6H4)- and -(C6H4)-O-(C6H4)-, E is a divalent triazole radical, and d and e respectively represent the mole percentage of the repeating units represented by the formulas I and II, where 5% ≤ e/d ≤ 10%.

Description

Polyimine, polyimide film and soft copper foil substrate

The present invention relates to a polyimide, a polyimide film, and a soft copper foil substrate, and more particularly to a polyimine polymer having a nitrogen-containing heterocycle, a polyimine comprising the polyimine A film and a soft copper foil substrate comprising the polyimide film.

As electronic products gradually move toward thin and light trends, the demand for flexible circuit boards has also increased significantly. In general, a flexible circuit board includes at least a flexible substrate and a conductive line attached to the flexible substrate. Since the conductive line has a specific layout design, it can transmit the electrical signal along a predetermined path to a predetermined area.

In the case where the flexible substrate is a polyimide substrate, the flexible circuit board manufacturing method may include the following steps: first, coating the polyaminic acid solution on the metal foil, followed by heating to make the polyaminic acid solution in the metal foil A dehydration reaction is carried out to form a polyimide film. Next, the metal foil is patterned to form the desired conductive trace pattern. In addition, an adhesive layer may be additionally coated on the metal foil before the coating of the polyaminic acid solution to enhance the adhesion of the subsequent polyimide film and the metal foil.

However, even if the above flexible circuit board and its manufacturing method have been widely used in the industry, there are still many technical defects. For example, when the metal foil is selected from a low-surface roughness and a thin-thickness rolled copper foil, the adhesive layer still does not impart good adhesion to the polyimide film and the copper foil, and the patterned flexible circuit board also The problem of curling occurs due to the presence of the adhesive layer.

Therefore, there is still a need to provide a polyimide polyimide polymer, a polyimide film, and a soft copper foil substrate to solve the drawbacks found in the prior art.

In view of the above, the present invention provides a polyimine film having a nitrogen-containing heterocyclic ring, a polyimine film including the polyimine, and a soft copper foil substrate including the polyimide film to solve The above-mentioned prior art is missing.

According to an embodiment of the present invention, there is provided a polyimine comprising a repeating unit represented by the following formula (I) and formula (II), wherein the repeating units are block-arranged or disorder-arranged: (I) (II)

among them,

Ar is derived from a tetravalent organic group containing an aromatic compound;

D series includes a phenylene and a phenylene ether group;

E is a divalent organic group including a triazole;

d and e represent the molar fraction of the repeating unit represented by the formula (I) and the formula (II), respectively, wherein 5% ≤ e / d ≤ 10%.

According to another embodiment of the present invention, there is provided a polyimide film comprising a repeating unit represented by the following formula (I) and formula (II), wherein the repeating units are block or disorderly arranged : (I) (II)

among them,

Ar is derived from a tetravalent organic group containing an aromatic compound;

D series includes a phenylene and a phenylene ether group;

E is a divalent organic group including a triazole;

d and e represent the molar fraction of the repeating unit represented by the formula (I) and the formula (II), respectively, wherein 5% ≤ e / d ≤ 10%.

According to still another embodiment of the present invention, there is provided a flexible copper foil substrate comprising a copper foil and a polyimide film directly contacting the copper foil, wherein the composition of the polyimide film comprises the following formula (I) and a repeating unit represented by the formula (II), which is a block arrangement or an disordered arrangement: (I) (II)

among them,

Ar is derived from a tetravalent organic group containing an aromatic compound;

D series includes a phenylene and a phenylene ether group;

E is a divalent organic group including a triazole;

d and e represent the molar fraction of the repeating unit represented by the formula (I) and the formula (II), respectively, wherein 5% ≤ e / d ≤ 10%.

According to the above embodiment, since the polyimine has a certain proportion of the nitrogen-containing hetero ring, an excellent adhesion between the corresponding polyimide film and the copper foil can be produced. In this case, even if an adhesive layer is not provided on the copper foil, the peel strength can be excellent between the polyimide film and the copper foil. Further, since the step of applying the adhesive layer can be omitted, in addition to simplifying the process, the patterned soft copper foil substrate does not cause curling.

In the following, the term "a certain value to another value" is used to describe a particular numerical range, which should be construed as covering any numerical value within the numerical range and the value defined by any numerical value within the numerical range. The singular value ranges as the exact values and the smaller numerical ranges are explicitly recited in the specification. Further, for the sake of brevity, the structure of each polymer or group hereinafter is sometimes represented by a skeleton formula, and carbon atoms, hydrogen atoms, and carbon-hydrogen bonds in the actual structure are omitted. However, where a particular atom or group of atoms is clearly depicted in the structural formula, the drawing is preferred.

According to an embodiment of the present invention, there is provided a polyimine copolymer, wherein the structure of the polyimine comprises a repeating unit represented by the following formula (I) and formula (II), wherein the repeating unit is Block arrangement or disordered arrangement: (I) (II)

among them,

Ar is derived from a tetravalent organic group containing an aromatic compound;

D series includes a phenylene and a phenylene ether group;

E is a divalent organic group including a triazole;

d and e represent the molar fraction of the repeating unit represented by the formula (I) and the formula (II), respectively, wherein 5% ≤ e / d ≤ 10%.

Ar in the above formula (I) and formula (II) is a residue other than two carboxylic anhydride groups (-(CO) ₂ O) in the tetracarboxylic dianhydride compound, and D and E are in addition to the diamine compound. A residue other than two amino groups (-NH ₂ ). Preferably, Ar may comprise a tetravalent biphenyl group and a tetravalent phenyl group, and the molar ratio between the two is preferably between about 5:1 and 4:1. Further, for the phenylene and phenylene ether groups represented by D, the molar ratio of the two is preferably between about 20:1 and 16:1.

The preparation method of the above polyimine copolymer is described in detail below. First, the diamine compound in the above embodiment is added to a solvent in a water bath (room temperature), mixed, and completely dissolved to form a mixed liquid of a diamine monomer. Among them, when the diamine compound is 3,5-diamino-1,2,4-triazole (DATA), p-phenylenediamine (PPD/PDA) and 4,4'-diaminodiphenyl ether (ODA), the total number of moles of DATA in the diamine monomer mixture is preferably between 5% and 10%, that is, 5% ≤ DATA / (PPD +). ODA) ≤ 10%, and the molar ratio of PPD and ODA is preferably between about 20:1 and 16:1.

Wherein, the solvent may be selected from the group consisting of hexamethylphosphoramide (HMPA), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (N- Highly polar aprotic solvent such as methyl-2-pyrrolidone, NMP), 1,3-dimethylimidazolinone (DMI), or m-cresol, but not limited herein.

It is to be noted that, in addition to the above-described diamine compound, it may be selected from the group consisting of, but not limited to, 4,4'-diaminobenzophenone and 3,5-diamine. a derivative of keto-1,2,4-triazole. These diamine compounds may be used singly or in a mixture of plural kinds. The above derivatives of DATA can be represented by the following structural formula:

Wherein the carbon numbers of R ₂ and R ₃ are independent of each other, and preferably each is an alkylene group having a carbon number of from 1 to 3. It should be noted that when the carbon number of R ₂ and R ₃ is higher than 3, the polyimine copolymer has a higher coefficient of thermal expansion, thereby lowering the adhesion between the polyimide and the copper foil. .

After the diamine monomer mixture is obtained by the above process, the previously mixed tetracarboxylic dianhydride monomer mixture can be added to the diamine monomer mixture in a water bath (room temperature) for condensation polymerization. After the reaction is carried out for 3 hours to 5 hours, the desired polyaminic acid solution can be formed. Wherein, when the tetracarboxylic dianhydride compound is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA), the tetracarboxylic dianhydride single The molar ratio of BPDA to PMDA in the bulk mixture is preferably between about 5:1 and 4:1. At this time, the solid content of the polyaminic acid solution is, for example, 15% to 20%.

In addition to the tetracarboxylic dianhydride compound of the above kind, it may also be selected from the group consisting of the following compounds, but is not limited thereto: 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane Diacetic anhydride (6FDA), 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4' - benzophenone tetracarboxylic dianhydride (BTDA), ethyltetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, 2, 2', 3, 3'- Benzophenone tetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2 - bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)ruthenic anhydride, 1,1- Bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 4,4- (p-phenylenedioxy)diphthalic acid dianhydride, 4,4'-(m-phenyldioxy)diphthalic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1, 4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10 - perylene tetracarboxylic dianhydride, 2,3,6,7- Terpene tetracarboxylic dianhydride and 1,2,7,8-phenanthrenetetracarboxylic dianhydride. These tetracarboxylic dianhydride compounds may be used singly or in a mixture of plural kinds.

Thereafter, the polyaminic acid solution was subjected to a dehydration reaction under a nitrogen atmosphere to form a polyimine as shown below. Here, for the description of symbols such as Ar, D, E, d, e, and e/d, reference may be made to the descriptions of the formulas (I) and (II) above.

In detail, the dehydration reaction may be performed by first baking the polyamic acid solution at a temperature of 130 ° C to 160 ° C for 5 minutes to 10 minutes without using a catalyst to remove the solvent. Thereafter, the temperature was raised to 320 ° C to 380 ° C, and the temperature was maintained for 20 minutes to 40 minutes to carry out a dehydration reaction. However, the invention is not limited thereto. In other embodiments, the dehydration reaction can also be carried out using a catalyst.

According to another embodiment of the present invention, there is provided a polyimide film comprising a polyimine copolymer as described above. Referring to the foregoing method for producing a polyamidene copolymer, the method for producing a polyimide film comprises applying a polyaminic acid solution to a substrate through a coating process after forming a polyamic acid solution. And then subjected to a dehydration reaction. Wherein, the coating process may be a knife coating method, a spin coating method or other suitable coating method, and the substrate may be a copper foil or other suitable metal foil. The dehydration reaction may be performed, for example, by baking the polyamic acid solution at 130 ° C to 160 ° C for 5 minutes to 10 minutes to remove the solvent, and then raising the temperature to 320 ° C to 380 ° C and holding the temperature for 20 minutes. Up to 40 minutes to carry out the dehydration reaction. Further, the polyimide film has a thickness of between about 12 μm and 22 μm.

According to still another embodiment of the present invention, there is provided a flexible copper foil substrate comprising a copper foil and the aforementioned polyimide film. Among them, the polyimide film is a soft substrate in a flexible copper foil substrate, and the copper foil may be an electrolytic copper foil, a rolled copper foil or other suitable copper foil having a non-specific thickness. Referring to the foregoing method for manufacturing a polyimide film, the method for producing a flexible copper foil substrate may include applying a polyaminic acid solution to a copper foil through a coating process, and then performing a dehydration reaction to copper. A polyimide film is formed on the foil.

According to each of the above embodiments, a polyimine copolymer, a polyimide film, and a soft copper foil substrate are provided, wherein the polyamidene copolymer has a divalent organic group of a triazole, which can be produced with copper. N-Cu bonding, and the ratio between different monomers and the ratio between different repeating units are within a certain interval, so the polyimine copolymer, the corresponding polyimine film and the corresponding soft copper In addition to the conventional physical and chemical properties, the foil substrate can also have excellent peel strength with copper foil without applying an adhesive layer.

Embodiments of the present invention are described in further detail below in order to enable those of ordinary skill in the art to practice the invention. It is to be noted that the following examples are merely illustrative and should not be construed as limiting the invention. That is, the materials and materials used in the respective embodiments, the processing flow, and the like can be appropriately changed without departing from the scope of the invention.

The following is a list of abbreviations for each compound in the following examples and comparative examples and their source information:

ODA: 4,4'-diaminodiphenyl ether, available from JFE Chemical Co., Ltd.

PDA: p-phenylenediamine, purchased from Eastcom Chemical Company.

DATA: 3,5-Diamino-1,2,4-triazole, purchased from Eastcom Chemical Company.

PMDA: pyromellitic dianhydride, purchased from JFE Chemical Co., Ltd.

BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride, available from JFE Chemical Co., Ltd.

NMP: N-methyl-2-pyrrolidone, available from TEDIA Corporation.

Copper foil: purchased from Mitsui Chemicals.

Example 1

1.26 g (0.006 mol, 5 mol%) of 4,4'-diaminodiphenyl ether (ODA) in a water bath (room temperature) using N-methyl-2-pyrrolidone (NMP) as solvent. 12.24 g (0.113 mol, 90 mol%) of p-phenylenediamine (PDA) and 5 g (0.05 m, 5 mol%) of 3,5-diamino-1,2,4-triazole (DATA) Dissolved in 200 g of NMP and continuously stirred for 2 hours to form a mixed solution of diamine monomers. After complete dissolution, a uniform 6.63 g (0.003 mol, 18 mol%) of pyromellitic dianhydride (PMDA) and 40.77 g (0.138 mol, 82 mol%) of 3,3' were premixed in a water bath. 4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to the above mixed solution of the diamine monomer in three portions. It should be noted that in the present embodiment, the molar ratio of the diamine monomer to the dianhydride monomer is preferably about 1:1, but is not limited thereto. Next, the mixed solution having the diamine monomer and the dianhydride monomer was continuously stirred, and after 3 hours of reaction, a polyamine solution having a solid content of 20% was obtained. Thereafter, 20 ml of the polyaminic acid solution was coated on a rolled copper foil having a thickness of 1/3 oz (oz) using a knife coating method, followed by baking at 150 ° C for 10 minutes to remove NMP solvent. Subsequently, the copper foil coated with the polyaminic acid solution was placed in an oxygen-free atmosphere at 350 ° C for 30 minutes to carry out a dehydration reaction, and a polyimide film of Example 1 disposed on a copper foil was obtained. Finally, the copper foil was removed by an etching process to obtain the polyimide film of Example 1, wherein the thickness was measured with a low force meter, and the thickness was measured to be between about 12 μm and 22 μm.

Example 2

The manufacturing procedure of Example 2 was substantially the same as the manufacturing procedure of Example 1, but the molar percentage of each monomer employed in Example 2 is shown in Table 1.

Comparative example

The manufacturing procedure of the comparative example was substantially the same as that of the manufacturing procedure of Example 1, but the molar percentage of each monomer used in the comparative example is shown in Table 1.

Various physical property measurement methods for the aforementioned polyimide film and soft copper foil substrate will be described in detail below, and the results of the measurement are shown in Table 1. Each measurement item includes: decomposition temperature (Td), coefficient of thermal expansion (CTE), tensile strength, elongation, tensile modulus (tensile) Elastic modulus), peel strength, solder heat resistance, and measurement of warpage after copper foil etching.

<Measurement of Thermal Cracking Temperature>

The thermal cracking temperature was tested according to the IPC-TM-650 2.4.24.6 method. First, 0.5 to 0.8 g of the polyimide films of Examples 1, 2 and Comparative Examples were weighed separately to obtain a test film. Next, using a thermogravimetric loss analyzer (manufactured by Seiko Instrument Inc., the device name is EXSTAR 6000), the temperature increase rate was set to 10 ° C / min, and the membranes were taken from 30 ° C under a nitrogen atmosphere. The temperature was measured to a temperature of 600 ° C, and the temperature measured when the film was lost by 5% by weight was taken as the thermal cracking temperature. In the industry, the thermal decomposition temperature of the polyimide film is generally at least 450 ° C, and the larger the value, the better the thermal stability of the polyimide film.

<Measurement of Thermal Expansion Coefficient>

First, the polyimide films of Examples 1 and 2 and Comparative Examples were each formed into a film having a width of 2 mm × 30 mm. Next, using a thermomechanical analyzer (manufactured by Seiko Instrument Inc., the device name is EXSTAR 6000), the temperature increase rate was set to 10 ° C / min, and the membranes were heated from 30 ° C under a nitrogen atmosphere. To 450 ° C, an average value of the dimensional change amount between 50 ° C and 300 ° C was determined to obtain a coefficient of thermal expansion. In general, the coefficient of thermal expansion of the copper foil is 17 ppm/° C., and the coefficient of thermal expansion of 17 ± 5 ppm / ° C is considered to be similar to the coefficient of thermal expansion of the copper foil.

<Measurement of tensile strength>

Tensile strength was tested according to the IPC-TM-650 2.4.19.C method. First, the polyimide films of Examples 1, 2 and Comparative Examples were each formed into a film having a width of 76.20 mm × 12.70 mm. Next, using a universal testing machine (manufactured by Shimadzu Scientific Instruments Co., Ltd. (SHIMADZU), the equipment name is AG-1S), the tensile speed was set to 50.8 mm/min, and the relationship between the tensile force and the elongation of the polyimide film was continuously recorded. Until the polyimide film breaks. The tensile strength of the polyimide film can be obtained by dividing the tensile force of the polyimide film when it is broken by the cross-sectional area of the original sample.

<Tensile elongation>

The tensile elongation was tested in accordance with the IPC-TM-650 2.4.19.C method. First, the polyimide films of Examples 1, 2 and Comparative Examples were each formed into a film having a width of 76.20 mm × 12.70 mm. Next, using a universal testing machine (manufactured by Shimadzu Scientific Instruments Co., Ltd. (SHIMADZU), the equipment name is AG-1S), the tensile speed was set to 50.8 mm/min, and the relationship between the tensile force and the elongation of the polyimide film was continuously recorded. Until the polyimide film breaks. The tensile elongation can be obtained by subtracting the original length of the polyimide film from the length of the polyimide film and dividing it by the original length of the polyimide film.

<Tensile modulus of elasticity>

The tensile modulus of elasticity was tested in accordance with the IPC-TM-650 2.4.19.C method. First, the polyimide films of Examples 1, 2 and Comparative Examples were each formed into a film having a width of 76.20 mm × 12.70 mm. Next, using a universal testing machine (manufactured by Shimadzu Scientific Instruments Co., Ltd. (SHIMADZU), the equipment name is AG-1S), the tensile speed was set to 50.8 mm/min, and the relationship between the tensile force and the elongation of the polyimide film was continuously recorded. Until the polyimide film breaks. The tensile elastic modulus is determined according to the tensile force and the corresponding elongation before the polyimine film is broken.

<Measurement of Peel Strength>

The peel strength was tested in accordance with the IPC-TM-650 2.4.9 method. First, the polyimide film disposed on the copper foil of Examples 1, 2 and Comparative Example was cut together with a copper foil into a test sample having a width of 3.2 mm. Next, using a universal testing machine (manufactured by Shimadzu Scientific Instruments Co., Ltd. (SHIMADZU), the device name is AG-1S), the stretching speed was set to 50.8 mm/min, and the test samples were stretched to a tensile length of 30 mm. The tensile force value is continuously recorded to determine the peel strength at this time. It should be noted that the greater the adhesion between the polyimide film and the copper foil, the less likely the interface between the two is to be damaged by external force. That is, the higher the value of the peel strength shown in Table 1, the greater the adhesion force between the polyimide film and the copper foil.

<Measurement of solder heat resistance>

The solder heat resistance was tested according to the IPC-TM-650 2.4.13 method, and the soft copper foil substrate was cut into a 5 cm × 5 cm sample and floated on the surface of the molten solder at 300 ° C for 10-30 seconds, and Observe whether the soft copper foil substrate is layered.

<Measurement of warpage after etching of copper foil>

The warpage after etching of the copper foil was tested in accordance with the IPC-TM-650 2.4.22 method. Cut the soft copper foil substrate into a 25cm×25cm sample, place the sample on a straight surface, measure the distance between the four corners with a ruler, add the four values, and divide it to obtain the curl value to judge the warpage. In the case, less than 1 cm is considered to be flat.

Table 1

^* : mol% is based on the total number of moles of ODA, PDA and DATA.

^** : mol% is based on the total number of moles of PMDA and BPDA.

As can be seen from Table 1, the peel strengths of the polyimide films of Examples 1 and 2 were all greater than 0.6 kgf/cm, and were at least 40% higher than the peel strength of the polyimide film in the comparative example. The polyimide film of Examples 1 and 2 had a good adhesion to the copper foil. In addition, since polyphenyleneimine is synthesized by using p-phenylenediamine (PDA) as the main synthetic monomer in the diamine solution, the corresponding polyimine may have a thermal expansion coefficient similar to that of the copper foil, and has Higher tensile stress and tensile modulus of elasticity.

According to the above embodiment, since the polyimine has a certain proportion of the nitrogen-containing hetero ring, an excellent adhesion between the corresponding polyimide film and the copper foil can be produced. In this case, even if an adhesive layer is not provided on the copper foil, the peel strength can be excellent between the polyimide film and the copper foil. Further, since the step of applying the adhesive layer can be omitted, in addition to simplifying the process, the patterned soft copper foil substrate does not cause curling. The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

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Claims (18)

A polyimine comprising a repeating unit represented by the following formula (I) and formula (II), wherein the repeating units are block-arranged or disorder-arranged: (I) (II) wherein, the Ar system is derived from a tetravalent organic group containing an aromatic compound; the D system includes a phenylene and a phenylene ether group; the E system is a divalent organic group including a triazole; and d and e respectively The molar fraction of the repeating unit represented by the formula (I) and the formula (II), wherein 5% ≤ e / d ≤ 10%. The polyimine according to claim 1, wherein the Ar system comprises a tetravalent biphenyl group and a tetravalent phenyl group. The polyimine according to claim 2, wherein the molar ratio of the tetravalent biphenyl group and the tetravalent phenyl group is between about 5:1 and 4:1. The polyimine of claim 1, wherein the molar ratio of the phenyl and phenylene groups is between about 20:1 and 16:1. The polyimine according to claim 1, wherein the polyimine is obtained by polymerization of a monomer solution, wherein the composition of the monomer solution comprises 3, 3', 4, 4'- Biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), p-phenylenediamine (PPD/PDA), 4,4'-diaminodiphenyl ether (ODA), and 3, 5-Diamino-1,2,4-triazole (DATA). A polyimine film comprising a polyimine, wherein the polyimine comprises repeating units represented by the following formula (I) and formula (II), wherein the repeating units are block arrangements or Unordered arrangement: (I) (II) wherein, the Ar system is derived from a tetravalent organic group containing an aromatic compound; the D system includes a phenylene and a phenylene ether group; the E system is a divalent organic group including a triazole; and d and e respectively The molar fraction of the repeating unit represented by the formula (I) and the formula (II), wherein 5% ≤ e / d ≤ 10%. The polyimine film according to claim 6, wherein the Ar system comprises a tetravalent biphenyl group and a tetravalent phenyl group. The polyimine film according to claim 7, wherein the molar ratio of the tetravalent biphenyl group and the tetravalent phenyl group is between about 5:1 and 4:1. The polyimine film according to claim 6, wherein the molar ratio of the phenyl and phenylene ether groups is between about 20:1 and 16:1. The polyimine film according to claim 6, wherein the polyimine is obtained by polymerization of a monomer solution, wherein the composition of the monomer solution comprises 3, 3', 4, 4' -biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), p-phenylenediamine (PPD/PDA), 4,4'-diaminodiphenyl ether (ODA), and , 5-diamino-1,2,4-triazole (DATA). The polyimine film according to claim 6, wherein the polyimide film has a thickness of from 12 mm to 22 mm. A soft copper foil substrate comprising: a copper foil; and a polyimide film directly contacting the copper foil, wherein the composition of the polyimide film comprises a polyimine, wherein the polyimide The amine includes repeating units represented by the following formula (I) and formula (II), which are block-arranged or disorder-arranged: (I) (II) wherein, the Ar system is derived from a tetravalent organic group containing an aromatic compound; the D system includes a phenylene and a phenylene ether group; the E system is a divalent organic group including a triazole; and d and e respectively The molar fraction of the repeating unit represented by the formula (I) and the formula (II), wherein 5% ≤ e / d ≤ 10%. The soft copper foil substrate according to claim 12, wherein the Ar system comprises a tetravalent biphenyl group and a tetravalent phenyl group. The soft copper foil substrate according to claim 13, wherein the molar ratio of the tetravalent biphenyl group and the tetravalent phenyl group is between about 5:1 and 4:1. The soft copper foil substrate according to claim 12, wherein the molar ratio of the phenyl and phenylene ether groups is between about 20:1 and 16:1. The soft copper foil substrate according to claim 12, wherein the polyamidene is obtained by polymerization of a monomer solution, wherein the composition of the monomer solution comprises 3, 3', 4, 4'- Biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), p-phenylenediamine (PPD/PDA), 4,4'-diaminodiphenyl ether (ODA), and 3, 5-Diamino-1,2,4-triazole (DATA). The soft copper foil substrate according to claim 12, wherein no adhesive layer is provided between the copper foil and the polyimide film. The soft copper foil substrate of claim 12, wherein the peel strength between the polyimide film and the copper foil is between 0.4 kgf/cm and 0.9 kgf/cm.