Soluble thermoplastic polyimide resin, method for producing the same, coating, composite film, and flexible copper clad laminate

Abstract

The application provides a soluble thermoplastic polyimide resin, a preparation method thereof, a coating, a composite film and a flexible copper-clad plate. The application concentrates bulky functional groups in X segments and enters the molecular main chain in a block structure, so that the molecular chain spacing is further increased, the solvent molecules enter the inside of the entangled molecular chain group, and the solubility is increased. Moreover, while the solubility is increased, the block structure can reduce the proportion of the bulky functional group monomers and reduce the influence of the bulky functional group monomers on the flexibility of the molecular main chain. Thus, the polyimide resin of the application still has a low glass transition temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to a soluble thermoplastic polyimide resin and a preparation method thereof, a coating, a composite film, and a flexible copper-clad plate, and belongs to the field of polyimides. BACKGROUND

[0002] The flexible copper-clad plate (FCCL) is the substrate of a circuit board. Compared with the traditional FCCL with adhesive, the FCCL without adhesive has the advantages of high heat resistance, high dimensional stability, high weather resistance, long service life, etc., and has a broader market prospect and application value in consumer electronic products such as mobile phones, tablet computers, notebook computers, and automobiles.

[0003] The FCCL without adhesive mainly has the following three production methods: coating method, compression method, and sputtering plating method. The sputtering plating method forms a copper foil layer with a certain thickness on both sides of a high-strength polyimide film through seed sputtering and electroplating thickening process. This production method is complex and has high cost, and the obtained copper foil layer is relatively thin, which is generally applied to special circuit boards such as COF. The coating method coats a polyamide acid solution on the surface of a copper foil, generates a polyimide thin layer on the surface of the copper foil through solvent evaporation and high-temperature imidization process, and obtains a no-adhesive single-sided board product. When the coating is a thermoplastic polyimide (TPI), a no-adhesive double-sided board product can be further obtained through the compression process. The compression method is suitable for the production of no-adhesive double-sided board. First, a thermoplastic polyamide acid solution is coated on both sides of a polyimide film (PI film), and then a thermoplastic polyimide composite film (TPI composite film) is prepared through a solvent evaporation process and a high-temperature imidization process. Then, a layer of copper foil is hot-pressed on both sides of the TPI composite film at high temperature to obtain a no-adhesive double-sided board product.

[0004] In the current production process, the precursor of TPI, i.e., a polyamide acid (PAA) solution, is coated on the surface of the PI film. After coating, in addition to the evaporation of the solvent, a further high-temperature imidization process at 300-400℃ is required. This process has high requirements for the performance of the PI film, which needs to maintain high dimensional stability and high mechanical strength after high-temperature treatment at 300-400℃. Moreover, the process temperature reaches 300-400℃, which puts high requirements on the precision and stability of the equipment. In the high-temperature process, an inert gas such as nitrogen is required to protect the TPI composite film from attack by oxygen in the air, which will lead to an increase in equipment cost and manufacturing cost. Therefore, it is necessary to provide a new preparation method of TPI composite film to improve the above problems. SUMMARY

[0005] To solve the above technical problems, the purpose of the present application is to provide a soluble thermoplastic polyimide resin and a preparation method thereof, a coating, a composite film, and a flexible copper-clad plate, which has strong solubility and low glass transition temperature.

[0006] To achieve the above object, the present application provides a soluble thermoplastic polyimide resin, the molecular main chain of which comprises a molecular segment L and a molecular segment X; the molecular segment L has a molecular structure shown in Formula I, and the molecular segment X has a molecular structure shown in Formula II:

[0007]

[0008] In Formula I, 10≤m≤55;

[0009] Ar1 is selected from a single benzene ring with 6-27 carbon atoms, a tetravalent aromatic group connected by a covalent group with multiple benzene rings, and / or a tetravalent cycloalkane group with 4-6 carbon atoms;

[0010] B1 is selected from one or a combination of two or more of a single benzene ring with 6-27 carbon atoms, a divalent aromatic group connected by a covalent group with multiple benzene rings, a divalent cycloalkane group with 4-6 carbon atoms, and a divalent aliphatic group with 5-7 carbon atoms;

[0011] In Formula II, 3≤n≤10;

[0012] Ar2 is selected from a tetravalent aromatic group containing fluorine, and / or a tetravalent aromatic group containing a fluorene group;

[0013] B2 is selected from 、 、 、 、 one or a combination of two or more thereof.

[0014] The present application concentrates bulky functional groups in the X segment and enters the molecular main chain in a block structure, which can further increase the molecular chain spacing, enable solvent molecules to enter the inside of the entangled molecular chain group, and achieve the effect of increasing solubility. Moreover, while enhancing solubility, the block structure can reduce the proportion of bulky functional group monomers and reduce their impact on the flexibility of the molecular main chain. Thus, the polyimide resin of the present application still has a relatively low glass transition temperature.

[0015] The soluble thermoplastic polyimide resin of the present application has strong solubility and low glass transition temperature. After subsequent dissolution, it can be coated on the surface of a PI film, and a TPI composite film can be obtained by drying the solvent. It has relatively low requirements for the performance of the PI film, and does not require the heat resistance of equipment and inert gas protection. The present application avoids the high-temperature imidization process, effectively reduces the cost of raw materials, equipment and process, reduces the complexity of operation, and improves the production applicability.

[0016] Further, Ar1 is selected from 、 , , , one or more combinations of the above; L1is selected from , , , , , , one or more combinations of the above; and , , the molar ratio in Ar1is 50-100%.

[0017] The molecular chain segment L in the block structure of the soluble thermoplastic polyimide resin of the present application contains high-flexibility functional groups and does not contain bulky functional groups, which further increases the flexibility of the molecular main chain, reduces the glass transition temperature of the polyimide, and makes the polyimide have better high-temperature melt bonding ability.

[0018] Further, B1is selected from , , , , , , one or more combinations of the above; L2, L3, and L4are each independently selected from a single bond, , , , one or more combinations of the above.

[0019] Further, Ar2is selected from , , , one or more combinations of the above.

[0020] Further, Ar1is selected from , , , , , , , , , , one or more combinations of the above.

[0021] Further, B1is selected from , , , , , 、 、 、 、 、 、 、 、 、 、 one or more combinations of the above.

[0022] Further, the molecular segment L and the molecular segment X are arranged alternately, and the total polymerization degree of the molecular segment L and the molecular segment X is 100-650. In the preparation, the X segment is prepared first, and the X segment is anhydride-terminated, so that the X-X connection mode does not exist, and the anhydride group at the end of the X segment can only be connected to the L segment to form an alternating arrangement.

[0023] Further, the number of polymerization units of the molecular segment L accounts for 70-90% of the total number of polymerization units of the molecular chain of the soluble thermoplastic polyimide resin.

[0024] Further, the weight of the molecular segment L accounts for 60-90% of the total weight of the molecular chain of the soluble thermoplastic polyimide resin.

[0025] Further, the solubility of the soluble thermoplastic polyimide resin in a strong polar solvent is more than 10 g / 100 g of the strong polar solvent; and the strong polar solvent is selected from one or more combinations of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, γ-butyrolactone, m-cresol, dichloromethane, trichloromethane, and tetrachloromethane.

[0026] Further, the glass transition temperature of the soluble thermoplastic polyimide resin is 220-290℃; and the thermal decomposition temperature of the soluble thermoplastic polyimide resin is ≥ 450℃.

[0027] The application further provides a preparation method of the soluble thermoplastic polyimide resin as described above, which comprises: polymerizing a diamine compound N2 and a dianhydride compound G2 to form a molecular segment X, and then adding a diamine compound N1 and a dianhydride compound G1 to obtain the soluble thermoplastic polyimide resin; wherein the dianhydride compound G2 is a dianhydride having an Ar2 residue; the diamine compound N2 is a diamine having a B2 residue; the dianhydride compound G1 is a dianhydride having an Ar1 residue; and the diamine compound N1 is a diamine having a B1 residue.

[0028] In some optional embodiments, the preparation method of the soluble thermoplastic polyimide resin comprises the following steps:

[0029] adding a dianhydride compound G2 to the solution containing the diamine compound N2 (the solvent can be selected from one or more of N-methylpyrrolidone, γ-butyrolactone, m-cresol, or a combination thereof) to perform a first polymerization reaction to obtain a first product system (solid content of 5-10%);

[0030] removing water generated in the first product system to obtain a second product system;

[0031] adding a diamine compound N1 and a dianhydride compound G1 to the second product system to perform a second polymerization reaction to obtain a third product system (solid content of 10-20%);

[0032] removing water generated in the third product system to obtain a fourth product system;

[0033] precipitating a soluble thermoplastic polyimide resin from the fourth product system.

[0034] In some optional embodiments, the dianhydride compound G2 is selected from one or more of hexafluoro dianhydride 6FDA, bisphenol A type diether dianhydride BPAFDA, 9,9-bis(trifluoromethyl)-xanthene tetracarboxylic dianhydride 6FCDA, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride BPAF, or a combination thereof.

[0035] The dianhydride compound G1 is selected from one or more of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride s-ODPA, 3,3',4,4'-benzophenone tetracarboxylic dianhydride BTDA, bisphenol A type diether dianhydride BPADA, pyromellitic dianhydride PMDA, 3,3',4,4'-biphenyl tetracarboxylic dianhydride s-BPDA, 3,3',4,4'-diphenyl isopropyl tetracarboxylic dianhydride IBPDA, 4,4'-p-phenylenedioxybisphthalic anhydride HQDA, p-phenylene-bisbenzotriacid dianhydride TAHQ, 3,3',4,4'-diphenyl methylene tetracarboxylic dianhydride MDPA, 1,2,3,4-cyclobutane tetracarboxylic dianhydride CBDA, 1,2,4,5-cyclohexane tetracarboxylic dianhydride HPMDA, or a combination thereof.

[0036] The diamine compound N2 is selected from one or more of 1,1-bis(4-aminophenyl)cyclohexane CHPDA, 1,1-bis(4-hydroxy-3-aminophenyl)cyclohexane CHPHDA, 9,9-bis(4-aminophenyl)fluorene FDA, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene FDA-OH, 9,9-bis(3-fluoro-4-aminophenyl)fluorene FDA-F, or a combination thereof.

[0037] The diamine compound N1 is selected from one or more than two of p-phenylenediamine (p-PDA), 4,4'-oxydianiline (4,4'-ODA), 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl (m-TD), 4,4'-diamino-2,2'-bistrifluoromethyl biphenyl (TFMB), 4,4'-diaminobenzanilide (4,4'-DABA), m-phenylenediamine (m-PDA), 3,4'-oxydianiline (3,4'-ODA), 4,4'-methylenedianiline (4,4'-MDA), 4,4'-diaminobenzophenone (4,4'-DAT), 4,4'-diaminodiphenyl sulfone (4,4'-DDS), 4,4'-bis(3-aminophenoxy) diphenyl sulfone (BAPS-M), 1,3-bis(4'-aminophenoxy) benzene (TPE-R), 1,3-bis(3'-aminophenoxy) benzene (APB), 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 1,4-cyclohexanediamine (1,4-CHDA), and 1,6-hexanediamine (1,6-HDA).

[0038] Further, the temperature of the first polymerization reaction and the second polymerization reaction is independently 5-45°C, and the time of the first polymerization reaction and the second polymerization reaction is independently 4-24h.

[0039] In some alternative embodiments, azeotropic water-carrying agent is used to remove the water generated in the product system. Specifically, the following steps are included: adding azeotropic water-carrying agent into the product system, the amount of the azeotropic water-carrying agent is 10-20% of the weight of the product system; then heating the product system to 160-190°C, and stirring for 2-8h to carry out the water generated in the reaction with the azeotropic water-carrying agent; and then evaporating and removing the azeotropic water-carrying agent from the solution at the same temperature. The azeotropic water-carrying agent is selected from toluene and / or xylene.

[0040] In some alternative embodiments, the precipitation includes the following steps: cooling the product system to below 100°C, adding a precipitation solvent to obtain a solid precipitate; filtering the solid precipitate, and washing it sufficiently with a washing solvent, and then drying it sufficiently at 150-250°C to obtain the soluble thermoplastic polyimide resin. The precipitation solvent and the washing solvent are independently selected from one or more than two of water, methanol, ethanol, and acetone.

[0041] The present application also provides a thermoplastic polyimide coating, which comprises a strong polar solvent and the soluble thermoplastic polyimide resin as described above.

[0042] Further, the solid content of the thermoplastic polyimide coating is 8-20%.

[0043] Furthermore, the highly polar solvent is selected from one or more combinations of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, γ-butyrolactone, m-cresol, dichloromethane, chloroform, and tetrachloromethane.

[0044] The present invention also provides a thermoplastic polyimide composite film, which includes a polyimide film having a first surface and a second surface opposite to each other; a first coating and a second coating are respectively disposed on the first surface and the second surface, the first coating and the second coating being obtained by coating and drying the aforementioned coatings respectively.

[0045] In some alternative embodiments, a coating machine or spin coater can be used to coat the surface of the polyimide film to obtain a liquid film of a certain thickness, then evaporate most of the solvent at 80~150°C, and finally dry it thoroughly at 200~250°C to obtain a thermoplastic polyimide composite film.

[0046] The present invention also provides a flexible copper-clad laminate, comprising a first copper foil, the aforementioned thermoplastic polyimide composite film, and a second copper foil stacked sequentially. For the reasons described above, the coating exhibits superior adhesion strength to the copper foil and the PI film substrate. Attached Figure Description

[0047] Figure 1 The diagram shows the structural schematic of the s-TPI resin obtained in Examples 1-3 of the present invention;

[0048] Figure 2 The diagram shows the structural schematics of the s-TPI resins obtained in Examples 4-6 of this invention;

[0049] Figure 3 The diagram shows the structural schematic of the s-TPI resin obtained in Examples 7-9 of this invention;

[0050] Figure 4 The diagram shows the structural schematics of the s-TPI resins obtained in Examples 10-12 of this invention;

[0051] Figure 5 The diagram shows the structural schematic of the s-TPI resin obtained in Examples 13-15 of the present invention;

[0052] Figure 6 The diagram shows the structural schematic of the s-TPI resin obtained in Examples 16-18 of this invention;

[0053] Figure 7 The diagram shows the structural schematics of the s-TPI resins obtained in Examples 19-22 of this invention;

[0054] Figure 8Structure diagrams of s-TPI resins obtained in Examples 23-26 of the present application are shown.

[0055] Figure 9 Structure diagrams of s-TPI resins obtained in Examples 27-30 of the present application are shown.

[0056] Figure 10 Structure diagrams of s-TPI resins obtained in Examples 31-33 of the present application are shown.

[0057] Figure 11 Structure diagrams of s-TPI resins obtained in Comparative Examples 1-4 are shown.

[0058] Figure 12 Structure diagrams of s-TPI resins obtained in Comparative Examples 5-7 are shown. DETAILED DESCRIPTION

[0059] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application are described in detail as follows, but it should not be understood as a limitation on the implementable scope of the present application. The raw materials used in the examples and comparative examples of the present application are shown in Table 1 as follows:

[0060] Table 1 above

[0061]

[0062] Table 1 above

[0063]

[0064] Table 1 above

[0065]

[0066] Example 1

[0067] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0068] (1) Preparation of X segment polyimide resin solution. Under a nitrogen atmosphere, 1.852 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 3.148 g of 6FDA was added to the solution, and the reaction was stirred for 8 h to obtain a polyamic acid solution. 15.0 g of toluene was added to the polyamic acid solution, and the polyamic acid solution was heated to 180°C and stirred for 4 h. Then, the toluene was removed from the solution by evaporation at 180°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0069] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 6.262 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and controlling the temperature of the solution to be 25°C. 6.178 g of s-ODPA was added into the solution and stirred for 8 h to obtain a soluble thermoplastic polyamide acid solution.

[0070] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 180°C and stirred for 4 h. Then, the toluene was removed from the solution by evaporation at 180°C. The solution was cooled to 30°C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 200°C to obtain s-TPI resin.

[0071] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution with a solid content of 18%. A coating machine was used to coat a liquid film with a thickness of about 30 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 120°C. A liquid film with a thickness of about 30 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 120°C. Then, the TPI composite film was obtained by drying at 220°C.

[0072] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer. The double-sided FCCL sample was obtained by pressing in a high-temperature flat press at 350°C for 1 min.

[0073] Example 2

[0074] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0075] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 1.976 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring and controlling the temperature of the solution to be 25°C. 3.024 g of 6FDA was added into the solution and stirred for 8 h to obtain a polyamide acid solution. 15.0 g of toluene was added into the polyamide acid solution and the polyamide acid solution was heated to 180°C and stirred for 4 h. Then, the toluene was removed from the solution by evaporation at 180°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0076] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 4.512 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 25 °C. 4.502 g of s-ODPA was added into the solution and stirred for 8 h to obtain a soluble thermoplastic polyamide acid solution.

[0077] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 180 °C and stirred for 4 h. Then, the toluene was removed from the solution by evaporation at 180 °C. The solution was cooled to 30 °C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 200 °C to obtain s-TPI resin.

[0078] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution with a solid content of 18%. A coating machine was used to coat a liquid film with a thickness of about 30 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 120 °C. A liquid film with a thickness of about 30 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 120 °C. Then, the TPI composite film was obtained by drying at 220 °C.

[0079] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and then the copper foil was pressed for 1 min at a high temperature of 350 °C on a flat plate press to obtain a double-sided FCCL sample.

[0080] Example 3

[0081] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0082] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 2.054 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring and the temperature of the solution was controlled at 45 °C. 2.946 g of 6FDA was added into the solution and stirred for 4 h to obtain a polyamide acid solution. 15.0 g of toluene was added into the polyamide acid solution and the polyamide acid solution was heated to 160 °C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160 °C to obtain an anhydride-terminated X segment polyimide resin solution.

[0083] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 4.425 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and controlling the temperature of the solution at 45 °C. 4.533 g of s-ODPA was added into the solution and stirred for 4 h to obtain a soluble thermoplastic polyamide acid solution.

[0084] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 160 °C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160 °C. The solution was cooled to 30 °C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 200 °C to obtain s-TPI resin.

[0085] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution with a solid content of 18%. A coating machine was used to coat a liquid film with a thickness of about 30 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 150 °C. A liquid film with a thickness of about 30 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 150 °C. Then, the TPI composite film was obtained by drying at 250 °C.

[0086] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer. The double-sided FCCL sample was obtained by pressing for 0.5 min at a high temperature of 370 °C on a flat pressing machine.

[0087] Example 4

[0088] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0089] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 2.081 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring and controlling the temperature of the solution at 45 °C. 2.919 g of 6FDA was added into the solution and stirred for 4 h to obtain a polyamide acid solution. 15.0 g of toluene was added into the polyamide acid solution and the polyamide acid solution was heated to 160 °C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160 °C to obtain an anhydride-terminated X segment polyimide resin solution.

[0090] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 4.456 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 45°C. 4.610 g of s-ODPA was added into the solution and stirred for 4 h to obtain a soluble thermoplastic polyamide acid solution.

[0091] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 160°C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160°C. The solution was cooled to 30°C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 200°C to obtain the s-TPI resin.

[0092] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution with a solid content of 18%. A coating machine was used to coat a liquid film with a thickness of about 30 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 150°C. A liquid film with a thickness of about 30 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 150°C. Then, the TPI composite film was obtained by drying at 250°C.

[0093] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer. The double-sided FCCL sample was obtained by pressing at a high temperature of 370°C for 0.5 min on a flat pressing machine.

[0094] Example 5

[0095] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0096] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 1.976 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 5°C. 3.024 g of 6FDA was added into the solution and stirred for 24 h to obtain a polyamide acid solution. 10.0 g of dimethylbenzene was added into the polyamide acid solution and the polyamide acid solution was heated to 190°C and stirred for 2 h. Then, the dimethylbenzene was removed from the product system by evaporation at 190°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0097] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 7.439 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 5°C. 7.590 g of s-ODPA was added into the solution and stirred for 24 h to obtain a soluble thermoplastic polyamide acid solution.

[0098] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 160°C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160°C. The solution was cooled to 30°C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 220°C to obtain s-TPI resin.

[0099] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMAc to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 60 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 80°C. A liquid film with a thickness of about 60 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 80°C. Then, the TPI composite film was obtained by drying at 220°C.

[0100] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film where the coating was arranged. The double-sided FCCL sample was obtained by pressing at a high temperature of 350°C for 1 min using a flat plate press.

[0101] Example 6

[0102] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0103] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 1.976 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 5°C. 3.024 g of 6FDA was added into the solution and stirred for 24 h to obtain a polyamide acid solution. 10.0 g of dimethylbenzene was added into the polyamide acid solution and the polyamide acid solution was heated to 190°C and stirred for 2 h. Then, the dimethylbenzene was removed from the product system by evaporation at 190°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0104] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 7.446 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and controlling the temperature of the solution at 5°C. 7.582 g of s-ODPA was added into the solution and stirred for 24 h to obtain a soluble thermoplastic polyamide acid solution.

[0105] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 170°C and stirred for 4 h. Then, the toluene was removed from the solution by evaporation at 170°C. The solution was cooled to 30°C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 220°C to obtain s-TPI resin.

[0106] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMAc to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 60 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 100°C. A liquid film with a thickness of about 60 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 100°C. Then, the TPI composite film was obtained by drying at 220°C.

[0107] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and then the copper foil was pressed for 1 min at a high temperature of 350°C on a flat plate press to obtain a double-sided FCCL sample.

[0108] Example 7

[0109] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0110] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 1.976 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring and controlling the temperature of the solution at 5°C. 3.024 g of 6FDA was added into the solution and stirred for 24 h to obtain a polyamide acid solution. 10.0 g of dimethylbenzene was added into the polyamide acid solution and the polyamide acid solution was heated to 190°C and stirred for 2 h. Then, the dimethylbenzene was removed from the product system by evaporation at 190°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0111] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 7.450 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 15°C. 7.578 g of s-ODPA was added into the solution and stirred for 12 h to obtain a soluble thermoplastic polyamide acid solution.

[0112] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 170°C and stirred for 4 h. Then, the toluene was removed from the solution by evaporation at 170°C. The solution was cooled to 30°C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 220°C to obtain s-TPI resin.

[0113] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMAc to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 60 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 80°C. A liquid film with a thickness of about 60 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 80°C. Then, the TPI composite film was obtained by drying at 220°C.

[0114] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and then the copper foil was pressed for 1 min at a high temperature of 350°C on a flat plate press to obtain a double-sided FCCL sample.

[0115] Example 8

[0116] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0117] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 1.976 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring and the temperature of the solution was controlled at 5°C. 3.024 g of 6FDA was added into the solution and stirred for 24 h to obtain a polyamide acid solution. 10.0 g of dimethylbenzene was added into the polyamide acid solution and the polyamide acid solution was heated to 190°C and stirred for 2 h. Then, the dimethylbenzene was removed from the product system by evaporation at 190°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0118] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 7.452 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 15°C. 7.576 g of s-ODPA was added into the solution and stirred for 12 h to obtain a soluble thermoplastic polyamide acid solution.

[0119] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 160°C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160°C. The solution was cooled to 30°C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 220°C to obtain s-TPI resin.

[0120] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMAc to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 60 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 120°C. A liquid film with a thickness of about 60 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 120°C. Then, the TPI composite film was obtained by drying at 200°C.

[0121] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film where the coating was arranged. The double-sided FCCL sample was obtained by pressing the copper foils on the TPI composite film in a high-temperature flat press at 330°C for 2 min.

[0122] Example 9

[0123] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0124] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 1.976 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring and the temperature of the solution was controlled at 5°C. 3.024 g of 6FDA was added into the solution and stirred for 24 h to obtain a polyamide acid solution. 10.0 g of dimethylbenzene was added into the polyamide acid solution and the polyamide acid solution was heated to 190°C and stirred for 2 h. Then, the dimethylbenzene was removed from the product system by evaporation at 190°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0125] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 7.454 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and controlling the temperature of the solution at 15°C. 7.573 g of s-ODPA was added into the solution and stirred for 12 h to obtain a soluble thermoplastic polyamide acid solution.

[0126] (3) Preparation of s-TPI resin. 21.5 g of toluene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 160°C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160°C. The solution was cooled to 30°C and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then was sufficiently dried at 220°C to obtain s-TPI resin.

[0127] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMAc to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 60 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 150°C. A liquid film with a thickness of about 60 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 150°C. Then, the TPI composite film was obtained by sufficiently drying at 220°C.

[0128] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film where the coating was arranged. The double-sided FCCL sample was obtained by pressing the copper foils on the TPI composite film in a high-temperature flat press at 330°C for 2 min.

[0129] Example 10

[0130] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0131] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 3.953 g of FDA was dispersed in 90.0 g of NMP solvent in a container while stirring and controlling the temperature of the solution at 25°C. 6.047 g of 6FDA was added into the solution and stirred for 16 h to obtain a polyamide acid solution. 15.0 g of toluene was added into the polyamide acid solution and the polyamide acid solution was heated to 160°C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0132] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 9.074 g of TPE-R was added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 25 °C. 8.952 g of s-ODPA and 65.4 g of NMP were added to the solution, and the mixture was stirred for 16 h to obtain a soluble thermoplastic polyamic acid solution.

[0133] (3) Preparation of s-TPI resin. 20.0 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 180 °C and stirred for 4 h. Then, the xylene was evaporated from the product system at 180 °C. The solution was cooled to 30 °C, and water was added to obtain a solid precipitate. The solid precipitate was filtered and thoroughly washed with a mixture of water and methanol at a volume ratio of 2:1, and then thoroughly dried at 200 °C to obtain s-TPI resin.

[0134] (4) Preparation of TPI composite membrane. A PI film is provided, which has a first surface and a second surface arranged relatively parallel to each other. The s-TPI resin obtained in step (3) is dissolved in dichloromethane to obtain a solution with a solid content of 18%. Using a coating machine, a liquid film of about 35 μm thickness is coated on the first surface of the PI film, and most of the solvent is evaporated at 80°C; a liquid film of about 35 μm thickness is coated on the second surface of the PI film, and most of the solvent is evaporated at 80°C. Then, it is thoroughly dried at 200°C to obtain the TPI composite membrane.

[0135] (5) Preparation of double-sided FCCL sample. Using the TPI composite film obtained in step (4), place a copper foil on each side of the TPI composite film with the coating, and press them on a high-temperature flat plate press at 350℃ for 0.5 min to obtain a double-sided FCCL sample.

[0136] Example 11

[0137] This embodiment provides a method for preparing a flexible copper-clad laminate, which includes the following steps:

[0138] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 3.953 g of FDA was dispersed in 90.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25 °C. 6.047 g of 6FDA was added to the solution, and the mixture was stirred for 16 h to obtain a polyamic acid solution. 15.0 g of toluene was added to the polyamic acid solution, and the solution was heated to 160 °C and stirred for 8 h. Then, the toluene was evaporated from the solution at 160 °C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0139] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 18.549 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 25 °C. 19.026 g of s-ODPA, 190.3 g of NMP were added into the solution and stirred for 16 h to obtain a soluble thermoplastic polyamide acid solution.

[0140] (3) Preparation of s-TPI resin. 35.0 g of xylene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 180 °C and stirred for 6 h. Then, the xylene was removed from the product system by evaporation at 180 °C. The solution was cooled to 30 °C and water was added to obtain a solid precipitate. The solid precipitate was filtered and washed with a mixture of water and methanol with a volume ratio of 2:1 and then dried at 200 °C to obtain s-TPI resin.

[0141] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in dichloromethane to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 65 μm on the first surface of the PI film and most of the solvent was removed by evaporation at 80 °C. A liquid film with a thickness of about 65 μm was coated on the second surface of the PI film and most of the solvent was removed by evaporation at 80 °C. Then, the TPI composite film was obtained by drying at 200 °C.

[0142] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used and a copper foil was placed on each side of the TPI composite film provided with a coating layer. The double-sided FCCL sample was obtained by pressing at a high temperature of 350 °C for 0.5 min using a flat plate press.

[0143] Example 12

[0144] The present example provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0145] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 3.953 g of FDA was dispersed in 90.0 g of NMP solvent in a container while stirring and the temperature of the solution was controlled at 25 °C. 6.047 g of 6FDA was added into the solution and stirred for 16 h to obtain a polyamide acid solution. 15.0 g of toluene was added into the polyamide acid solution and the polyamide acid solution was heated to 160 °C and stirred for 8 h. Then, the toluene was removed from the solution by evaporation at 160 °C to obtain an anhydride-terminated X segment polyimide resin solution.

[0146] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 25.837 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 25 °C. 26.776 g of s-ODPA and 354.8 g of NMP were added into the solution and stirred for 16 h to obtain a soluble thermoplastic polyamide acid solution.

[0147] (3) Preparation of s-TPI resin. 70.0 g of xylene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 190 °C and stirred for 4 h. Then, the xylene was evaporated from the product system at 190 °C. The solution was cooled to 30 °C and water was added to obtain a solid precipitate. The solid precipitate was filtered and washed with a mixture of water and methanol in a volume ratio of 2:1 and then dried at 200 °C to obtain s-TPI resin.

[0148] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in dichloromethane to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 65 μm on the first surface of the PI film and most of the solvent was evaporated at 80 °C. A liquid film with a thickness of about 65 μm was coated on the second surface of the PI film and most of the solvent was evaporated at 80 °C. Then, the TPI composite film was obtained by drying at 200 °C.

[0149] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used and a copper foil was placed on each side of the TPI composite film provided with a coating layer. The double-sided FCCL sample was obtained by pressing at a high temperature of 370 °C for 1 min using a flat plate press.

[0150] Example 13

[0151] The present example provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0152] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 3.953 g of FDA was dispersed in 90.0 g of NMP solvent in a container while stirring and the temperature of the solution was controlled at 25 °C. 6.047 g of 6FDA was added into the solution and stirred for 16 h to obtain a polyamide acid solution. 15.0 g of toluene was added into the polyamide acid solution and the polyamide acid solution was heated to 160 °C and stirred for 8 h. Then, the toluene was evaporated from the solution at 160 °C to obtain an anhydride-terminated X segment polyimide resin solution.

[0153] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 33.126 g of TPE-R was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and the temperature of the solution was controlled at 25°C. 34.526 g of s-ODPA and 440.0 g of NMP were added into the solution and stirred for 24 h to obtain a soluble thermoplastic polyamide acid solution.

[0154] (3) Preparation of s-TPI resin. 80.0 g of xylene was added into the soluble thermoplastic polyamide acid solution prepared in step (2) and the polyamide acid solution was heated to 190°C and stirred for 8 h. Then, the xylene was removed from the product system by evaporation at 190°C. The solution was cooled to 30°C and water was added to obtain a solid precipitate. The solid precipitate was filtered and washed with a mixture of water and methanol with a volume ratio of 2:1, and then was dried at 200°C to obtain s-TPI resin.

[0155] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in dichloromethane to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 65 μm on the first surface of the PI film, and most of the solvent was removed by evaporation at 80°C. A liquid film with a thickness of about 65 μm was coated on the second surface of the PI film, and most of the solvent was removed by evaporation at 80°C. Then, the TPI composite film was obtained by drying at 200°C.

[0156] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and then the copper foil was pressed for 1 min at a high temperature of 330°C on a flat plate pressing machine to obtain a double-sided FCCL sample.

[0157] Example 14

[0158] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0159] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 2.725 g of CHPDA was dispersed in 92.0 g of NMP solvent in a container while stirring and the temperature of the solution was controlled at 45°C. 5.275 g of BPAF was added into the solution and stirred for 4 h to obtain a polyamide acid solution. 20.0 g of xylene was added into the polyamide acid solution and the polyamide acid solution was heated to 180°C and stirred for 4 h. Then, the xylene was removed from the product system by evaporation at 180°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0160] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 16.958 g of BAPP was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and controlling the temperature of the solution at 45°C. 5.834 g of s-BPDA, 10.604 g of BPADA, and 96.6 g of NMP were added into the solution, and the solution was stirred for 8 h to obtain a soluble thermoplastic polyamide acid solution.

[0161] (3) Preparation of s-TPI resin. The soluble thermoplastic polyamide acid solution prepared in step (2) was added with 25.0 g of xylene, and the polyamide acid solution was heated to 180°C and stirred for 6 h. Then, the xylene was evaporated from the product system at 180°C. The solution was cooled to 30°C, and a mixture of water and ethanol at a volume ratio of 1:2 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with a mixture of water and ethanol at a volume ratio of 1:2, and then was sufficiently dried at 200°C to obtain s-TPI resin.

[0162] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMF to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 40 μm on the first surface of the PI film, and most of the solvent was volatilized at 120°C. A liquid film with a thickness of about 40 μm was coated on the second surface of the PI film, and most of the solvent was volatilized at 120°C. Then, the TPI composite film was sufficiently dried at 200°C.

[0163] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was placed between two copper foils, and the two sides of the TPI composite film provided with coating were pressed for 2 min at a high temperature flat press at 350°C to obtain a double-sided FCCL sample.

[0164] Example 15

[0165] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0166] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 2.725 g of CHPDA was dispersed in 92.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 45°C. 5.275 g of BPAF was added into the solution, and the solution was stirred for 4 h to obtain a polyamide acid solution. 20.0 g of xylene was added into the polyamide acid solution, and the polyamide acid solution was heated to 180°C and stirred for 4 h. Then, the xylene was evaporated from the product system at 180°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0167] (2) Preparation of soluble thermoplastic polyamide acid solution. Under nitrogen atmosphere, 16.958 g of BAPP was added into the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring and controlling the temperature of the solution at 45°C. 3.768 g of s-BPDA, 14.259 g of BPADA and 243.6 g of NMP were added into the solution, and the reaction was stirred for 8 h to obtain a soluble thermoplastic polyamide acid solution.

[0168] (3) Preparation of s-TPI resin. 50.0 g of dimethylbenzene was added into the soluble thermoplastic polyamide acid solution prepared in step (2), and the polyamide acid solution was heated to 180°C and stirred for 6 h. Then, dimethylbenzene was evaporated from the product system at 180°C. The solution was cooled to 30°C, and a mixture of water and ethanol with a volume ratio of 1:2 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with a mixture of water and ethanol with a volume ratio of 1:2, and then was sufficiently dried at 200°C to obtain s-TPI resin.

[0169] (4) Preparation of TPI composite film. A PI film was provided, which had a first surface and a second surface arranged in relative parallel. The s-TPI resin obtained in step (3) was dissolved in DMF to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 40 μm on the first surface of the PI film, and most of the solvent was volatilized at 150°C; a liquid film with a thickness of about 40 μm was coated on the second surface of the PI film, and most of the solvent was volatilized at 150°C. Then, the TPI composite film was sufficiently dried at 200°C.

[0170] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film where the coating was arranged, and then the copper foil was pressed for 2 min at a high temperature flat press at 330°C to obtain a double-sided FCCL sample.

[0171] Example 16

[0172] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0173] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 2.725 g CHPDA was dispersed in 92.0 g NMP solvent in a container under stirring, and the temperature of the solution was controlled at 45 °C. 5.275 g BPAF was added to the solution, and the reaction was stirred for 4 h to obtain a polyamic acid solution. 20.0 g dimethylbenzene was added to the polyamic acid solution, and the polyamic acid solution was heated to 180 °C, and the reaction was stirred for 4 h. Then, dimethylbenzene was removed from the product system by evaporation at 180 °C to obtain an anhydride-terminated X segment polyimide resin solution.

[0174] (2) Preparation of soluble thermoplastic polyamic acid solution. Under nitrogen atmosphere, 16.958 g BAPP was added to the anhydride-terminated X segment polyimide resin solution prepared in step (1) under stirring, and the temperature of the solution was controlled at 45 °C. 2.795 g s-BPDA, 15.979 g BPADA, and 174.9 g NMP were added to the solution, and the reaction was stirred for 8 h to obtain a soluble thermoplastic polyamic acid solution.

[0175] (3) Preparation of s-TPI resin. 50.0 g dimethylbenzene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 190 °C, and the reaction was stirred for 4 h. Then, dimethylbenzene was removed from the product system by evaporation at 190 °C. The solution was cooled to 30 °C, and a mixture of water and ethanol in a volume ratio of 1:2 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with a mixture of water and ethanol in a volume ratio of 1:2, and then was sufficiently dried at 200 °C to obtain s-TPI resin.

[0176] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMF to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 50 μm on the first surface of the PI film, and most of the solvent was removed by volatilization at 150 °C; a liquid film with a thickness of about 50 μm was coated on the second surface of the PI film, and most of the solvent was removed by volatilization at 150 °C. Then, the TPI composite film was sufficiently dried at 200 °C.

[0177] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and the copper foils were pressed for 2 min on a high-temperature flat plate press at 330 °C to obtain a double-sided FCCL sample.

[0178] Example 17

[0179] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0180] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 2.725 g CHPDA was dispersed in 92.0 g NMP solvent in a container under stirring, and the temperature of the solution was controlled at 45 °C. 5.275 g BPAF was added to the solution, and the reaction was stirred for 4 h to obtain a polyamic acid solution. 20.0 g dimethylbenzene was added to the polyamic acid solution, and the polyamic acid solution was heated to 180 °C, and the reaction was stirred for 4 h. Then, dimethylbenzene was evaporated from the product system at 180 °C to obtain an anhydride-terminated X segment polyimide resin solution.

[0181] (2) Preparation of soluble thermoplastic polyamic acid solution. Under nitrogen atmosphere, 16.958 g BAPP was added to the anhydride-terminated X segment polyimide resin solution prepared in step (1) under stirring, and the temperature of the solution was controlled at 45 °C. 1.884 g s-BPDA, 17.592 g BPADA, and 103.7 g NMP were added to the solution, and the reaction was stirred for 12 h to obtain a soluble thermoplastic polyamic acid solution.

[0182] (3) Preparation of s-TPI resin. 40.0 g dimethylbenzene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 190 °C, and the reaction was stirred for 6 h. Then, dimethylbenzene was evaporated from the product system at 190 °C. The solution was cooled to 30 °C, and a mixture of water and ethanol in a volume ratio of 1:2 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with a mixture of water and ethanol in a volume ratio of 1:2, and then was sufficiently dried at 200 °C to obtain s-TPI resin.

[0183] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in DMF to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 50 μm on the first surface of the PI film, and most of the solvent was volatilized and removed at 150 °C; a liquid film with a thickness of about 50 μm was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 150 °C. Then, the TPI composite film was sufficiently dried at 200 °C.

[0184] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and the copper foils were pressed for 2 min on a high-temperature flat plate press at 350 °C to obtain a double-sided FCCL sample.

[0185] Example 18

[0186] The embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0187] (1) Preparation of the X-segment polyimide resin solution. Under a nitrogen atmosphere, 2.725 g of CHPDA is dispersed in 92.0 g of NMP solvent in a container while stirring, and the temperature of the solution is controlled to be 45 DEG C. 5.275 g of BPAF is added to the solution, and stirring reaction is carried out for 4 h to obtain a polyamic acid solution. 20.0 g of dimethylbenzene is added to the polyamic acid solution, and the polyamic acid solution is heated to 180 DEG C, and stirring reaction is carried out for 4 h. Then, dimethylbenzene is removed from the product system by evaporation at 180 DEG C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0188] (2) Preparation of the soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 16.958 g of BAPP is added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution is controlled to be 45 DEG C. 20.925 g of BPADA and 107.1 g of NMP are added to the solution, and stirring reaction is carried out for 8 h to obtain a soluble thermoplastic polyamic acid solution.

[0189] (3) Preparation of the s-TPI resin. 40.0 g of dimethylbenzene is added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution is heated to 190 DEG C, and stirring reaction is carried out for 6 h. Then, dimethylbenzene is removed from the product system by evaporation at 190 DEG C. The solution is cooled to 30 DEG C, and a mixture of water and ethanol with a volume ratio of 1:2 is added to obtain a solid precipitate; the solid precipitate is filtered and washed with a mixture of water and ethanol with a volume ratio of 1:2, and then is sufficiently dried at 200 DEG C to obtain the s-TPI resin.

[0190] (4) Preparation of the TPI composite film. A PI film is provided, which has a first surface and a second surface arranged in relative parallelism. The s-TPI resin obtained in step (3) is dissolved in DMF to obtain a solution with a solid content of 8%. A coating machine is used to coat a liquid film with a thickness of about 50 μm on the first surface of the PI film, and most of the solvent is volatilized and removed at 150 DEG C; a liquid film with a thickness of about 50 μm is coated on the second surface of the PI film, and most of the solvent is volatilized and removed at 150 DEG C. Then, the TPI composite film is obtained by being sufficiently dried at 200 DEG C.

[0191] (5) Preparation of the double-sided FCCL sample. The TPI composite film obtained in step (4) is used, and a copper foil is arranged on each side of the TPI composite film where the coating is arranged, and then the copper foils are pressed for 2 min on a high-temperature flat plate pressing machine at 350 DEG C to obtain the double-sided FCCL sample.

[0192] Example 19

[0193] The embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0194] (1) Preparation of an X-segment polyimide resin solution. Under a nitrogen atmosphere, 1.551 g of CHPDA is dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution is controlled to be 25 DEG C. 3.449 g of 6FDA is added to the solution, and stirring reaction is performed for 16 h to obtain a polyamic acid solution. 15.0 g of toluene is added to the polyamic acid solution, and the polyamic acid solution is heated to 170 DEG C, and stirring reaction is performed for 4 h. Then, toluene is evaporated and removed from the solution at 170 DEG C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0195] (2) Preparation of a soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 4.997 g of 4,4'-DAT is added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution is controlled to be 25 DEG C. 0.770 g of PMDA, 5.651 g of s-ODPA and 7.0 g of NMP are added to the solution, and stirring reaction is performed for 16 h to obtain a soluble thermoplastic polyamic acid solution.

[0196] (3) Preparation of an s-TPI resin. 21.5 g of toluene is added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution is heated to 170 DEG C, and stirring reaction is performed for 4 h. Then, toluene is evaporated and removed from the solution at 170 DEG C. The solution is cooled to 30 DEG C, and water is added to obtain a solid precipitate; the solid precipitate is filtered and washed with water, and then is sufficiently dried at 200 DEG C to obtain an s-TPI resin.

[0197] (4) Preparation of a TPI composite film. A PI film having a first surface and a second surface arranged in relative parallelism is provided. The s-TPI resin obtained in step (3) is dissolved in r-butyl lactone to obtain a solution with a solid content of 10%. A coating machine is used to coat a liquid film with a thickness of about 45 microns on the first surface of the PI film, and most of the solvent is volatilized and removed at 150 DEG C; a liquid film with a thickness of about 45 microns is coated on the second surface of the PI film, and most of the solvent is volatilized and removed at 150 DEG C. Then, the TPI composite film is sufficiently dried at 250 DEG C.

[0198] (5) Preparation of a double-sided FCCL sample. The TPI composite film obtained in step (4) is used, and a copper foil is placed on each side of the TPI composite film where the coating is arranged, and then the copper foils are pressed for 1 min on a high-temperature flat plate pressing machine at 350 DEG C to obtain a double-sided FCCL sample.

[0199] Example 20

[0200] The embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0201] (1) Preparation of an X-segment polyimide resin solution. Under a nitrogen atmosphere, 1.794 g of CHPHDA is dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution is controlled to be 5 DEG C. 3.206 g of 6FDA is added to the solution, and stirring reaction is performed for 24 h to obtain a polyamic acid solution. 15.0 g of toluene is added to the polyamic acid solution, and the polyamic acid solution is heated to 170 DEG C, and stirring reaction is performed for 8 h. Then, toluene is evaporated from the solution at 170 DEG C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0202] (2) Preparation of a soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 6.699 g of 4,4'-DDS is added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution is controlled to be 5 DEG C. 2.713 g of HQDA, 6.185 g of BTDA and 8.8 g of NMP are added to the solution, and stirring reaction is performed for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0203] (3) Preparation of an s-TPI resin. 21.5 g of toluene is added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution is heated to 170 DEG C, and stirring reaction is performed for 8 h. Then, toluene is evaporated from the solution at 170 DEG C. The solution is cooled to 30 DEG C, and a mixture of water and methanol with a volume ratio of 1:1 is added to obtain a solid precipitate; the solid precipitate is filtered, and washed with water, and then is sufficiently dried at 200 DEG C to obtain an s-TPI resin.

[0204] (4) Preparation of a TPI composite film. A PI film is provided, which has a first surface and a second surface arranged in parallel. The s-TPI resin obtained in step (3) is dissolved in r-butyl lactone to obtain a solution with a solid content of 10%. A coating machine is used to coat a liquid film with a thickness of about 45 microns on the first surface of the PI film, and most of the solvent is volatilized and removed at 150 DEG C; a liquid film with a thickness of about 45 microns is coated on the second surface of the PI film, and most of the solvent is volatilized and removed at 150 DEG C. Then, the TPI composite film is sufficiently dried at 250 DEG C.

[0205] (5) Preparation of a double-sided FCCL sample. The TPI composite film obtained in step (4) is used, and a copper foil is placed on each side of the TPI composite film where the coating is arranged, and then the copper foil is pressed for 1 min on a high-temperature flat plate pressing machine at 370 DEG C to obtain a double-sided FCCL sample.

[0206] Example 21

[0207] The embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0208] (1) Preparation of X segment polyimide resin solution. Under a nitrogen atmosphere, 1.484 g of CHPHDA is dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution is controlled to be 5 DEG C. 3.516 g of BPAFDA is added to the solution, and stirring reaction is performed for 24 h to obtain a polyamic acid solution. 15.0 g of toluene is added to the polyamic acid solution, and the polyamic acid solution is heated to 170 DEG C, and stirring reaction is performed for 8 h. Then, toluene is evaporated from the solution at 170 DEG C to obtain an anhydride-terminated X segment polyimide resin solution.

[0209] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 5.865 g of APB is added to the anhydride-terminated X segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution is controlled to be 5 DEG C. 3.036 g of IBPDA, 5.485 g of BPADA and 8.3 g of NMP are added to the solution, and stirring reaction is performed for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0210] (3) Preparation of s-TPI resin. 21.5 g of toluene is added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution is heated to 170 DEG C, and stirring reaction is performed for 8 h. Then, toluene is evaporated from the solution at 170 DEG C. The solution is cooled to 30 DEG C, and a mixture of water and methanol with a volume ratio of 1:1 is added to obtain a solid precipitate; the solid precipitate is filtered and washed with a mixture of water and methanol with a volume ratio of 1:1, and then is sufficiently dried at 200 DEG C to obtain s-TPI resin.

[0211] (4) Preparation of TPI composite film. A PI film is provided, which has a first surface and a second surface arranged in relative parallel. The s-TPI resin obtained in step (3) is dissolved in r-butyl lactone to obtain a solution with a solid content of 10%. A coating machine is used to coat a liquid film with a thickness of about 45 μm on the first surface of the PI film, and most of the solvent is volatilized and removed at 120 DEG C; a liquid film with a thickness of about 45 μm is coated on the second surface of the PI film, and most of the solvent is volatilized and removed at 120 DEG C. Then, the TPI composite film is sufficiently dried at 220 DEG C.

[0212] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) is used, and a copper foil is placed on each side of the TPI composite film where the coating is arranged, and the copper foil is pressed for 0.5 min on a high-temperature flat plate pressing machine at 350 DEG C to obtain a double-sided FCCL sample.

[0213] Example 22

[0214] The present embodiment provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0215] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 1.775 g of FDA-OH was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 15°C. 3.225 g of BPAFDA was added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution. 15.0 g of toluene was added to the polyamic acid solution, and the polyamic acid solution was heated to 170°C, and the reaction was stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0216] (2) Preparation of a soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 5.778 g of APB was added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 15°C. 2.718 g of TAHQ, 7.023 g of BPADA, and 8.8 g of NMP were added to the solution, and the reaction was stirred for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0217] (3) Preparation of s-TPI resin. 21.5 g of toluene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 170°C, and the reaction was stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:1 was added to obtain a solid precipitate; the solid precipitate was filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:1, and then dried thoroughly at 220°C to obtain s-TPI resin.

[0218] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in r-butyl lactone to obtain a solution with a solid content of 10%. A coating machine was used to coat a liquid film with a thickness of about 45 μm on the first surface of the PI film, and most of the solvent was volatilized and removed at 120°C; a liquid film with a thickness of about 45 μm was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 120°C. Then, it was dried thoroughly at 200°C to obtain a TPI composite film.

[0219] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film where the coating was provided, and the high-temperature flat plate press was pressed at 370°C for 0.5 min to obtain a double-sided FCCL sample.

[0220] Example 23

[0221] The present embodiment provides a preparation method of flexible copper-clad plate, which comprises the following steps:

[0222] (1) Preparation of X segment polyimide resin solution. Under nitrogen atmosphere, 1.713 g CHPHDA was dispersed in 95.0 g NMP solvent in a container under stirring, and the temperature of the solution was controlled at 15°C. 3.287 g 6FCDA was added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution. 15.0 g toluene was added to the polyamic acid solution, and the polyamic acid solution was heated to 170°C, and the reaction was stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C to obtain an anhydride-terminated X segment polyimide resin solution.

[0223] (2) Preparation of soluble thermoplastic polyamic acid solution. Under nitrogen atmosphere, 5.596 g 1,4-CHDA was added to the anhydride-terminated X segment polyimide resin solution prepared in step (1) under stirring, and the temperature of the solution was controlled at 15°C. 1.511 g MDPA, 22.353 g BPADA and 137.8 g NMP were added to the solution, and the reaction was stirred for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0224] (3) Preparation of s-TPI resin. 40.0 g toluene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 170°C, and the reaction was stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C. The solution was cooled to 30°C, and a mixture of water and methanol with a volume ratio of 1:1 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with a mixture of water and methanol with a volume ratio of 1:1, and then dried at 200°C to obtain s-TPI resin.

[0225] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in r-butyl lactone to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 80 μm on the first surface of the PI film, and most of the solvent was volatilized and removed at 150°C; a liquid film with a thickness of about 80 μm was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 150°C. Then, it was dried at 200°C to obtain a TPI composite film.

[0226] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film where the coating was arranged, and the high-temperature flat plate press was pressed at 370°C for 0.5 min to obtain a double-sided FCCL sample.

[0227] Example 24

[0228] The present embodiment provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0229] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 2.091 g of FDA-F was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 2.909 g of 6FCDA was added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution. 15.0 g of toluene was added to the polyamic acid solution, and the polyamic acid solution was heated to 170°C and stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0230] (2) Preparation of a soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 1.901 g of 1,6-HDA was added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 25°C. 1.508 g of CBDA, 4.098 g of BPADA, and 5.4 g of NMP were added to the solution, and the reaction was stirred for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0231] (3) Preparation of s-TPI resin. 21.5 g of toluene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 170°C and stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:1 was added to obtain a solid precipitate. The solid precipitate was filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:1, and then dried thoroughly at 200°C to obtain s-TPI resin.

[0232] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in r-butyl lactone to obtain a solution with a solid content of 12%. A coating machine was used to coat a liquid film with a thickness of about 35 μm on the first surface of the PI film, and most of the solvent was volatilized and removed at 100°C. A liquid film with a thickness of about 35 μm was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 100°C. Then, the TPI composite film was dried thoroughly at 220°C.

[0233] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film where the coating was provided. The copper foils were pressed together on a high-temperature flat plate press at 330°C for 0.5 min to obtain a double-sided FCCL sample.

[0234] Example 25

[0235] The present embodiment provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0236] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 2.123 g of FDA-OH was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 2.877 g of BPAF was added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution. 15.0 g of toluene was added to the polyamic acid solution, and the polyamic acid solution was heated to 170°C and stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0237] (2) Preparation of a soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 11.333 g of BAPS-M was added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 25°C. 1.469 g of HPMDA, 9.949 g of BPADA, and 27.8 g of NMP were added to the solution, and the reaction was stirred for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0238] (3) Preparation of s-TPI resin. 21.5 g of toluene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 170°C and stirred for 8 h. Then, the toluene was evaporated from the solution at 170°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:1 was added to obtain a solid precipitate; the solid precipitate was filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:1, and then dried thoroughly at 200°C to obtain s-TPI resin.

[0239] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in r-butyl lactone to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 50 μm on the first surface of the PI film, and most of the solvent was volatilized and removed at 120°C; a liquid film with a thickness of about 50 μm was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 120°C. Then, it was dried thoroughly at 200°C to obtain a TPI composite film.

[0240] (5) Preparation of double-sided FCCL sample. Using the TPI composite film obtained in step (4), place a piece of copper foil on each side of the TPI composite film provided with coating, and press for 0.5 min on a high-temperature flat press at 350°C to obtain a double-sided FCCL sample.

[0241] Example 26

[0242] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0243] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 2.482 g of CHPDA was dispersed in 92.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 45°C. 5.518 g of 6FDA was added to the solution, and the reaction was stirred for 8 h to obtain a polyamic acid solution. 15.0 g of xylene was added to the polyamic acid solution, and the polyamic acid solution was heated to 190°C and stirred for 2 h. Then, the xylene was evaporated from the product system at 190°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0244] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 0.991 g of p-PDA and 24.106 g of APB were added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 45°C. 28.848 g of BTDA and 247.8 g of NMP were added to the solution, and the reaction was stirred for 8 h to obtain a soluble thermoplastic polyamic acid solution.

[0245] (3) Preparation of s-TPI resin. 50.0 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 190°C and stirred for 2 h. Then, the xylene was evaporated from the product system at 190°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:3, and then dried thoroughly at 150°C to obtain s-TPI resin.

[0246] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution with a solid content of 8%. An 80-μm-thick liquid film was coated on the first surface of the PI film using a coating machine, and most of the solvent was volatilized and removed at 120°C; an 80-μm-thick liquid film was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 120°C. Then, the PI film was dried thoroughly at 200°C to obtain a TPI composite film.

[0247] (5) Preparation of double-sided FCCL sample. Using the TPI composite film obtained in step (4), a piece of copper foil was placed on each side of the TPI composite film where the coating was provided, and the copper foils were pressed together on a high-temperature flat press at 330°C for 0.5 min to obtain a double-sided FCCL sample.

[0248] Example 27

[0249] The present embodiment provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0250] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 2.610 g of CHPDA was dispersed in 92.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 45°C. 5.390 g of BPAF was added to the solution, and the reaction was stirred for 8 h to obtain a polyamic acid solution. 15.0 g of xylene was added to the polyamic acid solution, and the polyamic acid solution was heated to 190°C and stirred for 4 h. Then, the xylene was evaporated from the product system at 190°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0251] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 6.560 g of 4,4'-ODA and 13.449 g of BAPP were added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 45°C. 33.214 g of BPADA and 244.9 g of NMP were added to the solution, and the reaction was stirred for 8 h to obtain a soluble thermoplastic polyamic acid solution.

[0252] (3) Preparation of s-TPI resin. 40.0 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 190°C and stirred for 4 h. Then, the xylene was evaporated from the product system at 190°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with water, and then dried at 150°C to obtain s-TPI resin.

[0253] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution with a solid content of 8%. A coating machine was used to coat a liquid film with a thickness of about 65 μm on the first surface of the PI film, and most of the solvent was volatilized and removed at 120°C; a liquid film with a thickness of about 65 μm was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 120°C. Then, the TPI composite film was sufficiently dried at 180°C.

[0254] (5) Preparation of double-sided FCCL sample. Using the TPI composite film obtained in step (4), a piece of copper foil was placed on each side of the TPI composite film where the coating was provided, and the copper foils were pressed together on a high-temperature flat press at 330°C for 0.5 min to obtain a double-sided FCCL sample.

[0255] Example 28

[0256] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0257] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 2.610 g of FDA-OH was dispersed in 92.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 45°C. 5.390 g of BPAFDA was added to the solution, and the reaction was stirred for 8 h to obtain a polyamic acid solution. 15.0 g of xylene was added to the polyamic acid solution, and the polyamic acid solution was heated to 190°C and stirred for 4 h. Then, the xylene was evaporated from the product system at 190°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0258] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 1.527 g of m-TD and 4.908 g of TPE-R were added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 45°C. 7.195 g of BTDA and 21.6 g of NMP were added to the solution, and the reaction was stirred for 8 h to obtain a soluble thermoplastic polyamic acid solution.

[0259] (3) Preparation of s-TPI resin. 21.5 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 190°C and stirred for 3 h. Then, the xylene was evaporated from the product system at 190°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with water, and then dried at 150°C to obtain s-TPI resin.

[0260] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution with a solid content of 12%. A liquid film with a thickness of about 45 μm was coated on the first surface of the PI film using a coating machine, and most of the solvent was volatilized and removed at 120°C; a liquid film with a thickness of about 45 μm was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 120°C. Then, the TPI composite film was sufficiently dried at 200°C.

[0261] (5) Preparation of double-sided FCCL sample. Using the TPI composite film obtained in step (4), a piece of copper foil was placed on each side of the TPI composite film provided with a coating, and the copper foils were pressed together on a high-temperature flat plate press at 330°C for 0.5 min to obtain a double-sided FCCL sample.

[0262] Example 29

[0263] The present embodiment provides a preparation method of a flexible copper-clad plate, which comprises the following steps:

[0264] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 2.661 g of CHPDA was dispersed in 92.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 15°C. 5.339 g of 6FCDA was added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution. 15.0 g of xylene was added to the polyamic acid solution, and the polyamic acid solution was heated to 180°C and stirred for 4 h. Then, the xylene was evaporated from the product system at 180°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0265] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 7.279 g of TFMB, 29.493 g of BAPS-M, and 28.811 g of BTDA were added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 15°C. 294.3 g of NMP was added to the solution, and the reaction was stirred for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0266] (3) Preparation of s-TPI resin. 50.0 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 180°C and stirred for 6 h. Then, the xylene was evaporated from the product system at 180°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with water, and then dried at 150°C to obtain s-TPI resin.

[0267] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface disposed in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution having a solid content of 8%. A coating machine was used to coat the first surface of the PI film with a liquid film having a thickness of about 80 μm, and most of the solvent was removed by volatilization at 150°C. The second surface of the PI film was coated with a liquid film having a thickness of about 80 μm, and most of the solvent was removed by volatilization at 150°C. Subsequently, the TPI composite film was sufficiently dried at 250°C to obtain a TPI composite film.

[0268] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film on which a coating was disposed. The copper foils were pressed together in a high-temperature flat press at 370°C for 0.5 min to obtain a double-sided FCCL sample.

[0269] Example 30

[0270] The present example provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0271] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 1.758 g of CHPHDA was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 15°C. 3.242 g of BPAF was added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution. 15.0 g of xylene was added to the polyamic acid solution, and the polyamic acid solution was heated to 180°C and stirred for 2 h. Subsequently, the xylene was removed from the product system by evaporation at 180°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0272] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 2.676 g of 4,4'-DABA, 13.770 g of APB, and 17.930 g of s-ODPA were added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 15°C. 157.5 g of NMP was added to the solution, and the reaction was stirred for 24 h to obtain a soluble thermoplastic polyamic acid solution.

[0273] (3) Preparation of s-TPI resin. 40.0 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 180°C and stirred for 2 h. Subsequently, the xylene was removed from the product system by evaporation at 190°C. The solution was cooled to 30°C, and a mixture of water and methanol in a volume ratio of 1:3 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 150°C to obtain s-TPI resin.

[0274] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface disposed in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution having a solid content of 8%. A coating machine was used to coat a liquid film having a thickness of about 80 μm on the first surface of the PI film, and most of the solvent was removed by volatilization at 120°C; a liquid film having a thickness of about 80 μm was coated on the second surface of the PI film, and most of the solvent was removed by volatilization at 120°C. Thereafter, the TPI composite film was sufficiently dried at 200°C to obtain a TPI composite film.

[0275] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each of the two sides of the TPI composite film on which a coating was disposed, and the copper foils were pressed together on a high-temperature flat-plate press at 350°C for 0.5 min to obtain a double-sided FCCL sample.

[0276] Example 31

[0277] The present example provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0278] (1) Preparation of X-segmented polyimide resin solution. Under a nitrogen atmosphere, 1.852 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 3.148 g of 6FDA was added to the solution, and the reaction was stirred for 12 h to obtain a polyamic acid solution. 15.0 g of xylene was added to the polyamic acid solution, and the polyamic acid solution was heated to 180°C, and the reaction was stirred for 2 h. Thereafter, the xylene was removed from the product system by evaporation at 180°C to obtain an anhydride-terminated X-segmented polyimide resin solution.

[0279] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 1.368 g of m-PDA, 12.765 g of BAPS-M, and 13.054 g of BTDA were added to the anhydride-terminated X-segmented polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 25°C. 128.7 g of NMP was added to the solution, and the reaction was stirred for 12 h to obtain a soluble thermoplastic polyamic acid solution.

[0280] (3) Preparation of s-TPI resin. 40.0 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 180°C, and the reaction was stirred for 2 h. Thereafter, the xylene was removed from the product system by evaporation at 180°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with water, and then dried at 150°C to obtain s-TPI resin.

[0281] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution having a solid content of 8%. A coating machine was used to coat the first surface of the PI film with a liquid film having a thickness of about 80 μm, and most of the solvent was removed by volatilization at 120°C. The second surface of the PI film was coated with a liquid film having a thickness of about 80 μm, and most of the solvent was removed by volatilization at 120°C. Subsequently, the TPI composite film was sufficiently dried at 200°C to obtain a TPI composite film.

[0282] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer. The copper foils were pressed together on a high-temperature flat press at 350°C for 0.5 min to obtain a double-sided FCCL sample.

[0283] Example 32

[0284] The present example provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0285] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 1.939 g of FDA was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 3.061 g of BPAF was added to the solution, and the reaction was stirred for 16 h to obtain a polyamic acid solution. 15.0 g of xylene was added to the polyamic acid solution, and the polyamic acid solution was heated to 180°C, and the reaction was stirred for 4 h. Subsequently, the xylene was removed from the product system by evaporation at 180°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0286] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 1.888 g of 3,4'-ODA and 2.001 g of 4,4'-DAT were added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 25°C. 5.757 g of BTDA and 14.6 g of NMP were added to the solution, and the reaction was stirred for 16 h to obtain a soluble thermoplastic polyamic acid solution.

[0287] (3) Preparation of s-TPI resin. 21.5 g of xylene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 180°C, and the reaction was stirred for 4 h. Subsequently, the xylene was removed from the product system by evaporation at 180°C. The solution was cooled to 30°C, and water was added to obtain a solid precipitate. The solid precipitate was filtered and washed with water, and then dried at 150°C to obtain s-TPI resin.

[0288] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface disposed in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution having a solid content of 12%. A coating machine was used to coat the first surface of the PI film with a liquid film having a thickness of about 45 μm, and most of the solvent was removed by volatilization at 120°C. The second surface of the PI film was coated with a liquid film having a thickness of about 45 μm, and most of the solvent was removed by volatilization at 120°C. Thereafter, the TPI composite film was sufficiently baked at 200°C to obtain a TPI composite film.

[0289] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each of the two sides of the TPI composite film on which a coating was provided. The copper foils were pressed together in a high-temperature flat press at 350°C for 1 min to obtain a double-sided FCCL sample.

[0290] Example 33

[0291] The present example provides a method for preparing a flexible copper-clad plate, which comprises the following steps:

[0292] (1) Preparation of X-segment polyimide resin solution. Under a nitrogen atmosphere, 1.968 g of FDA-F was dispersed in 95.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 3.032 g of 6FDA was added to the solution, and the reaction was stirred for 16 h to obtain a polyamic acid solution. 15.0 g of dimethylbenzene was added to the polyamic acid solution, and the polyamic acid solution was heated to 190°C, and the reaction was stirred for 2 h. Thereafter, dimethylbenzene was removed from the product system by evaporation at 190°C to obtain an anhydride-terminated X-segment polyimide resin solution.

[0293] (2) Preparation of soluble thermoplastic polyamic acid solution. Under a nitrogen atmosphere, 1.636 g of 4,4'-MDA and 3.619 g of APB were added to the anhydride-terminated X-segment polyimide resin solution prepared in step (1) while stirring, and the temperature of the solution was controlled at 25°C. 6.181 g of BTDA and 16.4 g of NMP were added to the solution, and the reaction was stirred for 16 h to obtain a soluble thermoplastic polyamic acid solution.

[0294] (3) Preparation of s-TPI resin. 21.5 g of dimethylbenzene was added to the soluble thermoplastic polyamic acid solution prepared in step (2), and the polyamic acid solution was heated to 190°C, and the reaction was stirred for 2 h. Thereafter, dimethylbenzene was removed from the product system by evaporation at 190°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate. The solid precipitate was filtered and washed with a mixture of water and methanol at a volume ratio of 1:3, and then was sufficiently baked at 150°C to obtain s-TPI resin.

[0295] (4) Preparation of TPI composite film. A PI film having a first surface and a second surface disposed in relative parallel was provided. The s-TPI resin obtained in step (3) was dissolved in NMP to obtain a solution having a solid content of 10%. A coating machine was used to coat a liquid film having a thickness of about 50 μm on the first surface of the PI film, and most of the solvent was removed by volatilization at 120°C; a liquid film having a thickness of about 50 μm was coated on the second surface of the PI film, and most of the solvent was removed by volatilization at 120°C. Thereafter, the TPI composite film was sufficiently dried at 200°C to obtain a TPI composite film.

[0296] (5) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (4) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and the copper foil was pressed in a high-temperature flat press at 350°C for 1 min to obtain a double-sided FCCL sample.

[0297] Comparative Example 1

[0298] Comparative Example 1 used the same kind and amount of raw materials as in Example 10, but did not have a block structure.

[0299] In this comparative example, the flexible copper-clad plate was prepared as follows:

[0300] (1) Preparation of non-blocked polyamide acid solution. Under a nitrogen atmosphere, 3.953 g of FDA, 9.074 g of TPE-R were dispersed in 155.4 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 6.047 g of 6FDA and 8.952 g of s-ODPA were added to the solution, and the reaction was stirred for 16 h to obtain a polyamide acid solution.

[0301] (2) Preparation of non-blocked TPI resin. 35.0 g of dimethylbenzene was added to the solution prepared in step (1), and the polyamide acid solution was heated to 180°C, and the reaction was stirred for 6 h. Thereafter, dimethylbenzene was removed from the product system by evaporation at 180°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with a mixture of water and methanol at a volume ratio of 1:3, and then dried at 200°C to obtain a non-blocked TPI resin.

[0302] (3) Preparation of TPI composite film. A PI film having a first surface and a second surface disposed in parallel to each other was provided. The non-blocked polyamic acid solution obtained in step (1) was used to coat a liquid film of about 35 μm in thickness on the first surface of the PI film using a coating machine, and most of the solvent was removed by volatilization at 120°C. A liquid film of about 35 μm in thickness was coated on the second surface of the PI film, and most of the solvent was removed by volatilization at 120°C. Thereafter, high-temperature imidization was performed at 350°C for 10 min to obtain a TPI composite film.

[0303] (4) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (3) was used, and a copper foil was placed on each of the two sides of the TPI composite film on which a coating was provided, and the copper foils were pressed together on a high-temperature flat-plate press at 380°C for 1 min to obtain a double-sided FCCL sample.

[0304] Comparative Example 2

[0305] In Comparative Example 2, the same kinds and amounts of raw materials as in Example 13 were used, but without a block structure.

[0306] In the present comparative example, the flexible copper-clad plate was prepared as follows:

[0307] (1) Preparation of non-blocked polyamic acid solution. Under a nitrogen atmosphere, 3.953 g of FDA, 33.126 g of TPE-R were dispersed in 530.0 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 6.047 g of 6FDA and 34.526 g of s-ODPA were added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution.

[0308] (2) Preparation of non-blocked TPI resin. 95.0 g of xylene was added to the solution prepared in step (1), and the polyamic acid solution was heated to 180°C, and the reaction was stirred for 6 h. Thereafter, the xylene was removed from the product system by evaporation at 180°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate. The solid precipitate was filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:3, and was then dried thoroughly at 200°C to obtain a non-blocked TPI resin.

[0309] (3) Preparation of TPI composite film. A PI film having a first surface and a second surface disposed in parallel to each other was provided. The non-blocked polyamic acid solution obtained in step (1) was used to coat a liquid film of about 40 μm in thickness on the first surface of the PI film using a coating machine, and most of the solvent was removed by volatilization at 120°C. A liquid film of about 40 μm in thickness was coated on the second surface of the PI film, and most of the solvent was removed by volatilization at 120°C. Thereafter, high-temperature imidization was performed at 350°C for 10 min to obtain a TPI composite film.

[0310] (4) Double-sided FCCL sample preparation. Using the TPI composite film obtained in step (3), a piece of copper foil was placed on each side of the TPI composite film provided with a coating, and the two were pressed together on a high-temperature flat press at 380°C for 1 min to obtain a double-sided FCCL sample.

[0311] Comparative Example 3

[0312] Comparative Example 3 used the same types and amounts of raw materials as Example 14, but without a block structure.

[0313] In this comparative example, the flexible copper-clad plate was prepared as follows:

[0314] (1) Preparation of non-blocked polyamic acid solution. Under a nitrogen atmosphere, 2.725 g of CHPDA, 16.958 g of BAPP were dispersed in 188.6 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 5.275 g of BPAF, 5.834 g of s-BPDA, and 10.604 g of BPADA were added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution.

[0315] (2) Preparation of non-blocked TPI resin. 45.0 g of xylene was added to the solution prepared in step (1), and the polyamic acid solution was heated to 180°C and stirred for 8 h. Then, the xylene was evaporated from the product system at 180°C. The solution was cooled to 30°C, and a mixture of water and methanol in a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed thoroughly with a mixture of water and methanol in a volume ratio of 1:3, and then dried thoroughly at 200°C to obtain a non-blocked TPI resin.

[0316] (3) Preparation of TPI composite film. A PI film was provided, which had a first surface and a second surface arranged in relative parallel. Due to the poor solubility of the non-blocked TPI resin obtained in step (2), the process of dissolving and then coating was difficult. Using the non-blocked polyamic acid solution obtained in step (1), a liquid film about 30 μm thick was coated on the first surface of the PI film using a coater, and most of the solvent was volatilized and removed at 100°C; a liquid film about 30 μm thick was coated on the second surface of the PI film, and most of the solvent was volatilized and removed at 100°C. Then, the imidization process was completed by high-temperature treatment at 350°C for 10 min to obtain a TPI composite film.

[0317] (4) Double-sided FCCL sample preparation. Using the TPI composite film obtained in step (3), a piece of copper foil was placed on each side of the TPI composite film provided with a coating, and the two were pressed together on a high-temperature flat press at 380°C for 2 min to obtain a double-sided FCCL sample.

[0318] Comparative Example 4

[0319] Comparative Example 4 uses the same kind and amount of raw materials as Example 18, but does not have a block structure.

[0320] In this comparative example, the flexible copper-clad plate is prepared as follows:

[0321] (1) Preparation of non-blocked polyamic acid solution. Under a nitrogen atmosphere, 2.725 g of CHPDA, 16.958 g of BAPP, 5.275 g of BPAF, and 20.925 g of BPADA are dispersed in 199.1 g of NMP solvent in a container while stirring, and the temperature of the solution is controlled at 25°C. The solution is stirred for 24 h to obtain a polyamic acid solution.

[0322] (2) Preparation of non-blocked TPI resin. 60.0 g of xylene is added to the solution prepared in step (1), and the polyamic acid solution is heated to 190°C and stirred for 4 h. Then, the xylene is evaporated from the product system at 190°C. The solution is cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 is added to obtain a solid precipitate. The solid precipitate is filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:3, and then dried thoroughly at 200°C to obtain a non-blocked TPI resin.

[0323] (3) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel is provided. The non-blocked polyamic acid solution obtained in step (1) is used to coat a liquid film of about 30 μm thick on the first surface of the PI film using a coating machine, and most of the solvent is volatilized and removed at 120°C. A liquid film of about 30 μm thick is coated on the second surface of the PI film, and most of the solvent is volatilized and removed at 120°C. Then, high-temperature imidization is performed at 350°C for 10 min to obtain a TPI composite film.

[0324] (4) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (3) is used, and a copper foil is placed on each side of the TPI composite film where the coating is provided, and then pressed in a high-temperature flat press at 380°C for 1 min to obtain a double-sided FCCL sample.

[0325] Comparative Example 5

[0326] Comparative Example 5 uses the same kind and amount of raw materials as Example 28, but does not have a block structure.

[0327] In this comparative example, the flexible copper-clad plate is prepared as follows:

[0328] (1) Preparation of non-blocked polyamic acid solution. Under nitrogen atmosphere, 2.610 g of FDA-OH, 1.527 g of m-TD, and 4.908 g of TPE-R were dispersed in 113.6 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 5.390 g of BPAFDA and 7.195 g of BTDA were added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution.

[0329] (2) Preparation of non-blocked TPI resin. 36.5 g of xylene was added to the solution prepared in step (1), and the polyamic acid solution was heated to 180°C, and the reaction was stirred for 8 h. Then, the xylene was evaporated from the product system at 180°C. The solution was cooled to 30°C, and a mixture of water and methanol at a volume ratio of 1:3 was added to obtain a solid precipitate; the solid precipitate was filtered and washed with a mixture of water and methanol at a volume ratio of 1:3, and then dried at 200°C to obtain a non-blocked TPI resin.

[0330] (3) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The non-blocked polyamic acid solution obtained in step (1) was used to coat a liquid film of about 35 μm thick on the first surface of the PI film using a coating machine, and most of the solvent was volatilized at 120°C; a liquid film of about 35 μm thick was coated on the second surface of the PI film, and most of the solvent was volatilized at 120°C. Then, high-temperature imidization was carried out at 350°C for 10 min to obtain a TPI composite film.

[0331] (4) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (3) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and then pressed in a high-temperature flat press at 380°C for 1 min to obtain a double-sided FCCL sample.

[0332] Comparative Example 6

[0333] In the present comparative example, the preparation method of the flexible copper-clad plate was as follows:

[0334] (1) Preparation of non-blocked polyamic acid solution. Under nitrogen atmosphere, 2.610 g of FDA-OH, 1.527 g of m-TD, and 4.908 g of TPE-R were dispersed in 113.6 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 5.390 g of BPAFDA and 7.195 g of BTDA were added to the solution, and the reaction was stirred for 24 h to obtain a polyamic acid solution.

[0335] (2) Preparation of non-blocked TPI resin. 35.0 g of xylene was added to the solution prepared in step (1), and the polyamide acid solution was heated to 180°C and stirred for 4 h. Then, the xylene was evaporated from the product system at 180°C. The solution was cooled to 30°C, and a solid precipitate was obtained by adding a mixture of water and methanol at a volume ratio of 1:3. The solid precipitate was filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:3, and then dried thoroughly at 200°C to obtain a non-blocked TPI resin.

[0336] (3) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The non-blocked polyamide acid solution obtained in step (1) was used to coat a liquid film of about 30 μm in thickness on the first surface of the PI film using a coating machine, and most of the solvent was volatilized at 120°C. A liquid film of about 30 μm in thickness was coated on the second surface of the PI film, and most of the solvent was volatilized at 120°C. Then, high-temperature imidization was performed at 350°C for 10 min to obtain a TPI composite film.

[0337] (4) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (3) was used, and a copper foil was placed on each side of the TPI composite film where the coating was arranged, and then the copper foils were pressed together on a high-temperature flat press at 380°C for 1 min to obtain a double-sided FCCL sample.

[0338] Comparative Example 7

[0339] In the present comparative example, the flexible copper-clad plate was prepared as follows:

[0340] (1) Preparation of non-blocked polyamide acid solution. Under a nitrogen atmosphere, 16.703 g of BAPP was dispersed in 170.2 g of NMP solvent in a container while stirring, and the temperature of the solution was controlled at 25°C. 5.746 g of s-BPDA and 11.083 g of BPADA were added to the solution, and stirring was performed for 12 h to obtain a polyamide acid solution.

[0341] (2) Preparation of non-blocked TPI resin. 45.0 g of xylene was added to the solution prepared in step (1), and the polyamide acid solution was heated to 180°C and stirred for 4 h. Then, the xylene was evaporated from the product system at 180°C. The solution was cooled to 30°C, and a solid precipitate was obtained by adding a mixture of water and methanol at a volume ratio of 1:3. The solid precipitate was filtered and washed thoroughly with a mixture of water and methanol at a volume ratio of 1:3, and then dried thoroughly at 200°C to obtain a non-blocked TPI resin.

[0342] (3) Preparation of TPI composite film. A PI film having a first surface and a second surface arranged in relative parallel was provided. The non-blocked polyamide acid solution obtained in step (1) was used to coat a liquid film of about 50 μm in thickness on the first surface of the PI film using a coating machine, and most of the solvent was removed by volatilization at 150°C; a liquid film of about 50 μm in thickness was coated on the second surface of the PI film, and most of the solvent was removed by volatilization at 150°C. Then, high-temperature imidization was carried out at 350°C for 10 min to obtain a TPI composite film.

[0343] (4) Preparation of double-sided FCCL sample. The TPI composite film obtained in step (3) was used, and a copper foil was placed on each side of the TPI composite film provided with a coating layer, and then the copper foils were pressed together on a high-temperature flat plate press at 380°C for 1 min to obtain a double-sided FCCL sample.

[0344] Performance characterization:

[0345] (I) The structural parameters of the soluble thermoplastic polyimide resins obtained in the above examples and comparative examples are shown in Table 2.

[0346] Table 2

[0347]

[0348] Table 2

[0349]

[0350] Figure 1 The structural schematic diagram of the s-TPI resin obtained in Example 1-3 of the present application is shown, Figure 2 The structural schematic diagram of the s-TPI resin obtained in Example 4-6 of the present application is shown, Figure 3 The structural schematic diagram of the TPI resin obtained in Example s-7-9 of the present application is shown, Figure 4 The structural schematic diagram of the s-TPI resin obtained in Example 10-12 of the present application is shown, Figure 5 The structural schematic diagram of the s-TPI resin obtained in Example 13-15 of the present application is shown, Figure 6 The structural schematic diagram of the s-TPI resin obtained in Example 16-18 of the present application is shown, Figure 7 The structural schematic diagram of the s-TPI resin obtained in Example 19-22 of the present application is shown, Figure 8 The structural schematic diagram of the s-TPI resin obtained in Example 23-26 of the present application is shown, Figure 9 The structural schematic diagram of the TPI resin obtained in Example s-27-30 of the present application is shown, Figure 10 The structural schematic diagram of the s-TPI resin obtained in Example 31-33 of the present application is shown, Figure 11Structural diagrams of s-TPI resins obtained in Comparative Examples 1-4 are shown, Figure 12 Structural diagrams of s-TPI resins obtained in Comparative Examples 5-7 are shown.

[0351] (II) The properties of the soluble thermoplastic polyimide resin films obtained in the above examples and comparative examples are shown in Table 3.

[0352] (1) Thickness test of TPI layer in TPI composite film: The thickness of the TPI layer was tested using a micrometer.

[0353] (2) Solubility test of s-TPI resin: 100 g of NMP solvent was taken and the synthesized s-TPI resin solid was added in batches until the added resin raw material could not be completely dissolved at room temperature. During this period, the temperature can be briefly raised to 80°C to promote dissolution. According to the maximum solid amount that can be dissolved at room temperature, the solubility of the s-TPI resin is determined.

[0354] (3) Glass transition temperature (Tg) test: TA's Q800 was used to test the glass transition temperature of the TPI composite film. The TPI composite film sample was fixed on the tester using a film stretching clamp, the starting temperature was set to 30°C, and the temperature was raised to 400°C at a rate of 10°C / min and then naturally cooled without stopping, the tester continuously collected sample data during the heating process, and finally the glass transition temperature of the TPI composite film was determined according to the peak value of tanσ.

[0355] (4) Heat resistance test of s-TPI resin: TA's Q50 was used to test the thermal decomposition temperature of the s-TPI resin. The temperature conditions for the test were: starting at 30°C, raising the temperature to 800°C at a rate of 10°C / min, and naturally cooling. The temperature at which 5% weight loss occurs is the thermal decomposition temperature of the s-TPI resin.

[0356] (5) Bonding strength test: a universal testing tensile machine was used to test the peel strength of a flexible copper clad laminate (FCCL) sample; when the separation interface is TPI and the copper foil layer, the bonding strength of TPI and the copper foil layer is obtained; when the separation interface is TPI and the PI layer, the bonding strength of TPI and the PI layer is obtained. The copper foil layer on the FCCL sample was etched into a rectangular pattern with a width of 3 mm and a length of more than 20 cm. The copper strip was peeled off from the polyimide insulating layer by about 5 cm, and after peeling, a flat clamp was used to fix the flexible copper clad laminate sample on the clamp, and the peeled copper strip was fixed to the movable clamp. The force value range of the tensile machine clamp was 20 N. The universal testing tensile machine was started to stretch at a rate of 50.8 mm / min, and the copper strip of the glass was kept at a 90° angle with the plane of the flexible copper clad laminate sample during stretching. The peeling force value during stretching was recorded in real time, and finally the flat and stable section on the curve was selected, and the peel strength of the FCCL sample was calculated according to the formula "peel strength = peeling force value / copper strip width". The etching method of the FCCL includes the following steps: first, prepare an acidic CuCl2 etching solution with pH = 1, then immerse the flexible copper clad laminate sample in the etching solution prepared above, and stop soaking when the copper foil surface is etched away.

[0357] Table 3 upper

[0358]

[0359] Table 3 lower

[0360]

[0361] From the above performance characterization, it can be found that:

[0362] Comparing Examples 10, 13, 14, 18, 28 with Comparative Examples 1-5. Comparative Examples 1-5 use the same monomer species and proportion as Examples 10, 13, 14, 18, 28, but without forming blocks, resulting in a non-block random copolymer structure. Without the block structure and X segment block, the solubility of the polyimide resin in Comparative Examples 1-5 is only below 3 g / 100 g solvent, poor solubility; while in the examples of the present application, the bulky functional group forms the X segment, which can maximize the intermolecular spacing and increase the solubility. In Comparative Examples 1-5, the flexible group and the bulky functional group in the polyimide resin main chain are mixed with each other, the flexibility of the whole molecular main chain is reduced, resulting in a glass transition temperature 40-70°C higher than that of the s-TPI resin in the examples; while in the examples, the L segment block formed by the flexible group does not have a bulky functional group, and has high flexibility, so that the molecular main chain has high flexibility, and the s-TPI resin has low glass transition temperature. Because the polyimide resin in the comparative examples has high glass transition temperature, it is difficult to bond the polyimide resin and the copper foil or PI film by high temperature pressing. These comparison results fully embody the superiority of the scheme of the present application: through the construction of the block structure, the s-TPI resin has excellent solubility, lower glass transition temperature, and the film has higher bonding performance.

[0363] In Comparative Examples 6-7, no monomer with a bulky functional group is used, and the solubility is very poor, significantly lower than that of Comparative Examples 1-5; this verifies the role of the bulky functional group in improving solubility. Moreover, Comparative Examples 6-7 do not use the block polymerization process, which is a commonly used homopolymerization production route, and the obtained polyimide resin does not have solubility and can only be coated using a polyamide acid solution. The subsequent high temperature imidization process cannot be avoided. The technical route of the present application realizes the production of a TPI composite film by dissolving and coating the soluble s-TPI resin, reduces the high temperature imidization step, and can significantly reduce the raw material cost, equipment cost and process cost.

[0364] Further, Comparative Examples 1-4. When the polymerization degree of the X segment increases, the heat resistance of the s-TPI resin increases, indicating that increasing the polymerization degree of the X block can continuously improve the heat resistance of the s-TPI resin. At the same time, the glass transition temperature of the s-TPI resin does not change, indicating that the polymerization degree of the X block has little effect on the flexibility of the molecular main chain, and the flexibility of the molecular main chain mainly depends on the number ratio and weight ratio of the polymerization units of the L segment in the molecular main chain. However, increasing the polymerization degree of the X segment will reduce the bonding strength of the s-TPI resin, indicating that the polymerization degree of the X segment should not be increased unlimitedly.

[0365] The number ratio of polymerized units of L segment in the molecular main chain of Examples 5-9 is higher than that of Examples 1-4. The number ratio of polymerized units of X segment is reduced, which results in the decrease of solubility of s-TPI resin in Examples 5-9; the increase of the number ratio of polymerized units of L segment is beneficial to the increase of flexibility of the molecular main chain, and the glass transition temperature of s-TPI resin in Examples 5-9 is obviously decreased. The total polymerization degree of s-TPI resin is changed in Examples 5-9, the length of molecular main chain is prolonged, the molecular weight is increased, and the heat resistance is significantly increased.

[0366] Examples 10-13 control the polymerization degree of X segment to be consistent, and change the polymerization degree and the number ratio of polymerized units of L segment in s-TPI resin. With the increase of the polymerization degree and the number ratio of polymerized units of L segment, the flexibility of the molecular main chain of s-TPI resin is continuously increased, and the glass transition temperature is continuously decreased. The increase of the flexibility of the molecular main chain also enhances the adhesive strength between s-TPI resin and copper foil. However, the polymerization degree of L segment should not be too large, and the number ratio of polymerized units should not be too high, otherwise, the solubility of s-TPI resin will be reduced.

[0367] Examples 14-18 change the proportion of high-flexibility dianhydride monomer used in L segment, and adjust the flexibility of L segment. With the increase of the proportion of high-flexibility dianhydride monomer, the flexibility of L segment is increased, the flexibility of the molecular main chain is increased, the glass transition temperature is continuously decreased, and the adhesive strength is increased. At the same time, due to the existence of X segment and the large total molecular main chain and polymerization degree, s-TPI resin still has strong solubility and good heat resistance.

[0368] In Comparative Examples 19-33, different dianhydride and diamine monomers are used to prepare X segment and L segment, and the proportion of high-flexibility dianhydride or diamine monomer used in L segment is also different. From the results of solubility, glass transition temperature and heat resistance, it can be seen that the difference of dianhydride and diamine monomers has little effect on the performance of s-TPI resin, and the performance of s-TPI resin depends more on the block, the polymerization degree of X segment and L segment, and the number ratio of polymerized units of L segment. The present application does not have high requirements for the specificity of dianhydride and diamine monomers, and can use more types of conventional and easily available dianhydride and diamine monomers for preparation.

Claims

1. A soluble thermoplastic polyimide resin, characterized in that, The molecular backbone of the soluble thermoplastic polyimide resin includes molecular chain segment L and molecular chain segment X; the molecular chain segment L has the molecular structure shown in Formula I, and the molecular chain segment X has the molecular structure shown in Formula II. In Equation I, 10 ≤ m ≤ 55; in Equation II, 3 ≤ n ≤ 10; Ar1 is selected from , , , , One of them; L1 is selected from , , , , , , One of them; and , , The molar ratio in Ar1 is 50-100%; B1 is selected from , , , , , , One of them; L2, L3, and L4 are each independently selected from single bonds, , , , , , , , One of them; Ar2 is selected from , , , One of them; B2 is selected from , , , , One of them; The molecular chain segments L and X are arranged alternately; The number of polymeric units in the molecular chain segment L accounts for 70-90% of the total number of polymeric units in the soluble thermoplastic polyimide resin molecular chain.

2. The soluble thermoplastic polyimide resin according to claim 1, characterized in that, Ar1 is selected from , , , , , , , , , , One of them; and , , The molar ratio in Ar1 is 50-100%; B1 is selected from , , , , , , , , , , , , , , , One of them.

3. The soluble thermoplastic polyimide resin according to claim 1, characterized in that, The total degree of polymerization of the molecular chain segment L and the molecular chain segment X is 100~650.

4. The soluble thermoplastic polyimide resin according to claim 1, characterized in that, The weight of the molecular chain segment L accounts for 60-90% of the total weight of the soluble thermoplastic polyimide resin molecular chain.

5. The soluble thermoplastic polyimide resin according to claim 1, characterized in that, The soluble thermoplastic polyimide resin has a solubility in a strongly polar solvent exceeding 10 g / 100 g of the strongly polar solvent; the strongly polar solvent is selected from one or more combinations of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, γ-butyrolactone, and m-cresol.

6. The soluble thermoplastic polyimide resin according to claim 1, characterized in that, The soluble thermoplastic polyimide resin has a glass transition temperature of 220~290℃ and / or a thermal decomposition temperature ≥ 450℃.

7. A method for preparing a soluble thermoplastic polyimide resin according to any one of claims 1 to 6, characterized in that, The preparation method includes: polymerizing diamine compound N2 and dianhydride compound G2 to form molecular chain segment X, and then adding diamine compound N1 and dianhydride compound G1 to polymerize to obtain the soluble thermoplastic polyimide resin; Wherein, the dianhydride compound G2 is a dianhydride having an Ar2 residue; the diamine compound N2 is a diamine having a B2 residue; the dianhydride compound G1 is a dianhydride having an Ar1 residue; and the diamine compound N1 is a diamine having a B1 residue.

8. The method for preparing the soluble thermoplastic polyimide resin according to claim 7, characterized in that, The preparation method includes the following steps: The dianhydride compound G2 is added to a solution containing the diamine compound N2 to carry out a first polymerization reaction, thereby obtaining a first product system; Remove the water generated in the first product system to obtain the second product system; The diamine compound N1 and the dianhydride compound G1 are added to the second product system to carry out a second polymerization reaction, thereby obtaining a third product system; The water generated in the third product system is removed to obtain the fourth product system. The soluble thermoplastic polyimide resin is precipitated from the fourth product system.

9. The method for preparing the soluble thermoplastic polyimide resin according to claim 8, characterized in that, The temperature of the first polymerization reaction and the second polymerization reaction are each independently 5~45℃, and the time is each independently 4~24h.

10. A thermoplastic polyimide coating, characterized in that, The thermoplastic polyimide coating comprises a strongly polar solvent and a soluble thermoplastic polyimide resin according to any one of claims 1 to 6.

11. The thermoplastic polyimide coating according to claim 10, characterized in that, The solid content of the thermoplastic polyimide coating is 8-20%.

12. The thermoplastic polyimide coating according to claim 10, characterized in that, The highly polar solvent is selected from one or more combinations of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and γ-butyrolactone.

13. A thermoplastic polyimide composite film, characterized in that, The thermoplastic polyimide composite film includes a polyimide film having a first surface and a second surface opposite to each other; a first coating and a second coating are respectively provided on the first surface and the second surface, and the first coating and the second coating are respectively obtained by coating and drying the coatings according to any one of claims 10 to 12.

14. A flexible copper-clad laminate, characterized in that, The flexible copper-clad laminate comprises a first copper foil, a thermoplastic polyimide composite film as described in claim 13, and a second copper foil, which are sequentially stacked.

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