Bending-resistant high-thermal-conductivity aluminum-based copper-clad plate and preparation method thereof

Abstract

The invention discloses a bending-resistant high-thermal-conductivity aluminum-based copper-clad plate and a preparation method thereof, and relates to the technical field of aluminum-based copper-clad plates. When the bending-resistant high-thermal-conductivity aluminum-based copper-clad plate is prepared, 2, 7-dinitro-9-fluorenone reacts with resorcinol, then nitro is converted into amino, and a modified monomer is prepared; polyimide monomers are polymerized and then react with 1-aminomethylmaleimide hydrochloride, and modified polyimide is prepared; the preparation method comprises the following steps: carrying out nitrogen treatment on an aluminum sheet, and then sequentially reacting with allyltrimethoxysilane, 4-(aminomethyl)-2-(tert-butyl) phenol, furan and 2-(2-chloroethyl), so as to prepare a functionalized aluminum sheet; the modified polyimide is subjected to thermal polymerization and then mixed with bisphenol A epoxy resin and acetone, rolled copper foil and the functionalized aluminum sheet are bonded and subjected to hot pressing, and the bending-resistant high-thermal-conductivity aluminum-based copper-clad plate is prepared. The bending-resistant high-thermal-conductivity aluminum-based copper-clad plate prepared by the invention has the effects that the insulating layer is waterproof, self-repairing, durable and high-temperature-resistant.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum-based copper clad laminates, and particularly to a bend-resistant and highly heat-conductive aluminum-based copper clad laminate and a preparation method thereof. Background Art

[0002] An aluminum-based copper clad laminate, i.e., an aluminum substrate, is a plate-like material made by impregnating an electronic glass fiber cloth or other reinforcing materials with a resin, a single resin, etc. as an insulating adhesive layer, and covering one or both sides with copper foil and then thermally pressing. It is called a copper-clad laminated aluminum substrate, abbreviated as an aluminum-based copper clad laminate. As a substrate material in the manufacture of printed circuit boards, it mainly plays the roles of interconnecting conduction, insulation, and support for printed circuit boards, and has a great influence on the signal transmission speed, energy loss, and characteristic impedance in the circuit. The performance, quality, processability, manufacturing level, manufacturing cost, and long-term reliability and stability of printed circuit boards largely depend on the aluminum-based copper clad laminate.

[0003] Aluminum-based copper clad laminates are widely used in the electronics industry, especially in occasions where good heat dissipation performance is required. Aluminum-based copper clad laminates are widely used in fields such as LED lighting products, power electronic devices, computers, and automotive electronics. In these applications, aluminum-based copper clad laminates often need to be bent to adapt to complex circuit designs and component layouts. Therefore, their bend resistance performance is crucial. Aluminum-based copper clad laminates transfer heat from heat-generating components to the aluminum substrate layer. If the heat conductivity is poor, it will cause local high temperatures, accelerating the aging or even burning of components, and a huge temperature difference is formed between the local high temperature and low temperature regions, generating thermal stress, resulting in the cracking of copper foil circuits or the delamination of the insulating layer. Therefore, this application introduces a bend-resistant and highly heat-conductive aluminum-based copper clad laminate and a preparation method thereof. Summary of the Invention

[0004] The purpose of the present invention is to provide a bend-resistant and highly heat-conductive aluminum-based copper clad laminate and a preparation method thereof to solve the problems existing in the prior art.

[0005] A bend-resistant and highly heat-conductive aluminum-based copper clad laminate is prepared by thermally polymerizing a modified polyimide, mixing it with bisphenol A epoxy resin and acetone, bonding a rolled copper foil and a functionalized aluminum sheet, and then thermally pressing.

[0006] The functionalized aluminum sheet is prepared by nitriding an aluminum sheet and then reacting it with allyltrimethoxysilane, 4-(aminomethyl)-2-(tert-butyl)phenol, and furan, 2-(2-chloroethyl) in sequence.

[0007] The modified polyimide is prepared by polymerizing a polyimide monomer and then reacting it with 1-aminomethyl maleimide hydrochloride.

[0008] The polyimide monomers are a modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, and 4-aminobenzonitrile respectively;

[0009] The modified monomer is prepared by first reacting 2,7-dinitro-9-fluorenone with resorcinol and then converting the nitro group into an amino group.

[0010] A preparation method of a bend-resistant and highly thermally conductive aluminum-based copper clad laminate. The preparation method of the bend-resistant and highly thermally conductive aluminum-based copper clad laminate mainly includes the following preparation steps:

[0011] (1) Mix pre-modified polyimide, 1-aminomethylmaleimide hydrochloride, and toluene according to a mass ratio of 4 - 6:20 - 30:1, stir at 150 - 170 °C and 200 - 300 r / min for 22 - 26 h, cool to room temperature, filter, wash with deionized water 3 - 5 times, and vacuum dry at 55 - 65 °C for 11 - 13 h to obtain modified polyimide;

[0012] (2) Mix furan, 2-(2-chloroethyl), dimethyl sulfoxide, and modified aluminum sheets according to a mass ratio of 1:8 - 12:3 - 5, ultrasonicate at 85 - 95 °C for 11 - 13 h, take out, wash with deionized water 3 - 5 times, and dry at 40 - 50 °C for 11 - 13 h to obtain functionalized aluminum sheets;

[0013] (3) Mix the modified polyimide and bisphenol A epoxy resin evenly according to a mass ratio of 1:4 - 6, coat it on the surface of a polypropylene film with a thickness of 48 - 52 μm, dry at 80 - 90 °C for 4.5 - 5.5 min, cool to room temperature, paste a rolled copper foil with a thickness of 0.6 mm on the surface, overmold at 115 - 125 °C for 3 - 5 min, remove the polypropylene film, paste the functionalized aluminum sheet, place it in a hot press, apply a pressure of 0.16 MPa, heat to 170 - 180 °C, keep warm for 80 - 100 min, and naturally cool to room temperature to obtain the aluminum-based copper clad laminate.

[0014] As an optimization, the pre-modified polyimide in step (1) is prepared by mixing the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline according to a molar ratio of 8 - 10:6 - 7:3 - 4:30 - 40:0.01, stirring at 200 - 300 r / min for 50 - 70 min, heating to 175 - 185 °C at a rate of 40 °C / h, stirring for 46 - 50 h, cooling to room temperature, adding 4-aminobenzonitrile in an amount 0.38 - 0.42 times the molar amount of the modified monomer, continuing to stir for 50 - 70 min, heating to 175 - 185 °C at a rate of 40 °C / h, stirring for 22 - 26 h, cooling to room temperature, pouring it into ethanol, filtering, washing with ethanol 3 - 5 times, and vacuum drying at 55 - 65 °C for 5 - 7 h.

[0015] As an optimization, the modified monomer is prepared by mixing ethanol and water evenly at a volume ratio of 2.8 - 3.2:1 to obtain an ethanol aqueous solution; mixing a pre-modified monomer, 200-mesh zinc powder, and ammonium chloride evenly at a molar ratio of 1:11 - 13:3.5 - 4.5, adding an ethanol aqueous solution 12 - 13 times the mass of the pre-modified monomer and glacial acetic acid 4.2 - 4.6 times the molar amount of the pre-modified monomer, stirring at 200 - 300 r / min, 58 - 62 °C under argon protection for 6 - 7 h, filtering, washing with deionized water 3 - 5 times, and vacuum drying at -10 - 0 °C for 22 - 26 h to obtain the modified monomer.

[0016] As an optimization, the pre-modified monomer is prepared by mixing 2,7-dinitro-9-fluorenone and resorcinol at a molar ratio of 1:2.4 - 2.6, adding p-toluenesulfonic acid 1.4 - 1.6 times the molar amount of 2,7-dinitro-9-fluorenone under argon protection, stirring at 200 - 300 r / min, 135 - 145 °C for 5 - 7 h, cooling to room temperature, adding methanol 4 - 5 times the molar amount of 2,7-dinitro-9-fluorenone, stirring at 200 - 300 r / min for 8 - 10 min, pouring into deionized water, standing for 20 - 30 min, filtering, washing with deionized water 3 - 5 times, and vacuum drying at -10 - 0 °C for 22 - 26 h.

[0017] As an optimization, the modified aluminum sheet in step (2) is prepared by mixing a pre-modified aluminum sheet, ethanol, and 4-(aminomethyl)-2-(tert-butyl)phenol at a mass ratio of 1:4 - 6:0.28 - 0.32, ultrasonicating at 45 - 55 °C under argon protection for 1.5 - 2.5 h, taking out, washing with deionized water 3 - 5 times, and drying at 40 - 50 °C for 11 - 13 h.

[0018] As an optimization, the pre-modified aluminum sheet is prepared by evenly applying a surface treatment solution on an aluminum sheet with an aluminum nitride layer on the surface, standing at 85 - 95 °C for 5 - 7 h, repeating the application and drying 5 times, washing with deionized water 6 - 8 times, and drying at 40 - 50 °C for 22 - 24 h.

[0019] As an optimization, the surface treatment solution is prepared by mixing allyltrimethoxysilane and isopropanol at a mass ratio of 1:8 - 12 and adjusting the pH to 4 - 6 with a 0.1 mol / L acetic acid aqueous solution.

[0020] As an optimization, the aluminum sheet with a surface aluminum nitride layer is obtained by successively polishing an aluminum sheet with a thickness of 1 mm using silicon carbide sandpapers of models P1000, P1500, and P2000 to 0.8 mm, polishing with W1 diamond polishing agent, ultrasonicating in ethanol for 8 - 12 min, vacuum drying at 50 - 60 °C for 6 - 8 h, placing it in a fully automatic pulsed power supply ion nitriding furnace, and the bombardment treatment parameters are: argon: hydrogen flow ratio is 1:1, bombardment temperature is 470 - 490 °C, bombardment time is 1 - 2 h; the nitriding process parameters are: nitrogen: hydrogen flow ratio is 2.8 - 3.2:1, furnace pressure is 260 - 270 Pa, temperature is 475 - 485 °C, and holding time is 23 - 25 h.

[0021] As an optimization, the adhesive in step (3) is prepared by mixing modified polyimide and N,N - dimethylacetamide in a mass ratio of 1:3 - 5, standing at 45 - 55 °C for 1.5 - 2.5 h, raising the temperature to 115 - 125 °C, standing for 1.5 - 2.5 h, ramping up the temperature at a rate of 40 °C / h to 375 - 385 °C, holding for 3.5 - 4.5 h, placing it in deionized water, cooling to room temperature, filtering, vacuum drying at - 10 - 0 °C for 22 - 26 h, and grinding to 400 mesh to obtain modified polyimide powder. Then, the modified polyimide powder, bisphenol A epoxy resin, and acetone are mixed evenly in a mass ratio of 18 - 22:78 - 82:5 - 7.

[0022] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0023] When preparing the bend - resistant and highly thermally conductive aluminum - based copper clad laminate, the present invention first reacts 2,7 - dinitro - 9 - fluorenone with resorcinol, and then converts the nitro group into an amino group to obtain a modified monomer; polymerizes the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′ - benzophenone tetracarboxylic dianhydride, and N - methylpyrrolidone and then reacts with 1 - aminomethylmaleimide hydrochloride to obtain a modified polyimide; nitride - treats the aluminum sheet and then reacts successively with allyltrimethoxysilane, 4 - (aminomethyl) - 2 - (tert - butyl)phenol, and furan,2 - (2 - chloroethyl) to obtain a functionalized aluminum sheet; thermally polymerizes the modified polyimide and then mixes it with bisphenol A epoxy resin and acetone, bonds the rolled copper foil and the functionalized aluminum sheet, and hot - presses to obtain the bend - resistant and highly thermally conductive aluminum - based copper clad laminate.

[0024] First, react 2,7-dinitro-9-fluorenone with resorcinol first, and then convert the nitro group to an amino group to obtain a modified monomer; polymerize the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, and N-methylpyrrolidone and then react with 1-aminomethylmaleimide hydrochloride to obtain a modified polyimide; react 2,7-dinitro-9-fluorenone with resorcinol first, and then convert the nitro group to an amino group to obtain a modified monomer containing a hydroxyl group, which can be used as a curing agent for epoxy resin; polymerize the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, and N-methylpyrrolidone to obtain a fluorine-containing polyimide, which can significantly reduce the surface tension of the adhesive, thereby achieving a waterproof effect, effectively preventing moisture from penetrating into the circuit board, protecting the circuit board from the erosion of a humid environment, preventing damage to electronic components by moisture, and avoiding the degradation of the electrical properties and material expansion of the circuit board; and polymaleimide can fill the microcracks and pores formed during the curing process of epoxy resin, reducing the diffusion path of corrosive media; then react with 1-aminomethylmaleimide hydrochloride to introduce maleimide, and through the DA reaction of maleimide with furan on the epoxy resin, form a cyclohexene with substituents, forming a thermally reversible dynamic covalent bond. The formation and breaking conditions of the bond are mild and there are few side reactions, so that the adhesive has a self-healing effect, automatically repairing tiny cracks and damages when the material is damaged, thereby reducing material failure caused by the accumulation of tiny damages and extending the service life of the material.

[0025] Secondly, nitride the aluminum sheet and then react it with allyltrimethoxysilane, 4-(aminomethyl)-2-(tert-butyl)phenol, and furan,2-(2-chloroethyl) in sequence to obtain a functionalized aluminum sheet; thermally polymerize the modified polyimide and then mix it with bisphenol A epoxy resin and acetone, bond the rolled copper foil and the functionalized aluminum sheet, and hot press to obtain a highly bend-resistant and highly thermally conductive aluminum-based copper clad laminate. Nitride the aluminum sheet to form a layer of aluminum nitride on the surface. Aluminum nitride can extremely improve the thermal conductivity of the material; then react with allyltrimethoxysilane and 4-(aminomethyl)-2-(tert-butyl)phenol to introduce a hindered phenol on the material surface. Due to the spatial hindrance of the hydroxyl group on the hindered phenol, the hydrogen atom is easily detached from the original molecular structure and combined with peroxy radicals, alkyl radicals, hydroxyl radicals, etc., causing it to lose its original activity, thereby terminating the oxygen aging reaction and extending the service life of the insulating layer; thermally polymerize the modified polyimide to form a triazine ring. The triazine ring has a highly planar and rigid structure. This structure makes the molecule not easily deformed at high temperatures, thereby maintaining the mechanical strength and stability of the material. Moreover, the carbon-nitrogen bond in the triazine ring is a relatively stable chemical bond, which can remain intact at high temperatures and is not easily broken. The stability of this bond further enhances the heat resistance of the insulating layer. Detailed implementation method

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] Embodiment 1:

[0028] A preparation method of a bend-resistant and highly thermally conductive aluminum-based copper clad laminate mainly includes the following preparation steps:

[0029] (1) Mix 2,7-dinitro-9-fluorenone and resorcinol at a molar ratio of 1:2.4. Under argon protection, add p-toluenesulfonic acid in an amount 1.4 times the molar amount of 2,7-dinitro-9-fluorenone. Stir at 200 r / min and 135 °C for 5 h, cool to room temperature, add methanol in an amount 4 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 200 r / min for 8 min, pour into deionized water, let stand for 20 min, filter, wash 3 times with deionized water, and vacuum dry at -10 °C for 22 h to obtain a pre-modified monomer;

[0030] Mix ethanol and water evenly at a volume ratio of 2.8:1 to obtain an ethanol aqueous solution; mix the pre-modified monomer, 200-mesh zinc powder, and ammonium chloride evenly at a molar ratio of 1:11:3.5, add an ethanol aqueous solution 12 times the mass of the pre-modified monomer and glacial acetic acid 4.2 times the molar amount of the pre-modified monomer, stir at 200 r / min, 58 °C under argon protection for 6 h, filter, wash 3 times with deionized water, and vacuum dry at -10 °C for 22 h to obtain a modified monomer;

[0031] Mix the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline at a molar ratio of 8:6:3:30:0.01, stir at 200 r / min for 50 min, heat up to 175 °C at a rate of 40 °C / h, stir for 46 h, cool to room temperature, add 4-aminobenzonitrile in an amount 0.38 times the molar amount of the modified monomer, continue to stir for 50 min, heat up to 175 °C at a rate of 40 °C / h, stir for 22 h, cool to room temperature, pour into ethanol, filter, wash 3 times with ethanol, and vacuum dry at 55 °C for 5 h to obtain a pre-modified polyimide;

[0032] Mix the pre-modified polyimide, 1-aminomethylmaleimide hydrochloride, and toluene at a mass ratio of 4:20:1, stir at 150 °C and 200 r / min for 22 h, cool to room temperature, filter, wash 3 times with deionized water, and vacuum dry at 55 °C for 11 h to obtain a modified polyimide;

[0033] (2) The aluminum sheet with a thickness of 1 mm was successively polished with silicon carbide sandpapers of models P1000, P1500, and P2000 to 0.8 mm, polished with W1 diamond polishing agent, ultrasonically treated in ethanol for 8 min, vacuum dried at 50 °C for 6 h, placed in a full-automatic pulse power ion nitriding furnace, and the bombardment treatment parameters were as follows: argon: hydrogen flow ratio was 1:1, bombardment temperature was 470 °C, and bombardment time was 1 h; the nitriding process parameters were as follows: nitrogen: hydrogen flow ratio was 2.8:1, furnace pressure was 260 Pa, temperature was 475 °C, and holding time was 23 h; an aluminum sheet with an aluminum nitride layer on the surface was obtained.

[0034] Allyltrimethoxysilane and isopropanol were mixed at a mass ratio of 1:8, and the pH was adjusted to 4 with 0.1 mol / L acetic acid aqueous solution to obtain a surface treatment solution. The surface treatment solution was evenly coated on the aluminum sheet with an aluminum nitride layer on the surface, left standing at 85 °C for 5 h, coated and dried 5 times repeatedly, washed 6 times with deionized water, and dried at 40 °C for 22 h to obtain a pre-modified aluminum sheet.

[0035] The pre-modified aluminum sheet, ethanol, and 4-(aminomethyl)-2-(tert-butyl)phenol were mixed at a mass ratio of 1:4:0.28, ultrasonically treated at 45 °C under argon protection for 1.5 h, taken out, washed 3 times with deionized water, and dried at 40 °C for 11 h to obtain a modified aluminum sheet.

[0036] Furan, 2-(2-chloroethyl), dimethyl sulfoxide, and the modified aluminum sheet were mixed at a mass ratio of 1:8:3, ultrasonically treated at 85 °C for 11 h, taken out, washed 3 times with deionized water, and dried at 40 °C for 11 h to obtain a functionalized aluminum sheet.

[0037] (3) The modified polyimide and N,N-dimethylacetamide were mixed at a mass ratio of 1:3, left standing at 45 °C for 1.5 h, heated to 115 °C, left standing for 1.5 h, heated at a programmed rate of 40 °C / h to 375 °C, held for 3.5 h, placed in deionized water, cooled to room temperature, filtered, vacuum dried at -10 °C for 22 h, and ground to 400 mesh to obtain modified polyimide powder. The modified polyimide powder, bisphenol A epoxy resin, and acetone were mixed evenly at a mass ratio of 18:78:5 to obtain an adhesive; the adhesive was coated on the surface of a polypropylene film with a thickness of 48 μm, dried at 80 °C for 4.5 min, cooled to room temperature, a rolled copper foil with a thickness of 0.6 mm was pasted on the surface, overmolded at 115 °C for 3 min, the polypropylene film was peeled off, the functionalized aluminum sheet was pasted on, placed in a hot press, pressurized at 0.16 MPa, heated to 170 °C, held for 80 min, and naturally cooled to room temperature to obtain an aluminum-based copper clad laminate.

[0038] Example 2:

[0039] A preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate mainly includes the following preparation steps:

[0040] (1) Mix 2,7-dinitro-9-fluorenone and resorcinol at a molar ratio of 1:2.5. Under argon protection, add p-toluenesulfonic acid in an amount 1.5 times the molar amount of 2,7-dinitro-9-fluorenone. Stir at 250 r / min and 140 °C for 6 h. Cool to room temperature, add methanol in an amount 4.5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 250 r / min for 9 min, pour into deionized water, let stand for 25 min, filter, wash 4 times with deionized water, and dry in vacuum at -5 °C for 24 h to obtain a pre-modified monomer.

[0041] Mix ethanol and water evenly at a volume ratio of 3:1 to obtain an ethanol aqueous solution. Mix the pre-modified monomer, 200-mesh zinc powder, and ammonium chloride evenly at a molar ratio of 1:12:4. Add an ethanol aqueous solution 12.5 times the mass of the pre-modified monomer and glacial acetic acid in an amount 4.4 times the molar amount of the pre-modified monomer. Stir at 250 r / min, 60 °C under argon protection for 6.5 h, filter, wash 4 times with deionized water, and dry in vacuum at -5 °C for 24 h to obtain a modified monomer.

[0042] Mix the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline at a molar ratio of 9:6.5:3.5:35:0.01. Stir at 250 r / min for 60 min, heat up to 180 °C at a rate of 40 °C / h, stir for 48 h, cool to room temperature, add 4-aminobenzonitrile in an amount 0.4 times the molar amount of the modified monomer, continue to stir for 60 min, heat up to 180 °C at a rate of 40 °C / h, stir for 24 h, cool to room temperature, pour into ethanol, filter, wash 4 times with ethanol, and dry in vacuum at 60 °C for 6 h to obtain a pre-modified polyimide.

[0043] Mix the pre-modified polyimide, 1-aminomethylmaleimide hydrochloride, and toluene at a mass ratio of 5:25:1. Stir at 160 °C and 250 r / min for 24 h, cool to room temperature, filter, wash 4 times with deionized water, and dry in vacuum at 60 °C for 12 h to obtain a modified polyimide.

[0044] (2) Polish an aluminum sheet with a thickness of 1 mm successively using silicon carbide sandpapers of models P1000, P1500, and P2000 to 0.8 mm, polish with W1 diamond polishing agent, ultrasonically clean in ethanol for 10 min, dry in vacuum at 55 °C for 7 h, place in a full-automatic pulsed power ion nitriding furnace. Bombardment treatment parameters: argon:hydrogen flow ratio is 1:1, bombardment temperature is 480 °C, bombardment time is 1.5 h; nitriding process parameters: nitrogen:hydrogen flow ratio is 3:1, furnace pressure is 265 Pa, temperature is 480 °C, holding time is 24 h; obtain an aluminum sheet with an aluminum nitride layer on the surface.

[0045] Mix allyltrimethoxysilane and isopropanol at a mass ratio of 1:10, adjust the pH to 5 with 0.1 mol / L aqueous acetic acid solution to obtain a surface treatment solution. Apply the surface treatment solution evenly on an aluminum sheet with an aluminum nitride layer on its surface, let it stand at 90 °C for 6 h, repeat the application and drying 5 times, wash it 7 times with deionized water, and dry it at 45 °C for 23 h to obtain a pre-modified aluminum sheet;

[0046] Mix the pre-modified aluminum sheet, ethanol and 4-(aminomethyl)-2-(tert-butyl)phenol at a mass ratio of 1:5:0.3, under the protection of argon at 50 °C, ultrasonicate for 2 h, take it out, wash it 4 times with deionized water, and dry it at 45 °C for 12 h to obtain a modified aluminum sheet;

[0047] Mix furan, 2-(2-chloroethyl), dimethyl sulfoxide and the modified aluminum sheet at a mass ratio of 1:10:4, ultrasonicate at 90 °C for 12 h, take it out, wash it 4 times with deionized water, and dry it at 45 °C for 12 h to obtain a functionalized aluminum sheet;

[0048] (3) Mix the modified polyimide and N,N-dimethylacetamide at a mass ratio of 1:4, let it stand at 50 °C for 2 h, raise the temperature to 120 °C and let it stand for 2 h, then heat it at a programmed rate of 40 °C / h to 380 °C and hold for 4 h. Place it in deionized water, cool to room temperature, filter, vacuum dry at -5 °C for 24 h, and grind to 400 mesh to obtain modified polyimide powder. Mix the modified polyimide powder, bisphenol A epoxy resin and acetone evenly at a mass ratio of 20:80:5 to obtain an adhesive. Coat the adhesive on the surface of a polypropylene film with a thickness of 50 μm, dry it at 85 °C for 5 min, cool to room temperature, paste a rolled copper foil with a thickness of 0.6 mm on the surface, laminate it at 120 °C for 4 min, remove the polypropylene film, paste the functionalized aluminum sheet, place it in a hot press and apply a pressure of 0.16 MPa, heat to 175 °C, keep warm for 90 min, and naturally cool to room temperature to obtain an aluminum-based copper clad laminate.

[0049] Example 3:

[0050] A preparation method of a bend-resistant and high thermal conductivity aluminum-based copper clad laminate mainly includes the following preparation steps:

[0051] (1) Mix 2,7-dinitro-9-fluorenone and resorcinol at a molar ratio of 1:2.6. Under the protection of argon, add p-toluenesulfonic acid in an amount 1.6 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 300 r / min and 145 °C for 7 h, cool to room temperature, add methanol in an amount 5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 300 r / min for 10 min, pour it into deionized water, let it stand for 30 min, filter, wash it 5 times with deionized water, and vacuum dry at 0 °C for 26 h to obtain a pre-modified monomer;

[0052] Mix ethanol and water evenly at a volume ratio of 3.2:1 to obtain an ethanol aqueous solution; mix the pre-modified monomer, 200-mesh zinc powder, and ammonium chloride evenly at a molar ratio of 1:13:4.5, add an ethanol aqueous solution 13 times the mass of the pre-modified monomer and glacial acetic acid 4.6 times the molar amount of the pre-modified monomer, stir at 300 r / min, 62 °C under argon protection for 7 h, filter, wash with deionized water 5 times, and vacuum dry at 0 °C for 26 h to obtain the modified monomer;

[0053] Mix the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline at a molar ratio of 10:7:4:40:0.01, stir at 300 r / min for 70 min, heat up to 185 °C at a rate of 40 °C / h, stir for 50 h, cool to room temperature, add 4-aminobenzonitrile 0.42 times the molar amount of the modified monomer, continue to stir for 70 min, heat up to 185 °C at a rate of 40 °C / h, stir for 26 h, cool to room temperature, pour into ethanol, filter, wash with ethanol 5 times, and vacuum dry at 65 °C for 7 h to obtain the pre-modified polyimide;

[0054] Mix the pre-modified polyimide, 1-aminomethylmaleimide hydrochloride, and toluene at a mass ratio of 6:30:1, stir at 170 °C, 300 r / min for 26 h, cool to room temperature, filter, wash with deionized water 5 times, and vacuum dry at 65 °C for 13 h to obtain the modified polyimide;

[0055] (2)Sand an aluminum sheet with a thickness of 1 mm successively using silicon carbide sandpapers of models P1000, P1500, and P2000 to 0.8 mm, polish with W1 diamond polishing agent, ultrasonicate in ethanol for 12 min, vacuum dry at 60 °C for 8 h, place in a fully automatic pulsed power supply ion nitriding furnace, bombardment treatment parameters: argon:hydrogen flow ratio is 1:1, bombardment temperature is 490 °C, bombardment time is 2 h; nitriding process parameters: nitrogen:hydrogen flow ratio is 3.2:1, furnace pressure: 270 Pa, temperature is 485 °C, holding time is 25 h; obtain an aluminum sheet with an aluminum nitride layer on the surface;

[0056] Mix allyltrimethoxysilane and isopropanol at a mass ratio of 1:12, adjust the pH to 6 with 0.1 mol / L acetic acid aqueous solution to obtain a surface treatment solution, evenly apply the surface treatment solution on the aluminum sheet with an aluminum nitride layer on the surface, let stand at 95 °C for 7 h, repeat the application and drying 5 times, wash with deionized water 8 times, and dry at 50 °C for 24 h to obtain the pre-modified aluminum sheet;

[0057] Mix pre-modified aluminum sheets, ethanol, and 4-(aminomethyl)-2-(tert-butyl)phenol in a mass ratio of 1:6:0.32, ultrasound for 2.5 h at 55 °C under argon protection, take out, wash 5 times with deionized water, and dry at 50 °C for 13 h to obtain modified aluminum sheets;

[0058] Mix furan, 2-(2-chloroethyl), dimethyl sulfoxide, and modified aluminum sheets in a mass ratio of 1:12:5, ultrasound for 13 h at 95 °C, take out, wash 5 times with deionized water, and dry at 50 °C for 13 h to obtain functionalized aluminum sheets;

[0059] (3) Mix modified polyimide and N,N-dimethylacetamide in a mass ratio of 1:5, let stand at 55 °C for 2.5 h, raise the temperature to 125 °C, let stand for 2.5 h, program the temperature to 385 °C at 40 °C / h, hold for 4.5 h, place in deionized water, cool to room temperature, filter, vacuum dry at 0 °C for 26 h, grind to 400 mesh to obtain modified polyimide powder. Mix the modified polyimide powder, bisphenol A epoxy resin, and acetone evenly in a mass ratio of 22:82:7 to obtain an adhesive; coat the adhesive on the surface of a polypropylene film with a thickness of 52 μm, dry at 90 °C for 5.5 min, cool to room temperature, paste a rolled copper foil with a thickness of 0.6 mm on the surface, laminate at 125 °C for 5 min, remove the polypropylene film, stick on the functionalized aluminum sheet, place in a hot press, apply a pressure of 0.16 MPa, heat to 180 °C, keep warm for 100 min, and naturally cool to room temperature to obtain an aluminum-based copper clad laminate.

[0060] Comparative Example 1:

[0061] The preparation method of the high bending resistance and high thermal conductivity aluminum-based copper clad laminate in Comparative Example 1 is different from that in Example 2 in step (1). Modify step (1) as follows: Mix 2,7-dinitro-9-fluorenone and resorcinol in a molar ratio of 1:2.5, under argon protection, add p-toluenesulfonic acid in an amount 1.5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 250 r / min and 140 °C for 6 h, cool to room temperature, add methanol in an amount 4.5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 250 r / min for 9 min, pour into deionized water, let stand for 25 min, filter, wash 4 times with deionized water, and vacuum dry at -5 °C for 24 h to obtain a pre-modified monomer;

[0062] Mix ethanol and water evenly at a volume ratio of 3:1 to obtain an ethanol aqueous solution; mix the pre-modified monomer, 200-mesh zinc powder, and ammonium chloride evenly at a molar ratio of 1:12:4, add an ethanol aqueous solution 12.5 times the mass of the pre-modified monomer and glacial acetic acid 4.4 times the molar amount of the pre-modified monomer, and stir at 250 r / min, 60 °C under argon protection for 6.5 h, filter, wash 4 times with deionized water, and vacuum dry at -5 °C for 24 h to obtain the modified monomer;

[0063] Mix the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline at a molar ratio of 9:6.5:3.5:35:0.01, stir at 250 r / min for 60 min, heat up to 180 °C at 40 °C / h, stir for 48 h, cool to room temperature, add 4-aminobenzonitrile 0.4 times the molar amount of the modified monomer, continue to stir for 60 min, heat up to 180 °C at 40 °C / h, stir for 24 h, cool to room temperature, pour into ethanol, filter, wash 4 times with ethanol, and vacuum dry at 60 °C for 6 h to obtain the modified polyimide. The remaining steps are the same as in Example 2.

[0064] Comparative Example 2:

[0065] The difference between the preparation method of the bend-resistant high thermal conductivity aluminum-based copper clad laminate in Comparative Example 2 and that in Example 2 lies in the difference in step (1). Modify step (1) as follows: Mix 2,7-dinitro-9-fluorenone and resorcinol at a molar ratio of 1:2.5, under argon protection, add p-toluenesulfonic acid 1.5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 250 r / min, 140 °C for 6 h, cool to room temperature, add methanol 4.5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 250 r / min for 9 min, pour into deionized water, let stand for 25 min, filter, wash 4 times with deionized water, and vacuum dry at -5 °C for 24 h to obtain the pre-modified monomer;

[0066] Mix ethanol and water evenly at a volume ratio of 3:1 to obtain an ethanol aqueous solution; mix the pre-modified monomer, 200-mesh zinc powder, and ammonium chloride evenly at a molar ratio of 1:12:4, add an ethanol aqueous solution 12.5 times the mass of the pre-modified monomer and glacial acetic acid 4.4 times the molar amount of the pre-modified monomer, and stir at 250 r / min, 60 °C under argon protection for 6.5 h, filter, wash 4 times with deionized water, and vacuum dry at -5 °C for 24 h to obtain the modified monomer;

[0067] Mix the modified monomer, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline in a molar ratio of 9:10:35:0.01, stir at 250 r / min for 60 min, heat to 180 °C at a rate of 40 °C / h, stir for 48 h, cool to room temperature, add 4-aminobenzonitrile in an amount 0.4 times the molar amount of the modified monomer, continue to stir for 60 min, heat to 180 °C at a rate of 40 °C / h, stir for 24 h, cool to room temperature, pour into ethanol, filter, wash 4 times with ethanol, and dry in vacuo at 60 °C for 6 h to obtain the modified polyimide. The remaining steps are the same as in Example 2.

[0068] Comparative Example 3:

[0069] The difference between the preparation method of the high-flexure-resistant and high-thermal-conductivity aluminum-based copper clad laminate of Comparative Example 3 and that of Example 2 lies in step (2). Modify step (2) as follows: Grind an aluminum sheet with a thickness of 1 mm successively with silicon carbide sandpapers of grades P1000, P1500, and P2000 to 0.8 mm, polish with W1 diamond polishing agent, ultrasonicate in ethanol for 10 min, dry in vacuo at 55 °C for 7 h, place in a full-automatic pulsed power ion nitriding furnace, and the bombardment treatment parameters are as follows: argon:hydrogen flow ratio is 1:1, bombardment temperature is 480 °C, and bombardment time is 1.5 h; the nitriding process parameters are as follows: nitrogen:hydrogen flow ratio is 3:1, furnace pressure is 265 Pa, temperature is 480 °C, and holding time is 24 h; to obtain an aluminum sheet with an aluminum nitride layer on the surface;

[0070] Mix allyltrimethoxysilane and isopropanol in a mass ratio of 1:10, adjust the pH to 5 with 0.1 mol / L aqueous acetic acid solution to obtain a surface treatment solution. Apply the surface treatment solution evenly on the aluminum sheet with an aluminum nitride layer on the surface, let stand at 90 °C for 6 h, repeat the application and drying 5 times, wash 7 times with deionized water, and dry at 45 °C for 23 h to obtain a pre-modified aluminum sheet;

[0071] Mix the pre-modified aluminum sheet, ethanol, and 4-(aminomethyl)-2-(tert-butyl)phenol in a mass ratio of 1:5:0.3, ultrasonicate at 50 °C under argon protection for 2 h, take out, wash 4 times with deionized water, and dry at 45 °C for 12 h to obtain a functionalized aluminum sheet. The remaining steps are the same as in Example 2.

[0072] Comparative Example 4:

[0073] The preparation method of the bend-resistant and highly heat-conductive aluminum-based copper clad laminate of Comparative Example 4 is different from that of Example 2 in step (2). Step (2) is modified as follows: An aluminum sheet with a thickness of 1 mm is successively polished with silicon carbide sandpapers of models P1000, P1500, and P2000 to 0.8 mm, polished with W1 diamond polishing agent, ultrasonically treated in ethanol for 10 min, vacuum dried at 55 °C for 7 h, and placed in a fully automatic pulsed power supply ion nitriding furnace. The bombardment treatment parameters are as follows: argon: hydrogen flow ratio is 1:1, bombardment temperature is 480 °C, and bombardment time is 1.5 h; the nitriding process parameters are as follows: nitrogen: hydrogen flow ratio is 3:1, furnace pressure is 265 Pa, temperature is 480 °C, and holding time is 24 h; a functionalized aluminum sheet is obtained. The remaining steps are the same as those in Example 2.

[0074] Comparative Example 5:

[0075] The preparation method of the bend-resistant and highly heat-conductive aluminum-based copper clad laminate of Comparative Example 5 is different from that of Example 2 in step (2). Step (2) is modified as follows: An aluminum sheet with a thickness of 1 mm is successively polished with silicon carbide sandpapers of models P1000, P1500, and P2000 to 0.8 mm, polished with W1 diamond polishing agent, ultrasonically treated in ethanol for 10 min, vacuum dried at 55 °C for 7 h, and a functionalized aluminum sheet is obtained. The remaining steps are the same as those in Example 2.

[0076] Comparative Example 6:

[0077] The preparation method of the bend-resistant and highly thermally conductive aluminum-based copper clad laminate of Comparative Example 6 is different from that of Example 2 in steps (1) and (3). Modify step (1) as follows: Mix 2,7-dinitro-9-fluorenone and resorcinol in a molar ratio of 1:2.5. Under argon protection, add p-toluenesulfonic acid in an amount 1.5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 250 r / min and 140 °C for 6 h, cool to room temperature, add methanol in an amount 4.5 times the molar amount of 2,7-dinitro-9-fluorenone, stir at 250 r / min for 9 min, pour into deionized water, let stand for 25 min, filter, wash 4 times with deionized water, and vacuum dry at -5 °C for 24 h to obtain a pre-modified monomer; Mix ethanol and water evenly at a volume ratio of 3:1 to obtain an ethanol aqueous solution; Mix the pre-modified monomer, 200-mesh zinc powder, and ammonium chloride evenly in a molar ratio of 1:12:4, add an ethanol aqueous solution 12.5 times the mass of the pre-modified monomer and glacial acetic acid in an amount 4.4 times the molar amount of the pre-modified monomer, stir at 250 r / min, 60 °C under argon protection for 6.5 h, filter, wash 4 times with deionized water, and vacuum dry at -5 °C for 24 h to obtain a modified monomer; Mix the modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline in a molar ratio of 9:6.5:3.5:35:0.01, stir at 250 r / min for 60 min, heat up to 180 °C at a rate of 40 °C / h, stir for 48 h, cool to room temperature, add aniline in an amount 0.4 times the molar amount of the modified monomer, continue to stir for 60 min, heat up to 180 °C at a rate of 40 °C / h, stir for 24 h, cool to room temperature, pour into ethanol, filter, wash 4 times with ethanol, and vacuum dry at 60 °C for 6 h to obtain a pre-modified polyimide; Mix the pre-modified polyimide, 1-aminomethylmaleimide hydrochloride, and toluene in a mass ratio of 5:25:1, stir at 160 °C and 250 r / min for 24 h, cool to room temperature, filter, wash 4 times with deionized water, and vacuum dry at 60 °C for 12 h to obtain a modified polyimide; Modify step (3) to grind the modified polyimide to 400 mesh to obtain a modified polyimide powder. Mix the modified polyimide powder, bisphenol A epoxy resin, and acetone evenly in a mass ratio of 20:80:5 to obtain an adhesive; Coat the adhesive on the surface of a polypropylene film with a thickness of 50 μm, dry at 85 °C for 5 min, cool to room temperature, paste a rolled copper foil with a thickness of 0.6 mm on the surface, overmold at 120 °C for 4 min, remove the polypropylene film, stick on a functionalized aluminum sheet, place in a hot press and apply pressure of 0.16 MPa, heat to 175 °C, keep warm for 90 min, and naturally cool to room temperature to obtain an aluminum-based copper clad laminate. The remaining steps are the same as those in Example 2.

[0078] Test Example 1:

[0079] Bend resistance test:

[0080] Test method: Test according to the IPC-TM-650 2.4.3 test standard. The results are shown in Table 1.

[0081] Table 1

[0082] Folding resistance Example 1 > 10 times Example 2 > 10 times Example 3 > 10 times Comparative Example 1 > 10 times Comparative Example 2 > 10 times Comparative Example 3 > 10 times Comparative Example 4 > 10 times Comparative Example 5 > 10 times Comparative Example 6 > 10 times

[0083] From the comparison of the experimental data in Table 1, it can be found that the bend-resistant and high-thermal-conductivity aluminum-based copper clad laminate prepared by the present invention has good bend resistance.

[0084] Test Example 2:

[0085] Thermal conductivity test:

[0086] Test method: Test according to ASTM D5470. The results are shown in Table 2.

[0087] Table 2

[0088] Thermal conductivity Example 1 3.38 W / m·K Example 2 3.40 W / m·K Example 3 3.41 W / m·K Comparative Example 1 3.39 W / m·K Comparative Example 2 3.37 W / m·K Comparative Example 3 3.36 W / m·K Comparative Example 4 3.38 W / m·K Comparative Example 5 1.98 W / m·K Comparative Example 6 3.39 W / m·K

[0089] From the comparison of the experimental data in Table 2, it can be found that the bend-resistant and high-thermal-conductivity aluminum-based copper clad laminate prepared by the present invention has good thermal conductivity.

[0090] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 5 in Table 2, it can be found that the thermal conductivity coefficients of Examples 1, 2 and 3 are large. The difference between Comparative Example 5 and the examples is that aluminum nitride is not formed on the surface of the aluminum plate, indicating that aluminum nitride can extremely improve the thermal conductivity of the material.

[0091] Test Example 3:

[0092] Insulating layer test:

[0093] Evenly apply the adhesives prepared in each example and comparative example on the polytetrafluoroethylene plate with a thickness of 50 μm, a length of 15 cm and a width of 3 cm, cure at 85 °C, peel off and test;

[0094] Aging resistance test: Test the tensile strength of the test specimen, denoted as J0. Age the specimen for three days at a temperature of 70 °C and a humidity of 100%, and then test the tensile strength again, denoted as J1. The aging retention rate = J1 / J0×100%;

[0095] Self-healing test: Test the tensile strength of the test specimen, denoted as J0. Make a transverse cut with a length of 2 cm and a depth of 50 μm in the center of the specimen, let it stand at 80 °C for 24 h, cool to room temperature, and then test the tensile strength again, denoted as J2. The self-healing rate = J2 / J0×100%;

[0096] Waterproof test: Test the water contact angle;

[0097] High-temperature resistance test: The test was carried out using a TA Instruments Q500 thermogravimetric analyzer. Under a nitrogen atmosphere, the temperature was raised from room temperature to 120 °C at a heating rate of 20 °C / min, held for 20 min, then cooled to 100 °C, and the second heating was carried out. The temperature was raised from 100 °C to 800 °C at a rate of 20 °C / min, and the nitrogen flow rate was 50 mL / min. The 5% thermal weight loss temperature was recorded. The results are shown in Table 3.

[0098] Table 3

[0099] Aging retention rate Self-healing rate Water contact angle 5% Thermal weight loss temperature Example 1 98.8% 98.3% 108.3° 410.3℃ Example 2 99.0% 98.1% 108.6° 411.0℃ Example 3 98.9% 98.4% 108.5° 410.7℃ Comparative Example 1 98.6% 39.6% 108.4° 410.6℃ Comparative Example 2 98.7% 39.8% 89.2° 411.1℃ Comparative Example 3 98.5% 39.7% 108.2° 410.5℃ Comparative Example 4 96.2% 39.5% 108.3° 410.1℃ Comparative Example 5 96.1% 39.3% 108.5° 410.2℃ Comparative Example 6 98.7% 98.2% 108.2° 353.5℃

[0100] From the comparison of the experimental data in Table 3, it can be found that the insulating layer of the bend-resistant and highly thermally conductive aluminum-based copper clad laminate prepared by the present invention has good aging resistance, self-healing, heat resistance and waterproofing capabilities.

[0101] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 1 in Table 3, it can be found that the self-healing rates of Examples 1, 2, 3 are large. The difference between Comparative Example 1 and the examples is that maleimide structure is not introduced into the polyimide, and it cannot undergo a DA reaction with furan, indicating that through the DA reaction of maleimide with furan on the epoxy resin, cyclohexene with substituents can be formed, forming thermally reversible dynamic covalent bonds. The formation and breaking conditions of the bonds are mild and the side reactions are few, so that the insulating layer has a self-healing effect;

[0102] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 2, it can be found that the water contact angles of Examples 1, 2, 3 are large. The difference between Comparative Example 2 and the examples is that fluorine is not added to the main chain in the polyimide, indicating that adding fluorinated polyimide can significantly reduce the surface tension of the insulating layer, thus achieving a waterproof effect;

[0103] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 4, it can be found that the aging retention rates of Examples 1, 2, 3 are large. The difference between Comparative Example 4 and the examples is that hindered phenol is not introduced on the aluminum plate surface, indicating that the hydroxyl group on the hindered phenol is restricted by steric hindrance, and the hydrogen atom is easily detached from the original molecular structure and combined with peroxy radicals, alkyl radicals, hydroxyl radicals, etc., resulting in the loss of its original activity, thus terminating the oxygen aging reaction and prolonging the service life of the insulating layer;

[0104] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 6, it can be found that the aging retention rates of Examples 1, 2, and 3 are large. The difference between Comparative Example 6 and the examples is that the benzonitrile at both ends of the polyimide is not reacted to form a triazine, indicating that the triazine ring has a highly planar and rigid structure. This structure makes the molecules not easily deformed at high temperatures, thereby maintaining the mechanical strength and stability of the material. Moreover, the carbon-nitrogen bond in the triazine ring is a relatively stable chemical bond that can remain intact at high temperatures and is not easily broken. The stability of this bond further enhances the heat resistance of the insulating layer.

[0105] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bend-resistant and highly thermally conductive aluminum-based copper clad laminate, characterized in that, The bend-resistant and highly thermally conductive aluminum-based copper clad laminate is prepared by thermally polymerizing modified polyimide, mixing it with bisphenol A epoxy resin and acetone, bonding rolled copper foil and functionalized aluminum sheet, and then hot pressing; The functionalized aluminum sheet is prepared by nitriding an aluminum sheet and then reacting it successively with allyltrimethoxysilane, 4-(aminomethyl)-2-(tert-butyl)phenol, and furan, 2-(2-chloroethyl); The modified polyimide is prepared by polymerizing polyimide monomers and then reacting them with 1-aminomethyl maleimide hydrochloride; The polyimide monomers are a modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, and 4-aminobenzonitrile respectively; The modified monomer is prepared by first reacting 2,7-dinitro-9-fluorenone with resorcinol and then converting the nitro group to an amino group; 2. A preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate, characterized in that, The preparation method of the bend-resistant and highly thermally conductive aluminum-based copper clad laminate mainly includes the following preparation steps: (1) Mix pre-modified polyimide, 1-aminomethyl maleimide hydrochloride, and toluene in a mass ratio of 4-6: 20-30: 1, stir at 150-170 °C and 200-300 r / min for 22-26 h, cool to room temperature, filter, wash with deionized water 3-5 times, and vacuum dry at 55-65 °C for 11-13 h to obtain modified polyimide; (2) Mix furan, 2-(2-chloroethyl), dimethyl sulfoxide, and modified aluminum sheet in a mass ratio of 1: 8-12: 3-5, ultrasonicate at 85-95 °C for 11-13 h, take out, wash with deionized water 3-5 times, and dry at 40-50 °C for 11-13 h to obtain functionalized aluminum sheet; (3) Coat the adhesive on the surface of a polypropylene film with a thickness of 48-52 μm, dry at 80-90 °C for 4.5-5.5 min, cool to room temperature, paste a rolled copper foil with a thickness of 0.6 mm on the surface, overmold at 115-125 °C for 3-5 min, remove the polypropylene film, paste the functionalized aluminum sheet, place it in a hot press, apply a pressure of 0.16 MPa, heat to 170-180 °C, keep warm for 80-100 min, and naturally cool to room temperature to obtain the aluminum-based copper clad laminate.

3. The preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate according to claim 2, characterized in that, The pre-modified polyimide in step (1) is prepared by mixing a modified monomer, diphenylhexafluoroisopropyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, N-methylpyrrolidone, and isoquinoline in a molar ratio of 8-10: 6-7: 3-4: 30-40: 0.01, stirring at 200-300 r / min for 50-70 min, heating to 175-185 °C at a rate of 40 °C / h, stirring for 46-50 h, cooling to room temperature, adding 4-aminobenzonitrile in an amount 0.38-0.42 times the molar amount of the modified monomer, continuing to stir for 50-70 min, heating to 175-185 °C at a rate of 40 °C / h, stirring for 22-26 h, cooling to room temperature, pouring into ethanol, filtering, washing with ethanol 3-5 times, and vacuum drying at 55-65 °C for 5-7 h.

4. The preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate according to claim 3, characterized in that, The modified monomer is prepared by mixing ethanol and water in a volume ratio of 2.8 - 3.2:1 to obtain an ethanol aqueous solution; mixing a pre-modified monomer, 200-mesh zinc powder, and ammonium chloride in a molar ratio of 1:11 - 13:3.5 - 4.5, adding an ethanol aqueous solution 12 - 13 times the mass of the pre-modified monomer and glacial acetic acid 4.2 - 4.6 times the molar amount of the pre-modified monomer, stirring at 200 - 300 r / min, 58 - 62 °C under argon protection for 6 - 7 h, filtering, washing with deionized water 3 - 5 times, and vacuum drying at -10 - 0 °C for 22 - 26 h to obtain the modified monomer.

5. The preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate according to claim 4, characterized in that, The pre-modified monomer is prepared by mixing 2,7-dinitro-9-fluorenone and resorcinol in a molar ratio of 1:2.4 - 2.6, adding p-toluenesulfonic acid 1.4 - 1.6 times the molar amount of 2,7-dinitro-9-fluorenone under argon protection, stirring at 200 - 300 r / min, 135 - 145 °C for 5 - 7 h, cooling to room temperature, adding methanol 4 - 5 times the molar amount of 2,7-dinitro-9-fluorenone, stirring at 200 - 300 r / min for 8 - 10 min, pouring into deionized water, standing for 20 - 30 min, filtering, washing with deionized water 3 - 5 times, and vacuum drying at -10 - 0 °C for 22 - 26 h.

6. The preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate according to claim 2, characterized in that, The modified aluminum sheet in step (2) is prepared by mixing a pre-modified aluminum sheet, ethanol, and 4-(aminomethyl)-2-(tert-butyl)phenol in a mass ratio of 1:4 - 6:0.28 - 0.32, ultrasonicating at 45 - 55 °C under argon protection for 1.5 - 2.5 h, taking out, washing with deionized water 3 - 5 times, and drying at 40 - 50 °C for 11 - 13 h.

7. The preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate according to claim 6, characterized in that, The pre-modified aluminum sheet is prepared by evenly applying a surface treatment liquid on an aluminum sheet with an aluminum nitride layer on the surface, standing at 85 - 95 °C for 5 - 7 h, repeating the application and drying 5 times, washing with deionized water 6 - 8 times, and drying at 40 - 50 °C for 22 - 24 h.

8. The preparation method of a bend-resistant and highly thermally conductive aluminum-based copper clad laminate according to claim 7, characterized in that The surface treatment liquid is prepared by mixing allyltrimethoxysilane and isopropanol in a mass ratio of 1:8 - 12 and adjusting the pH to 4 - 6 with a 0.1 mol / L acetic acid aqueous solution.

9. The preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate according to claim 7, wherein, The aluminum sheet with an aluminum nitride layer on the surface is prepared by successively polishing an aluminum sheet with a thickness of 1 mm using silicon carbide sandpapers of models P1000, P1500, and P2000 to 0.8 mm, polishing with W1 diamond polishing agent, ultrasonicating in ethanol for 8 - 12 min, vacuum drying at 50 - 60 °C for 6 - 8 h, placing in a full-automatic pulsed power supply ion nitriding furnace, with bombardment treatment parameters: argon:hydrogen flow ratio of 1:1, bombardment temperature of 470 - 490 °C, bombardment time of 1 - 2 h; nitriding process parameters: nitrogen:hydrogen flow ratio of 2.8 - 3.2:1, furnace pressure of 260 - 270 Pa, temperature of 475 - 485 °C, and holding time of 23 - 25 h.

10. The preparation method of a bend-resistant and highly heat-conductive aluminum-based copper clad laminate according to claim 2, wherein, The adhesive described in step (3) is prepared by mixing modified polyimide and N,N-dimethylacetamide in a mass ratio of 1:3 to 5, standing at 45 to 55 °C for 1.5 to 2.5 h, raising the temperature to 115 to 125 °C, standing for 1.5 to 2.5 h, heating at a programmed rate of 40 °C / h to 375 to 385 °C, holding for 3.5 to 4.5 h, placing in deionized water, cooling to room temperature, filtering, vacuum drying at -10 to 0 °C for 22 to 26 h, grinding to 400 mesh to obtain modified polyimide powder, and then mixing the modified polyimide powder, bisphenol A epoxy resin and acetone evenly in a mass ratio of 18 to 22:78 to 82:5 to 7.