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CN-121405880-B - Polyimide precursor and polyimide with low water absorption rate, and preparation methods and applications thereof

CN121405880BCN 121405880 BCN121405880 BCN 121405880BCN-121405880-B

Abstract

The invention provides a polyimide precursor with low water absorption rate, polyimide and a preparation method and application thereof, wherein the invention firstly synthesizes a PAA chain segment, then copolymerizing with olefin monomer containing alicyclic structure, acrylic monomer and butadiene to prepare the polyimide precursor with low water absorption rate. The polyimide with low water absorption rate is obtained by thermal imidization treatment, has low water absorption rate (which can be as low as 0.20%) and high heat resistance (Tg >300 ℃), and has good application prospect and large-scale popularization potential in the field of silicon carbide device packaging.

Inventors

  • HOU JUN
  • HE JIANFENG
  • TANG SHIWEN
  • LV JING

Assignees

  • 浙江奥首材料科技有限公司

Dates

Publication Date
20260505
Application Date
20251230

Claims (7)

  1. 1. The preparation method of the polyimide precursor with low water absorption rate is characterized by comprising the following steps of: adding alicyclic olefin monomer, acrylic ester monomer, butadiene and molecular weight regulator into organic solvent containing PAA chain segment, heating to 50-100 deg.C, adding initiator to initiate free radical polymerization, cooling after reaction to obtain low water absorption polyimide precursor; the mass ratio of the PAA chain segment to the alicyclic olefin monomer to the acrylic ester monomer to the butadiene to the molecular weight regulator is 40-90:2-10:6-12:2-12:0.1-0.6; The alicyclic olefin monomer is one or more of cyclopentadiene, dicyclopentadiene, norbornene, 1, 4-cyclohexanedimethanol divinyl ether and cyclohexyl methacrylate; the PAA chain segment is prepared by the following method: (1) Adding dianhydride and diamine into an organic solvent, then adding a blocking agent, and reacting for a period of time under the protection of nitrogen to generate a prepolymer; (2) Heating the prepolymer to 50-120 ℃ to react for a certain time to obtain product slurry; (3) Cooling the product slurry, precipitating, filtering and drying to obtain PAA chain segments; The end capping agent is one or more of 4-aminostyrene, 3-vinylaniline, 2-vinylaniline, 4-acetylene aniline, 3-acetylene aniline, 2-acetylene aniline, 3-alkynyl-2-fluoroaniline and 5-alkynyl-2-fluoroaniline.
  2. 2. The method for producing a low water absorption polyimide precursor according to claim 1, characterized in that, The addition amount of the initiator accounts for 0.5-5wt% of the total mass of the system; And/or, the mass ratio of the PAA chain segment to the organic solvent is 40-90:450-800; And/or the acrylic ester monomer is one or more of methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate, cyclohexyl acrylate, isobornyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, ethyl acrylate, isooctyl acrylate, lauryl acrylate and stearyl acrylate; and/or the molecular weight regulator is one or more of tertiary dodecyl mercaptan, n-dodecyl mercaptan, mercaptoethanol, thioglycollic acid, dodecyl trithiopropionate, alpha-methyl styrene dimer, alpha-ethyl styrene dimer, para-methyl-alpha-methyl styrene dimer, cumyl phenol and diphenylmethane; And/or the initiator is one or more of cumene hydroperoxide, potassium persulfate, azodiisobutyronitrile, tert-butyl peroxybenzoate, benzoyl peroxide, alpha-ethyl styrene dimer, p-methyl-alpha-methyl styrene dimer and alpha-methyl styrene dimer.
  3. 3. The method for preparing a low water absorption polyimide precursor according to claim 1, wherein the mass ratio of dianhydride, diamine, end capping agent and organic solvent is 2-20:5-15:0.1-5:60-90; And/or the dianhydride is pyromellitic dianhydride, 3',4,4' -biphenyltetracarboxylic dianhydride, 3', 4' -benzophenone tetracarboxylic dianhydride, 4 '-biphenyl ether dianhydride, hexafluorodianhydride, 3,4' -oxydiphthalic anhydride, diethylene glycol (4-trimethanhydride), bisphenol A-type dianhydride, 1,4,5, 8-naphthalene tetracarboxylic anhydride, 3', one or more of 4,4' -diphenyl sulfone tetracarboxylic dianhydride and 1,2,4, 5-cyclohexane tetracarboxylic dianhydride; And/or the diamine is one or more of 4,4' -diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 3' -diaminobenzophenone, 4' -diaminophenylsulfone, 2' -bis [4- (4-aminophenoxy) phenyl ] propane, 1, 3-bis (4-aminophenoxy) benzene, 4' -diaminodiphenyl methane, 2, 4-diaminotoluene, 4' -diaminobiphenyl, o-tolidine, hexamethylenediamine, butanediamine, pentanediamine, octanediamine, decanediamine, dodecanediamine, isophorone diamine, and 4,4' -diaminodicyclohexylmethane.
  4. 4. A low water absorption polyimide precursor prepared by the method of any one of claims 1-3.
  5. 5. A method for preparing polyimide with low water absorption is characterized by comprising the following steps of carrying out thermal imidization treatment on the polyimide precursor with low water absorption according to claim 4 to obtain polyimide with low water absorption.
  6. 6. A low water absorption polyimide prepared by the method of claim 5.
  7. 7. Use of the low water absorption polyimide of claim 6 in the field of silicon carbide device packaging.

Description

Polyimide precursor and polyimide with low water absorption rate, and preparation methods and applications thereof Technical Field The invention relates to a high molecular material technology, in particular to a polyimide precursor with low water absorption rate, polyimide and a preparation method and application thereof. Background Silicon carbide (SiC) power devices have become a new generation of power electronic core elements by virtue of wide forbidden bands, high thermal conductivity, high breakdown voltage and fast switching characteristics, and by realizing high-efficiency energy conversion in the fields of electric automobiles, photovoltaic inversion, rail transit and the like. However, the insulation protection layer material still faces a serious challenge in practical application. Although the traditional Polyimide (PI) has certain high temperature resistance (glass transition temperature Tg is more than or equal to 200 ℃), the water absorption rate is higher, the insulation resistance is reduced by 20% -30% after moisture absorption, and thermal oxidative decomposition is easy to occur in a long-term environment above 150 ℃, so that the dielectric property is deteriorated and the service life is shortened. Inorganic materials (such as silicon oxide and silicon nitride) or aluminum nitride (AlN) ceramics are resistant to high temperature, but have the problems of high brittleness, poor stress matching property, high processing cost, high interface defect control difficulty and the like. Aluminum nitride (AlN) ceramic has excellent thermal conductivity which can reach 170-200W/(m.K), but has high processing cost and high interface defect control difficulty, and restricts the large-scale application. Therefore, development of an insulating protective layer material with low water absorption, high thermal stability and good interface adhesion becomes a key technical direction for improving the reliability of the silicon carbide power device. At present, polyimide and a derivative composition thereof are the main stream development direction, but the prior art still has the problem of insufficient performance balance: In the international aspect, the eastern Japan reduces PI water absorption rate through fluorination modification, but causes dielectric loss to be increased (more than or equal to 0.008), and is not suitable for high-frequency scenes, and the Dupont in the United states adopts a PAA-boron nitride hybridization system to improve interface adhesion by 40%, but faces the problems of nanoparticle agglomeration, complex process, increased cost and the like. The nano silicon dioxide in-situ composite system developed by the national university of Qinghua reduces the water absorption, but is easy to generate interfacial peeling and insulating property attenuation when the nano silicon dioxide in-situ composite system is used for a long time at the temperature of more than 180 ℃. Especially in severe application scenes such as new energy automobiles (such as a battery pack in a 85 ℃/85% RH environment, a long-term working temperature of an electric drive system in 180-220 ℃ and a cold and hot cycle in a range of-40 ℃ to 150 ℃), the traditional or existing modified PI material has obvious defects of greatly reduced insulation resistance caused by high water absorption, limited high-temperature service life due to insufficient thermal decomposition temperature, interface microcracks caused by thermal expansion coefficient difference, and sudden drop of breakdown field intensity caused by high-temperature and high-humidity water tree effect. Even if the partial modification technology (such as fluorination modification and nano-composite) breaks through on a single index, the high reliability requirement cannot be met due to the problems of high dielectric loss, insufficient long-term thermal stability, process complexity and the like. Therefore, a polyimide material with multiple performances such as low water absorption and high heat resistance is needed to be synergistically optimized in the field so as to break through the technical bottleneck of silicon carbide power device packaging. Disclosure of Invention Aiming at the problem that the existing chain segment copolymer cannot have low water absorption and high heat resistance, the invention provides a low water absorption polyimide precursor, and polyimide prepared from the precursor has low water absorption (which can be as low as 0.20%) and high heat resistance (Tg >300 ℃), so that the polyimide has good application prospect and large-scale popularization potential in the field of silicon carbide device packaging. It should be noted that, in the present invention, unless otherwise specified, reference to the specific meaning of "comprising" as defined and described by the composition includes both the open meaning of "comprising", "including" and the like, and the closed meaning of "consisting of", "consisting of" and the like. In orde