Polyimide precursors, polyimides, and methods and applications thereof

Abstract

The application discloses a polyimide precursor, a polyimide and a preparation method and application thereof. The application further discloses a flexible diamine, and the structure is shown as formula (I). Wherein, the polyimide precursor is obtained by polycondensation or copolymerization of the diamine and aromatic tetracarboxylic dianhydride; the diamine comprises the flexible diamine. The polyimide is obtained by curing the polyimide precursor. The application further discloses a photosensitive resin, which comprises the polyimide precursor and a photosensitive monomer. The application takes the basic diamine with different side groups and flexible bridging groups as the reaction monomer of the polyimide precursor, increases the free volume and degree of freedom of the polymer chain, is more easy to directly polymerize or copolymerize with the anhydride, and significantly improves the imidization rate of the polyimide precursor under the condition of 200 DEG C. Meanwhile, the side groups with different free volumes and rigidity can adjust the interaction between the polymer molecular chains, so that higher thermal stability and good mechanical properties are realized, and the application requirements of the polyimide in the electronic packaging field are met.

Description

Technical Field

[0001] This invention relates to the field of electronic packaging technology, and in particular to a polyimide precursor, polyimide, its preparation method and application. Background Technology

[0002] Polyimide (PI) is widely used in semiconductor packaging due to its excellent electrical insulation, chemical resistance, mechanical properties, and thermal stability. Applications include α-particle shielding layers, stress buffer layers, interlayer dielectric materials, and photosensitive redistribution materials, playing an irreplaceable role in the modern microelectronics semiconductor industry. However, traditional polyimide resins require heating to 300-400℃ to achieve ideal performance, but some electronic components fail at temperatures exceeding 200-250℃. Furthermore, high-temperature processing often causes cracking, detachment, and recrystallization of low-melting-point solder joints in molded circuits, damaging the performance of the molded devices. In ultra-thin wafer devices, residual stress generated during high-temperature processing can lead to serious problems such as warping and peeling, affecting their reliability. Previous studies have shown that lowering the curing temperature can improve residual stress problems caused by thermal expansion coefficient mismatch due to the linear coefficient of thermal expansion (CTE). Therefore, developing polyimide materials with curing temperatures below 250℃, or even below 200℃, is particularly important.

[0003] There are currently three commonly used methods for preparing low-temperature curing polyimide resins. The first is the one-step method, which can realize the imidization process of polyamic acid at low temperature. Usually, a dehydrating agent and a catalyst are added to the polyamic acid solution. Common dehydrating agents are acetic anhydride, and catalysts are organic amines, including pyridine, quinoline, isoquinoline, β-picoline, etc. (ref: Macromolecules 31(17)(1998)5771–5778.). Since the widely used pyromellitic and biphenyl-type polyimides have extremely poor solubility in organic solvents (such as N-methylpyrrolidone or N,N-dimethylacetamide) and are difficult to process, this method is only suitable for soluble polyimide systems. Moreover, most of the commonly used high-boiling-point solvents contain carcinogens and cannot be widely used. Secondly, chemical curing agents are used to promote the dehydration and ring closure of polyamic acid at lower temperatures, completing the imidization process (Journal of Polymer Science Part a-Polymer Chemistry, 1996, 34, 651-658; Chemistry Letters, 2004, 33, 1156-1157; Journal of Photopolymer Science and Technology, 2017, 30, 139-146; J. Mater. Chem. C 8(42)(2020) 14886–14894.). Chemical curing agents mainly include carboxylic acid and tertiary amine alkaline catalysts, but the amount of curing agent used is generally 1-2 times the equivalent of the prepolymer, and the residue of the curing agent will have a serious impact on the mechanical properties of the film. Thirdly, novel diamine or anhydride monomers are prepared, and by introducing various chemical functional groups, the imidization process is made easier, thereby reducing the curing temperature. This method holds promise for addressing the scarcity of low-temperature curing polyimide resin materials, but very few novel monomers have been reported so far, making the development of novel diamine monomers crucial.

[0004] Chinese patent CN202011017412.8 discloses a polyimide precursor resin and its preparation method and application, which also includes a series of diamine monomers with low-temperature curing effect. However, the inventor pointed out in a subsequent paper (Polymer, 2021, 228(3):123963.) that the protected diamine monomer is too rigid, which restricts the movement of polymer molecular chains. Therefore, in the example, the imidization rate was only about 60-70% when cured at 200°C. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide polyimide precursors, polyimides, their preparation methods, and applications. This invention uses basic diamines with different side groups and flexible bridging groups as reactive monomers for polyimide precursors, increasing the free volume and degrees of freedom of the polymer chains, making direct polymerization or copolymerization with acid anhydrides easier, and significantly improving the imidization rate of the polyimide precursor at 200°C. Simultaneously, the different free volumes and rigidity of the side groups can adjust the interactions between polymer molecular chains, thereby achieving higher thermal stability and better mechanical properties, meeting the application requirements of polyimides in the field of electronic packaging.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention provides a flexible diamine, the structure of which is shown in formula (I):

[0008]

[0009] In formula (I), X1 and X2 are each independently selected from C or N atoms, and at least one of them is an N atom;

[0010] R1, R2, R3, and R4 are each independently selected from hydrogen or deuterium, methyl or deuterated methyl, substituted methyl, halogen, substituted or unsubstituted C2-C. 10 Straight-chain or branched alkyl groups, substituted or unsubstituted C6-C 30 Cycloalkyl, substituted or unsubstituted C5-C 30 Heterocyclic alkyl, C1-C 10 Alkoxy, C1-C 10 Alkylamino, substituted or unsubstituted C1-C 10 Silyl, substituted or unsubstituted C6-C 30 Aryl, C6~C 30 Aryloxy group, C6-C 30 Arylthioyl, C6-C 30 Arylsilyl, C6-C 30 arylamino, substituted or unsubstituted C6-C 30 heteroaryl, substituted or unsubstituted C6-C 30 Heteroaryl groups, substituted or unsubstituted C6-C 30 Heteroaryl thiols, substituted or unsubstituted C6-C 30 Heteroary aromatic silica-based, substituted or unsubstituted C6-C 30 Any one of heteroaromatic amino groups, monovalent nonaromatic fused polycyclic groups, monovalent nonaromatic fused heterocyclic groups, and acetyl groups;

[0011] L1 and L2 are each independently selected from -O-, -S-, -CH2-, -SiH2-, -CO-, -NH-, -CO-O-, -CO-NH-, sulfone groups, C2~C 12 Any of straight-chain and branched alkylene groups.

[0012] In the technical solution of the present invention, the aryl, aryloxy, arylthio, arylsilyl, arylamino, heteroaryl, heteroaryloxy, heteroarylthio, heteroarylsilyl, and heteroarylamino groups include polycyclic systems; the polycyclic system has two or more rings; the polycyclic system can be in which two adjacent rings share two or more carbons (i.e., fused rings), wherein at least one ring is aromatic, and the other rings can be cycloalkyl, heterocycloalkyl, cycloalkenyl, heterocycloalkenyl, and / or aryl; the polycyclic ring system can also be a biphenyl ring system that does not share carbon atoms, such as biphenylaryl or terphenyl.

[0013] In certain specific embodiments, the flexible diamines represented by formula (I) can be specifically listed as follows:

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022] In another aspect, the present invention provides a polyimide precursor obtained by polycondensation or copolymerization of a diamine and an aromatic tetracarboxylic acid dianhydride; the diamine includes the aforementioned flexible diamine.

[0023] In a preferred embodiment, in formula (I), X1 and X2 are N atoms; R1, R2, R3 and R4 are each independently selected from hydrogen or deuterium, methyl or deuterated methyl, trifluoromethyl, mercaptomethyl, halogen, ethyl, n-propyl, isopropyl, n-butyl, mercaptoethyl, methoxy, ethoxy, propoxy, trimethylsilyl or deuterated trimethylsilyl, phenyl, naphthyl, anthracene and acetyl; L1 and L2 are each independently selected from -O-, -S-, -CH2-, -SiH2-, -CO-, -NH- and sulfone groups.

[0024] In some specific embodiments, the diamine is selected from any one or more of the above-mentioned flexible diamines.

[0025] In some specific embodiments, the diamine further includes any one or more of the following diamines:

[0026]

[0027]

[0028]

[0029] In the technical solution of the present invention, the aromatic tetracarboxylic acid dianhydride has a structure as shown in formula (II):

[0030]

[0031] In formula (II), Ar3 is selected from any of the following structures:

[0032]

[0033] In another aspect, the present invention provides a method for preparing the above-mentioned polyimide precursor, comprising the following steps:

[0034] The diamine and aromatic tetracarboxylic acid dianhydride are directly subjected to a condensation reaction; or the diamine and aromatic tetracarboxylic acid dianhydride are subjected to a binary or ternary copolymerization.

[0035] Preferably, the temperature for the polycondensation reaction, binary or ternary copolymerization is 0–80°C;

[0036] Preferably, the polycondensation reaction, binary or ternary copolymerization time is 1 to 24 hours;

[0037] Preferably, the condensation reaction of binary or ternary copolymerization is carried out in a protective atmosphere;

[0038] In some specific embodiments, the polycondensation reaction, binary or ternary copolymerization is carried out in a solvent; the solvent is preferably N,N-dimethylacetamide or N-methylpyrrolidone.

[0039] In another aspect, the present invention provides a photosensitive resin comprising the above-mentioned polyimide precursor and photosensitive monomer.

[0040] In a preferred embodiment, the photosensitive monomer is selected from tetraethylene glycol trimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and 1,4-butanediol dimethacrylate. 1,6-hexanediol dimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, styrene, divinylbenzene, 4-vinyltoluene, 4-vinylpyridine, N-vinylpyrrolidone, hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 1,3-acryloyloxy-2-hydroxypropane, 1,3-methacryloyloxy-2-hydroxypropane, methylenebisacrylamide, N,N-dimethylacrylamide, and N-hydroxymethylacrylamide, or any one or more of these.

[0041] In another aspect, the present invention provides a polyimide obtained by curing the above-mentioned polyimide precursor.

[0042] In another aspect, the present invention provides the application of the above-mentioned flexible diamine, photosensitive resin or polyimide in the preparation of photoresists, semiconductor devices, display devices, lighting devices and in the field of electronic packaging.

[0043] The above technical solution has the following advantages or beneficial effects:

[0044] This invention uses basic diamines with different side groups and flexible bridging groups as reactive monomers for polyimide precursors. Containing basic asymmetric nitrogen-containing aromatic rings, these monomers can undergo autocatalytic reactions in the heat-cured polyimide precursors, accelerating the imidization process. Simultaneously, the introduction of side groups and flexible bridging groups with varying free volumes and rigidities allows for the adjustment of interactions between polymer molecular chains, comprehensively regulating the thermal stability and mechanical properties of the polyimide film. This diamine monomer can improve the imidization rate of polyimide precursor resins at temperatures below 250°C, and even below 200°C, achieving low-temperature curing of the polyimide precursor while maintaining good thermal stability and mechanical properties, thus meeting the application requirements of microelectronic chip materials, packaging materials, and interlayer dielectric layers. Attached Figure Description

[0045] Figure 1 These are ATR-FTIR spectra comparisons of the polyimide precursors in Examples 1, 3, 5, and 9 cured at different temperatures.

[0046] Figure 2These are comparison diagrams of the fracture stress of polyimide in Examples 2, 4, 6, 7, and the comparative example. Detailed Implementation

[0047] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0048] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0049] Manufacturing Example 1:

[0050] 4,4'-((6-methylpyrimidin-2,4-diyl)bis(oxy))diphenylamine, the structure of which is shown below:

[0051]

[0052] The specific synthesis process is as follows:

[0053]

[0054] (1) First, 2,4-dichloro-6-methylpyrimidine (1 eq.), p-nitrophenol (2.5 eq.), and potassium carbonate (2.5 eq.) were added sequentially to a three-necked round-bottom flask. Nitrogen gas was introduced, and under nitrogen protection, ultra-dry N,N-dimethylformamide solvent was added. The reaction was carried out at 150°C for 12 hours. After cooling to room temperature, the reactants were extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain a light yellow intermediate 1 with a yield of 85%. NMR data: 1 H NMR (400MHz, DMSO-d6), δ8.44-8.08(m,4H),7.67-7.35(m,4H),6.97(s,1H),2.41(s,3H);

[0055] (2) Weigh intermediate 1 (1 eq.) and palladium / carbon 10% (0.1 eq.) sequentially into a three-necked round-bottom flask, add ultra-dry tetrahydrofuran, heat to reflux under a nitrogen atmosphere, add hydrazine hydrate 85% (5 eq.) dropwise, reflux for 12 hours, cool to room temperature, filter out the palladium-carbon catalyst, evaporate the organic phase to dryness, purify by column chromatography, and obtain a white product with a yield of 78%. NMR data: 1HNMR (400MHz, DMSO-d6), δ6.90-6.72 (m, 4H), 6.57 (dd, J = 16.8, 8.8Hz, 4H), 6.34 (s, 1H), 5.11 (s, 2H), 4.98 (s, 2H), 2.25 (s, 3H).

[0056] Manufacturing Example 2:

[0057] 4,4'-((5-methylpyrimidin-2,4-diyl)bis(oxy))diphenylamine, the structure of which is shown below:

[0058]

[0059] The specific synthesis process is as follows:

[0060]

[0061] (1) First, 2,4-dichloro-5-methylpyrimidine (1 eq.), p-nitrophenol (2.5 eq.), and potassium carbonate (2.5 eq.) were added sequentially to a three-necked round-bottom flask. Nitrogen gas was introduced, and under nitrogen protection, ultra-dry N,N-dimethylformamide solvent was added. The reaction was carried out at 150°C for 1 hour. After cooling to room temperature, the reactants were extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain a light yellow intermediate 1 with a yield of 88%. NMR data: 1 H NMR (400MHz, DMSO-d6), δ8.46(s,1H),8.27(dd,J=25.4,9.1Hz,4H),7.53(d,J=9.1Hz,2H),7.42(d,J=9.2Hz,2H),2.27(s,3H);

[0062] (2) Weigh intermediate 1 (1 eq.) and palladium / carbon 10% (0.1 eq.) and add them sequentially to a three-necked round-bottom flask. Add ultra-dry tetrahydrofuran, heat to reflux under a nitrogen atmosphere, add hydrazine hydrate 85% (5 eq.) dropwise, reflux for 16 hours, cool to room temperature, filter out the palladium / carbon catalyst, evaporate the organic phase to dryness, and purify by column chromatography to obtain a white product with a yield of 75%. NMR data: 1 HNMR(400MHz, DMSO-d6), δ8.14(d,J=0.8Hz,1H),6.85(d,J=8.8Hz,2H),6.75(d,J =8.8Hz,2H),6.55(dd,J=24.9,8.8Hz,4H),5.05(s,2H),4.98(s,2H),2.15(s,3H).

[0063] Manufacturing Example 3:

[0064] 4,4'-((5-(trifluoromethyl)pyrimidin-2,4-diyl)bis(oxy))diphenylamine, the structure of which is shown below:

[0065]

[0066] The specific synthesis process is as follows:

[0067]

[0068] (1) First, 2,4-dichloro-5-(trifluoromethyl)pyrimidine (1 eq.), p-nitrophenol (2.5 eq.), and potassium carbonate (2.5 eq.) were added sequentially to a three-necked round-bottom flask. Nitrogen gas was introduced, and ultra-dry N,N-dimethylformamide solvent was added under nitrogen protection. The reaction was carried out at 150°C for 1 hour. After cooling to room temperature, the reactants were extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain a light yellow intermediate 1 with a yield of 88%. NMR data: 1 H NMR (500MHz, CDCl3), δ8.35–8.26(m,2H),8.18–8.11(m,2H),8.08(s,1H),7.54–7.43(m,2H),7.08–6.96(m,2H);

[0069] (2) Weigh intermediate 1 (1 eq.) and palladium / carbon 10% (0.1 eq.) and add them sequentially to a three-necked round-bottom flask. Add ultra-dry tetrahydrofuran, heat to reflux under a nitrogen atmosphere, add hydrazine hydrate 85% (5 eq.) dropwise, reflux for 12 hours, cool to room temperature, filter out the palladium / carbon catalyst, evaporate the organic phase to dryness, and purify by column chromatography to obtain a white product with a yield of 80%. NMR data: δ 1 HNMR (500MHz, CDCl3), 8.08 (s, 1H), 6.60-6.55 (m, 8H), 5.5 (s, 4H).

[0070] Manufacturing Example 4:

[0071] 4,4'-((5,6-dimethoxypyrimidine-2,4-diyl)bis(oxy))diphenylamine, with the structure shown below:

[0072]

[0073] The specific synthesis process is as follows:

[0074]

[0075] (1) First, 2,4-dichloro-5,6-dimethoxypyrimidine (1 eq.), p-nitrophenol (2.5 eq.), and potassium carbonate (2.5 eq.) were added sequentially to a three-necked round-bottom flask. Nitrogen gas was introduced, and ultra-dry N,N-dimethylformamide solvent was added under nitrogen protection. The reaction was carried out at 150°C for 1 hour. After cooling to room temperature, the reactants were extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain a light yellow intermediate 1 with a yield of 88%. NMR data: 1 H NMR (500MHz, CDCl3) δ8.38–8.24(m,2H),8.21–8.07(m,2H),7.55–7.42(m,2H),7.10–6.92(m,2H),4.06(s,3H),3.92(s,3H);

[0076] (2) Weigh intermediate 1 (1 eq.) and palladium / carbon 10% (0.1 eq.) sequentially into a three-necked round-bottom flask, add ultra-dry tetrahydrofuran, heat to reflux under a nitrogen atmosphere, add hydrazine hydrate 85% (5 eq.) dropwise, reflux for 12 hours, cool to room temperature, filter out the palladium-carbon catalyst, evaporate the organic phase to dryness, purify by column chromatography, and obtain a white product with a yield of 80%. NMR data: δ 1 HNMR(500MHz, CDCl3),8.40-8.32(m,8H),5.29(s,4H),4.06(s,3H),3.83(s,3H).

[0077] Manufacturing Example 5:

[0078] 4,4'-((6-(anthracite-2-yl)pyrimidin-2,4-diyl)bis(oxy))diphenylamine, with the structure shown below:

[0079]

[0080] The specific synthesis process is as follows:

[0081]

[0082] (1) First, 4-bromo-2,6-dichloropyrimidine (1 eq.), anthracene 2-boronic acid (1.05 eq.), potassium carbonate (2.5 eq.), and Pd(PPh3)4 (0.01 eq.) were sequentially added to a three-necked round-bottom flask. Nitrogen gas was introduced, and toluene, ethanol, and water (volume ratio 2:1:1) were added under nitrogen protection. The mixture was refluxed and stirred for 12 hours. After cooling to room temperature, the reactants were extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain a light white intermediate 1 with a yield of 91%. NMR data: 1HNMR(500MHz, CDCl3), δ8.87(t,J=3.0Hz,1H),8.45(dt,J=14.9,2.9Hz,2H),8.33(dd,J=15.0,2.9Hz,1H),8 .01(ddd,J=11.0,7.0,3.0Hz,2H),7.91(dd,J=15.0,3.1Hz,1H),7.54(dd,J=11.1,6.9Hz,2H),7.13(s,1H);

[0083] (2) Intermediate 1 (1 eq.), p-nitrophenol (2.5 eq.), and potassium carbonate (2.5 eq.) were sequentially added to a three-necked round-bottom flask. Nitrogen gas was introduced, and ultra-dry N,N-dimethylformamide solvent was added under nitrogen protection. The reaction was carried out at 150°C for 1 hour. After cooling to room temperature, the reaction mixture was extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain the light yellow intermediate 2, with a yield of 68%. NMR data: 1 H NMR(500MHz, CDCl3), δ8.87(t,J=3.0Hz,1H),8.45(dt,J=14.9,2.9Hz,2H),8.37–8.26(m,3H),8.20–8.1 0(m,2H),8.01(s,2H),7.91(dd,J=15.0,3.1Hz,1H),7.63–7.38(m,4H),7.08–6.97(m,2H),6.56(s,1H);

[0084] (3) Weigh intermediate 2 (1 eq.) and palladium / carbon 10% (0.1 eq.) and add them sequentially to a three-necked round-bottom flask. Add ultra-dry tetrahydrofuran, heat to reflux under a nitrogen atmosphere, add hydrazine hydrate 85% (5 eq.) dropwise, reflux for 12 hours, cool to room temperature, filter out the palladium / carbon catalyst, evaporate the organic phase to dryness, and purify by column chromatography to obtain a white product with a yield of 67%. NMR data: 1 HNMR(500MHz, CDCl3), δ8.87(t,J=3.0Hz,1H),8.45(dt,J=14.9,2.9Hz,2H),8.33(dd,J=15.0,2.9Hz,1H),8.01(ddd,J=11.0,7 .0,3.0Hz,2H),7.91(dd,J=15.0,3.1Hz,1H),7.54(dd,J=11.1,6.9Hz,2H),6.96(s,2H),6.56(s,1H),6.50(s,8H),5.12(s,2H).

[0085] Manufacturing Example 6:

[0086] 4,4'-((5-(4-(triphenylsilyl)phenyl)pyrimidin-2,4-diyl)bis(oxy))diphenylamine, with the structure shown below:

[0087]

[0088] The specific synthesis process is as follows:

[0089]

[0090] (1) First, 5-bromo-2,4-dichloropyrimidine (1 eq.), 4-(triphenylsilyl)phenyl)boronic acid (1.05 eq.), potassium carbonate (2.5 eq.), and Pd(PPh3)4 (0.01 eq.) were sequentially added to a three-necked round-bottom flask. Nitrogen gas was introduced, and toluene, ethanol, and water (volume ratio 2:1:1) were added under nitrogen protection. The mixture was refluxed and stirred for 12 hours. After cooling to room temperature, the reactants were extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain a light white intermediate 1 with a yield of 86%. NMR data: 1 H NMR (500MHz, CDCl3), δ9.40 (s, 1H), 7.87 (d, J = 13.2Hz, 2H), 7.65 (d, J = 14.3Hz, 2H), 7.46-7.38 (m, 15H);

[0091] (2) Intermediate 1 (1 eq.), p-nitrophenol (2.5 eq.), and potassium carbonate (2.5 eq.) were sequentially added to a three-necked round-bottom flask. Nitrogen gas was introduced, and ultra-dry N,N-dimethylformamide solvent was added under nitrogen protection. The mixture was reacted at 150°C for 1 hour, cooled to room temperature, and the reaction mixture was extracted to the organic phase with 500 mL of water and 300 mL of dichloromethane. The organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed to obtain the light yellow intermediate 2, with a yield of 61%. NMR data: 1 H NMR(500MHz, CDCl3), δ8.52(s,1H),8.30(m,2H),8.14(m,2H),7.87(m,2H),7.65(d ,J=13.2Hz,2H),7.48(d,J=3.4Hz,2H),7.46–7.38(m,15H),7.02(d,J=8.6Hz,2H);

[0092] (3) Weigh intermediate 2 (1 eq.) and palladium / carbon 10% (0.1 eq.) and add them sequentially to a three-necked round-bottom flask. Add ultra-dry tetrahydrofuran, heat to reflux under a nitrogen atmosphere, add hydrazine hydrate 85% (5 eq.) dropwise, reflux for 12 hours, cool to room temperature, filter out the palladium / carbon catalyst, evaporate the organic phase to dryness, and purify by column chromatography to obtain a white product with a yield of 62%. NMR data:1 HNMR(500MHz, CDCl3), δ8.96(s,1H),8.67(m,2H),8.42(m,2H),8.21-8.09(m,15H),7.60-7.55(m,8H),5.03(s,4H).

[0093] Example

[0094] The polyimide in the following examples is prepared by the following method:

[0095] (1) Pre-treat dianhydride and diamine to remove moisture and impurities; then, at low temperature or room temperature, pour an appropriate amount of one or more diamines into a flask, add a polar organic solvent and mix well, then purge with nitrogen to keep the system under a nitrogen atmosphere, and then add dianhydride in batches (the molar ratio of diamine to dianhydride is 0.9 to 1), adding at intervals of 10 to 30 minutes, and stirring continuously for 5 to 24 hours to obtain a polyamic acid (PAA) solution, i.e., polyimide precursor;

[0096] (2) Spread the polyamic acid solution evenly on a flat plate by spin coating or scraping, and bake it on a hot plate for a few minutes to remove some of the organic solvent.

[0097] (3) Finally, thermal imidization is carried out under nitrogen or air atmosphere, mainly by step heating, and then cooled to room temperature to obtain polyimide resin.

[0098] Example 1

[0099] (1) First, the dianhydride and diamine were pretreated to remove moisture and impurities. The diamine was treated in a vacuum oven at 60°C for 3 hours, and the dianhydride was treated in a vacuum oven at 160°C for 4 hours. Then, at room temperature, 10 mmol of 4,4'-((6-methylpyrimidin-2,4-diyl)bis(oxy))diphenylamine was dissolved in an ultra-dry N,N-dimethylacetamide (DMAc) solution in a flask. Then, under a nitrogen atmosphere and ice bath conditions, 10 mmol of pyromellitic dianhydride (PMDA) was added in two portions and stirred for 24 hours to obtain PAA-1 solution.

[0100] (2) Then, the polyamic acid solution is evenly spread on the smooth copper surface by spin coating at a speed of 1000 rpm for 30 seconds. It is then soft-baked on a hot plate at 80°C for 10 minutes to remove some of the organic solvent.

[0101] (3) Finally, thermal imidization is carried out under a nitrogen atmosphere, mainly by stepwise heating:

[0102] The heating program is as follows: heat to 100℃ at a heating rate of 5℃ / minute and hold for 1 hour (100℃ / 1 hour); then heat to 200℃ at a heating rate of 5℃ / minute and hold for 3 hours (200℃ / 3 hours); then cool to room temperature to obtain low-temperature cured polyimide PI-11.

[0103] The heating program is 5℃ / minute, 100℃ / 1 hour, 200℃ / 1 hour, 250℃ / 2 hours, and then cooled to room temperature to obtain low-temperature cured polyimide PI-12;

[0104] The heating program was changed to 5℃ / minute, 100℃ / hour, 200℃ / hour, 300℃ / hour, 350℃ / hour, with a heating rate of 5℃ / minute. Then it was cooled to room temperature to obtain low-temperature cured polyimide PI-13.

[0105] Example 2

[0106] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with a mixed diamine of 4,4'-((6-methylpyrimidin-2,4-diyl)bis(oxy))diphenylamine and 4,4'-diaminodiphenyl ether (ODA) in a molar ratio of 1 mmol:9 mmol, and PAA-2 is obtained by polymerization; then, polyimides PI-21, PI-22 and PI-23 are obtained by step temperature curing.

[0107] Example 3

[0108] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with a mixed diamine of 4,4'-((6-methylpyrimidin-2,4-diyl)bis(oxy))diphenylamine and 4,4'-diaminodiphenyl ether (ODA) in a molar ratio of 2 mmol:8 mmol, and PAA-3 is obtained by polymerization; then, polyimides PI-31, PI-31, and PI-33 are obtained by step temperature curing.

[0109] Example 4

[0110] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with a mixed diamine of 4,4'-((6-methylpyrimidin-2,4-diyl)bis(oxy))diphenylamine and 4,4'-diaminodiphenyl ether (ODA) in a molar ratio of 3 mmol:7 mmol, and PAA-4 is obtained by polymerization; then polyimides PI-41, PI-42 and PI-43 are obtained by step temperature curing.

[0111] Example 5

[0112] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with 4,4'-((5-methylpyrimidin-2,4-diyl)bis(oxy))diphenylamine, which is polymerized with pyromellitic dianhydride (PMDA) to obtain PAA-5; then polyimides PI-51, PI-52 and PI-53 are obtained by alternating heating and curing.

[0113] Example 6

[0114] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with 4,4'-((5-(trifluoromethyl)pyrimidin-2,4-diyl)bis(oxy))diphenylamine, which is polymerized with pyromellitic dianhydride (PMDA) to obtain PAA-6, and then polyimides PI-61, PI-62 and PI-63 are obtained by step temperature increase curing.

[0115] Example 7

[0116] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with 4,4'-((5,6-dimethoxypyrimidine-2,4-diyl)bis(oxy))diphenylamine, which is polymerized with pyromellitic dianhydride (PMDA) to obtain PAA-7; then, polyimides PI-71, PI-72, and PI-73 are obtained by step-by-step temperature curing.

[0117] Example 8

[0118] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with 4,4'-((6-(anthracene-2-yl)pyrimidin-2,4-diyl)bis(oxy))diphenylamine, which is polymerized with pyromellitic dianhydride (PMDA) to obtain PAA-8; then, polyimides PI-81, PI-82, and PI-83 are obtained by step-by-step temperature curing.

[0119] Example 9

[0120] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with 4,4'-((5-(4-(triphenylsilyl)phenyl)pyrimidin-2,4-diyl)bis(oxy))diphenylamine, which is polymerized with pyromellitic dianhydride (PMDA) to obtain PAA-9; then, polyimides PI-91, PI-92, and PI-93 are obtained by step-by-step temperature curing.

[0121] Example 10

[0122] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with 3,3,4,4-diphenylsulfone tetracarboxylic acid dianhydride (DSDA), and PAA-10 is obtained by direct polymerization; then, polyimides PI-101, PI-102, and PI-103 are obtained by step-by-step temperature curing.

[0123] Example 11

[0124] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and PAA-11 is obtained by direct polymerization. Then, polyimides PI-111, PI-112, and PI-113 are obtained by step temperature curing.

[0125] Example 12

[0126] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), and PAA-12 is obtained by direct polymerization. Then, polyimides PI-121, PI-122, and PI-123 are obtained by step-by-step temperature curing.

[0127] Example 13

[0128] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with 4,4'-oxybisphthalic anhydride (ODPA), and PAA-13 is obtained by direct polymerization. Then, polyimides PI-131, PI-132 and PI-133 are obtained by step temperature curing.

[0129] Example 14

[0130] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with bisphenol A type diether dianhydride (BPADA), and PAA-14 is obtained by direct polymerization. Then, polyimides PI-141, PI-142 and PI-143 are obtained by step temperature curing.

[0131] Example 15

[0132] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with hexafluorodianhydride (6FDA), and PAA-15 is obtained by direct polymerization. Then, polyimides PI-151, PI-152 and PI-153 are obtained by step temperature curing.

[0133] Example 16

[0134] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with a mixed dianhydride of hexafluorodianhydride (6FDA) and PMDA, with a mixing molar ratio of 1 mmol: 9 mmol. PAA-16 is obtained by direct polymerization, and then polyimides PI-161, PI-162 and PI-163 are obtained by step temperature curing.

[0135] Example 17

[0136] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with a mixed dianhydride of hexafluorodianhydride (6FDA) and PMDA, with a mixing molar ratio of 2 mmol: 8 mmol. PAA-17 is obtained by direct polymerization and then polyimides PI-171, PI-172 and PI-173 are obtained by step temperature curing.

[0137] Example 18

[0138] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with a mixed dianhydride of hexafluorodianhydride (6FDA) and PMDA, with a mixing molar ratio of 3 mmol:7 mmol. PAA-18 is obtained by direct polymerization, and then polyimides PI-181, PI-182 and PI-183 are obtained by step temperature curing.

[0139] Example 19

[0140] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with a mixture of hexafluorodianhydride (6FDA), DSDA and PMDA in a molar ratio of 1 mmol: 1 mmol: 8 mmol. PAA-19 is obtained by direct polymerization and then polyimides PI-191, PI-192 and PI-193 are obtained by step temperature curing.

[0141] Example 20

[0142] The difference between the preparation method of this embodiment and that of Example 1 is that the dianhydride in step (1) is replaced with a mixture of hexafluorodianhydride (6FDA), DSDA and PMDA in a molar ratio of 2 mmol: 1 mmol: 7 mmol. PAA-20 is obtained by direct polymerization and then polyimides PI-201, PI-202 and PI-203 are obtained by step temperature curing.

[0143] Example 21

[0144] In this embodiment, 350g of polyimide precursor PAA-2 (solid content 15%) prepared in Example 2 was diluted with 200mL of N,N-dimethylacetamide, and then 7.5mL of trifluoroacetic anhydride was slowly added under a nitrogen atmosphere, and the temperature was raised to 50℃ and reacted for 2h; then 15g of hydroxyethyl methacrylate was added and stirred overnight at 50℃; the resulting product was precipitated in methanol, filtered and dried to obtain a grayish-yellow solid, i.e., the photosensitive resin.

[0145] The photoresist was prepared using the above-mentioned photosensitive resin, and the specific formula is as follows: 1.0 parts by weight of photosensitive resin, 0.03 parts by weight of tetraethylmielone, 0.06 parts by weight of o-chlorohexaaryldiimidazole, 0.02 parts by weight of 2-mercaptobenzoxazole, and 30 parts by weight of N-methylpyrrolidone.

[0146] Photolithographic performance testing of photoresist: Under ultraviolet light exposure (EVG610), the exposure dose was 370 mJ / cm². 2 The development time was 20 seconds (using developer KS5400), resulting in a pattern with a linewidth / spacing of 15 μm. The pattern was then examined using a scanning electron microscope (SEM, NanoSEM 450).

[0147] Comparative Example 1

[0148] The difference between the preparation method of this embodiment and that of Example 1 is that the diamine in step (1) is replaced with 4,4'-diaminodiphenyl ether, which is polymerized with pyromellitic dianhydride (PMDA) to obtain PAA-0, and then polyimides PI-01, PI-02 and PI-03 are obtained by step temperature curing.

[0149] Effect Example

[0150] 1. The degree of imidization of the polyimides prepared in the above embodiments and comparative examples was tested. The test method was as follows: the ratio of the peak area of ​​the CN stretching vibration peak of the polyimide ring to the CC stretching vibration peak of the benzene ring in the infrared spectrum was compared. The ratio obtained at 350℃ was used as a reference. The calculation formula is as follows:

[0151] Imidization Degree(ID) = (S C-N / S C-C ) T / (S C-N / S C-C ) 350 ;

[0152] Among them, S C-N S represents the peak area of ​​CN stretching vibration. C-C The peak area of ​​the CC stretching vibration.

[0153] The results of the imidization degree test of the polyimides in Examples 1-9 and the comparative examples are shown in Table 1:

[0154] Table 1

[0155] Example 1 PAA-1 97％ 98％ Example 2 PAA-2 94％ 97％ Example 3 PAA-3 94％ 96％ Example 4 PAA-4 98％ 99％ Example 5 PAA-5 95％ 98％ Example 6 PAA-6 93％ 98％ Example 7 PAA-7 94％ 97％ Example 8 PAA-8 93％ 99％ Example 9 PAA-9 94％ 98％ Comparative Example 1 PAA-01 82％ 86％

[0156] Figure 1 The images show a comparison of the ATR-FTIR spectra of the polyimide precursors PAA-1, PAA-3, PAA-5, and PAA-9 prepared in Examples 1, 3, 5, and 9 after curing at different temperatures. The results show that, compared to the polyimide precursor prepared in Comparative Example 1, the polyimide precursors PAA-1 to PAA-9 obtained by copolymerization or direct polymerization of the diamine monomers in Examples 1-9 all achieved imidization rates of over 90% at 200°C and 250°C.

[0157] 2. The mechanical and thermodynamic properties of the polyimides prepared in the above embodiments and comparative examples were tested. The test results are shown in Table 2:

[0158] Table 2

[0159]

[0160] The mechanical properties were tested using a dynamic mechanical thermal analyzer (TA, DMAQ800). The cured polyimide film obtained in the examples was cut into 3mm × 5mm strips for testing. The resulting fracture stress comparison diagram is shown below. Figure 2 As shown. From Figure 2 As can be seen, the mechanical properties of the polyimide films in Examples 2, 4, 6, and 7 are significantly improved compared to those in Comparative Example 1, especially in Example 2. Specifically, the polyimide film formed by curing the polyimide precursor prepared in Example 2 at 200°C has an elongation at break of 61%, a breaking stress of 138 MPa, and a Young's modulus of 3.03 GPa. In contrast, the polyimide film formed by curing at 200°C in Comparative Example 1 has an elongation at break of 50%, a breaking stress of 124 MPa, and a Young's modulus of 2.75 GPa. Therefore, the polyimide film formed by curing the polyimide precursor obtained using a pyrimidine-containing flexible diamine monomer at low temperature has superior mechanical properties compared to the polyimide film obtained by curing ordinary polyimide precursor resin without nitrogen at low temperature.

[0161] As can be seen from the performance data comparison in Table 2, the polyimide film formed by curing the polyimide precursor resin provided by this invention at 200℃ exhibits improved thermal and mechanical properties compared to polyimide films obtained by polymerization of diamine ODA and dianhydride PMDA. This indicates that the combination of the large-volume side groups and the basicity of the pyrimidine ring in the diamine not only increases the imidization rate during low-temperature curing but also ensures good thermal and mechanical stability of the film.

[0162] The applicant declares that this invention illustrates a polyimide precursor resin, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above process steps, meaning that this invention does not necessarily rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A polyimide precursor, characterized in that, The polyimide precursor is obtained by polycondensation or copolymerization of a diamine and an aromatic tetracarboxylic acid dianhydride; the diamine includes a flexible diamine; the structure of the flexible diamine is shown in formula (I): （I） In formula (I), X1 and X2 are N atoms; R1 is selected from hydrogen or deuterium, methyl or deuterated methyl, trifluoromethyl, C1~C1. 10 alkoxy and R2 is selected from hydrogen or deuterium, methyl or deuterated methyl, C1~C1. 10 Alkoxy, C6~C 30 Any of the aryl groups; and, R1 is selected from hydrogen or deuterium and R2 is selected from hydrogen or deuterium, but this does not hold simultaneously; R3 and R4 are hydrogen or deuterium; L1 and L2 are -O-.

2. The polyimide precursor according to claim 1, characterized in that, In formula (I), R1 is hydrogen or deuterium, methyl or deuterated methyl, trifluoromethyl, methoxy, R2 is any one of hydrogen or deuterium, methyl or deuterated methyl, methoxy, or anthracene.

3. The polyimide precursor according to claim 1, characterized in that, The diamine is any one or more of the flexible diamines; the structure of the flexible diamine is shown in formula (I): （I） In formula (I), X1 and X2 are N atoms; R1 is selected from hydrogen or deuterium, methyl or deuterated methyl, trifluoromethyl, C1~C1. 10 alkoxy and R2 is selected from hydrogen or deuterium, methyl or deuterated methyl, C1~C1. 10 Alkoxy, C6~C 30 Any of the aryl groups; and, R1 is selected from hydrogen or deuterium and R2 is selected from hydrogen or deuterium, but this does not hold simultaneously; R3 and R4 are hydrogen or deuterium; L1 and L2 are -O-.

4. The polyimide precursor according to claim 1, characterized in that, The diamine further includes any one or more of the following diamines:

5. The polyimide precursor according to claim 1, characterized in that, The aromatic tetracarboxylic acid dianhydride has the structure shown in formula (II): (II) In formula (II), Ar3 is selected from any of the following structures:

6. The method for preparing the polyimide precursor according to any one of claims 1-5, characterized in that, The process includes the following steps: directly subjecting the diamine and aromatic tetracarboxylic dianhydride to a condensation reaction; or subjecting the diamine monomer and aromatic tetracarboxylic dianhydride to a binary or ternary copolymerization.

7. The preparation method according to claim 6, characterized in that, The temperature for the condensation reaction, binary or ternary copolymerization is 0~80℃.

8. The preparation method according to claim 6, characterized in that, The time for the condensation reaction, binary or ternary copolymerization is 1 to 24 hours.

9. The preparation method according to claim 6, characterized in that, The condensation reaction, binary or ternary copolymerization is carried out in a protective atmosphere.

10. A photosensitive resin, characterized in that, The photosensitive resin comprises the polyimide precursor and photosensitive monomer as described in any one of claims 1-5.

11. The photosensitive resin according to claim 10, characterized in that, The photosensitive monomer is selected from tetraethylene glycol trimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, pentaerythritol trienoic acid ester, pentaerythritol tetraacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, styrene, divinylbenzene, 4-vinyltoluene, and 4-vinylpyridine. N -Vinylpyrrolidone, Hydroxyethyl methacrylate, 2-Hydroxyethyl acrylate, 1,3-Acryloyloxy-2-hydroxypropane, 1,3-Methacryloxy-2-hydroxypropane, Methylenebisacrylamide, N,N -Dimethacrylamide and N Any one or more of hydroxymethylacrylamide.

12. A polyimide, characterized in that, The polyimide is obtained by curing the polyimide precursor according to any one of claims 1-5.

13. The application of the polyimide precursor of any one of claims 1-5, the photosensitive resin of claim 10, or the polyimide of claim 12 in the preparation of photoresists, semiconductor devices, display devices, lighting devices, and electronic packaging.

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