Polyimide precursor and preparation method thereof, polyimide precursor glue solution and preparation method thereof, and polyimide film

Abstract

The invention relates to the technical field of materials, in particular to a polyimide precursor and a preparation method thereof, a polyimide precursor glue solution and a preparation method thereof, and a polyimide film. The main chain of the polyimide precursor contains a keto-carbonyl self-sensitizing group and a group containing abstractable reactive hydrogen, and the keto-carbonyl self-sensitizing group and the group can realize photo-crosslinking. Meanwhile, the polyimide precursor also has an ester-type photosensitive branched chain, and a cross-linked structure is easily formed under the action of a photo-crosslinking agent and the like, so that dual sensitization is realized. The polyimide film prepared from the polyimide precursor not only retains the high resolution of ester type photosensitive polyimide, but also reduces the proportion of photosensitive branched chains in the structure, so that the film shrinkage effect after curing is reduced, and the prepared polyimide film has both high resolution and lower film thickness shrinkage rate.

Description

Technical Field

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

[0002] Polyimide (PI) is widely used in chip manufacturing and device packaging due to its low dielectric constant, high thermal stability, and chemical resistance. Non-photosensitive polyimide requires the use of traditional photoresists to achieve patterning on PI. However, the introduction of photoresists complicates the patterning process, increases the difficulty, and photoresist stripping and subsequent etching processes can easily cause irreversible damage to the chip substrate. Against this backdrop, photosensitive polyimide (PSPI), due to its inherent photosensitivity, allows for direct pattern transfer, greatly simplifying chip manufacturing processes and thus attracting widespread attention in chip manufacturing and packaging.

[0003] Photosensitive polyimides are classified into two categories: positive photosensitive polyimides and negative photosensitive polyimides. Negative photosensitive polyimides are further divided into three types: ester-type photosensitive polyimides, salt-type photosensitive polyimides, and self-sensitizing photosensitive polyimides. Self-sensitizing photosensitive polyimides achieve photosensitivity without the need for additional photosensitizers or photoinitiators. However, because their photosensitive groups are distributed on the molecular backbone and are relatively small, most are unable to crosslink due to steric hindrance, resulting in poor photosensitivity. In contrast, ester-type photosensitive polyimides have photosensitive groups distributed on the molecular side chains, which, with the support of photocrosslinking agents, are more likely to form crosslinked structures. Therefore, ester-type photosensitive polyimides have higher photosensitivity. However, these photosensitive branched structures and additives such as photocrosslinkers are removed during the curing process after exposure and development, resulting in a significant shrinkage of the cured film thickness. This defect also limits the application of ester-type photosensitive polyimide.

[0004] Existing technologies introduce photosensitive groups into the molecular chain to impart photosensitivity, then use 4-hydroxyphthalic anhydride as a capping agent to introduce phenolic hydroxyl groups at the ends of the main chain. After imidization, unsaturated acid anhydrides are introduced, reacting with the phenolic hydroxyl groups at the ends of the main chain to produce carboxyl groups, forming an alkali-soluble negatively photosensitive polyimide. This product has high photosensitivity, but its molecular structure is complex, the operation is cumbersome, and the chemical imidization process results in a low resin molecular weight, making it difficult to form thick films. Another approach involves introducing triamine and trihydride monomers, designing self-sensitizing groups at the outer ends of hyperbranched macromolecular chains in a three-dimensional spherical structure. This solves the problem of poor photosensitivity in self-sensitized photosensitive polyimides. However, the synthesis of hyperbranched polyimides is difficult, and the molecular weight is hard to control stably, thus limiting its large-scale application. Furthermore, by mixing a diamine with a ketone carbonyl group and another diamine monomer containing an active hydrogen that can be abstracted, and then polymerizing it with a dianhydride, the self-sensitizing groups are distributed on the side chains, thereby enhancing the photosensitivity of the self-sensitizing polyimide. However, due to the presence of aromatic ring structures on the side chains, the resin molecules are relatively rigid, and the film is brittle after formation, which limits its application in chip manufacturing and packaging.

[0005] Therefore, there is an urgent need to provide a photosensitive polyimide that balances strong photosensitivity with low film shrinkage. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention provides a polyimide precursor and its preparation method, a polyimide precursor solution and its preparation method, and a polyimide film. The polyimide film obtained from this polyimide precursor can achieve both high resolution and low film thickness shrinkage.

[0007] Therefore, a first aspect of the present invention provides a polyimide precursor having the structure shown in formula (I):

[0008]

[0009] Where, m:n = (3:7) - (7:3);

[0010] Ar1 is an aromatic group containing a ketone carbonyl group;

[0011] Ar2 is an aromatic group containing active hydrogen;

[0012] Ar3 is an aromatic group;

[0013] R is a photosensitive group.

[0014] The polyimide precursor provided by this invention contains a ketone carbonyl self-sensitizing group and a group containing an active hydrogen-extracting group in its main chain, both of which can achieve photocrosslinking. Simultaneously, this polyimide precursor also has ester-type photosensitive branches, which readily form a crosslinked structure under the action of photocrosslinking agents, thereby achieving dual photosensitivity. The polyimide prepared based on this polyimide precursor retains the high resolution of ester-type photosensitive polyimides while reducing the proportion of photosensitive branches in the structure, thus reducing the film shrinkage effect after curing and achieving a balance between high resolution and low film thickness shrinkage.

[0015] According to an embodiment of the present invention, Ar1 includes

[0016] At least one of them.

[0017] According to an embodiment of the present invention, Ar2 includes At least one of them.

[0018] According to an embodiment of the present invention, Ar3 includes

[0019] At least one of them.

[0020] According to an embodiment of the present invention, R is

[0021] Wherein, R1 is any one of H and C1-C3 alkyl groups;

[0022] R2 is a C1-C3 divalent alkyl group;

[0023] R3 is a C1-C3 divalent alkyl group.

[0024] According to an embodiment of the present invention, R1 is any one of H and methyl;

[0025] R2 is a C1-C3 divalent alkyl group;

[0026] R3 stands for methylene.

[0027] A second aspect of the present invention provides a method for preparing the polyimide precursor described in the first aspect, the method comprising:

[0028] (1) Dianhydride monomer a and dianhydride monomer b are mixed with an alcohol compound having a photosensitive group to obtain an esterification product;

[0029] (2) The esterification product is subjected to a second mixing treatment with a diamine monomer to obtain polyamic acid;

[0030] (3) The polyamic acid is subjected to an isomerization reaction to obtain an intermediate;

[0031] (4) The intermediate is subjected to a third mixing treatment with the alcohol compound having a photosensitive group to obtain the polyimide precursor;

[0032] Wherein, the dianhydride monomer a has the structure shown in formula (II);

[0033] The dianhydride monomer b has the structure shown in formula (III);

[0034] The diamine monomer has the structure shown in formula (IV);

[0035]

[0036] H2N-Ar2-NH2 (IV).

[0037] This invention introduces the self-sensitizing group ketone carbonyl into the main chain of a polyimide precursor by polymerizing a dianhydride monomer with a ketone carbonyl group, a dianhydride monomer with an aromatic group, an alcohol compound with a photosensitive group, and a diamine monomer with an active hydrogen ablation group. This allows for photocrosslinking with the structure containing the active hydrogen ablation group. Simultaneously, the side chains of this polyimide precursor have ester-type photosensitive branches, which readily form crosslinked structures under the action of photocrosslinking agents. Therefore, this polyimide precursor can achieve dual photosensitivity and reduces the proportion of photosensitive branches in the structure. Consequently, the polyimide film cured from this precursor exhibits weaker film shrinkage, higher photosensitivity, and lower film thickness shrinkage, making it more suitable for chip manufacturing and packaging applications.

[0038] According to an embodiment of the present invention, the molar ratio of dianhydride monomer a to dianhydride monomer b is (3:7)-(7:3).

[0039] According to an embodiment of the present invention, in step (1), the molar ratio of the total amount of dianhydride monomer a and dianhydride monomer b to the molar amount of the alcohol compound having a photosensitive group is 100:(5-50).

[0040] According to embodiments of the present invention, the alcohol compound having a photosensitive group has the structure shown in formula (V) or formula (VI):

[0041]

[0042] According to an embodiment of the present invention, the temperature of the first mixing process is 25-45°C.

[0043] According to an embodiment of the present invention, the time for the first mixing process is 1-4 hours.

[0044] According to an embodiment of the present invention, the molar ratio of the total amount of dianhydride monomer a and dianhydride monomer b to the molar amount of diamine monomer is (1-1.05):1.

[0045] According to an embodiment of the present invention, the temperature of the second mixing process is 0-45°C.

[0046] According to an embodiment of the present invention, the second mixing process takes 10-20 hours.

[0047] According to an embodiment of the present invention, the isomerization reaction includes reacting the polyamic acid with a basic catalyst and an isomerizing agent.

[0048] According to an embodiment of the present invention, the mass ratio of the alkaline catalyst to the polyamic acid is (1-5):100.

[0049] According to an embodiment of the present invention, the mass ratio of the isomerizing agent to the polyamic acid is (1-3):1.

[0050] According to embodiments of the present invention, the alkaline catalyst includes at least one of triethylamine, pyridine, and tetramethylaminopyridine.

[0051] According to embodiments of the present invention, the isomerizing agent comprises dicyclohexylcarbodiimide and / or trifluoroacetic anhydride.

[0052] According to an embodiment of the present invention, the temperature of the isomerization reaction is 25-45°C.

[0053] According to an embodiment of the present invention, the isomerization reaction takes 1-6 hours.

[0054] According to an embodiment of the present invention, in step (4), the mass ratio of the alcohol compound having a photosensitive group to the intermediate is (5-8):1.

[0055] According to an embodiment of the present invention, the temperature of the third mixing process is 35-55°C.

[0056] According to an embodiment of the present invention, the third mixing process takes 10-24 hours.

[0057] A third aspect of the present invention provides a polyimide precursor solution, which is prepared according to the polyimide precursor described in the first aspect or the polyimide precursor obtained according to the method described in the second aspect.

[0058] The polyimide precursor solution is prepared from the aforementioned polyimide precursor.

[0059] A fourth aspect of the present invention provides a method for preparing a polyimide precursor solution, the method comprising:

[0060] The polyimide precursor is mixed with a photoinitiator to obtain the polyimide precursor solution;

[0061] The polyimide precursor is either the polyimide precursor described in the first aspect or the polyimide precursor obtained according to the method described in the second aspect.

[0062] The fifth aspect of the present invention provides a polyimide film, said polyimide film being prepared from the polyimide precursor solution described in the third aspect or the polyimide precursor solution obtained according to the preparation method described in the fourth aspect;

[0063] The polyimide film has the structure shown in formula (VII):

[0064]

[0065] The polyimide film is prepared from a polyimide precursor with high photosensitivity and low film thickness shrinkage, and is suitable for chip manufacturing and packaging.

[0066] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0067] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0068] Figure 1 The infrared spectra of the polyimide precursor and polyimide prepared in Example 1 of the present invention are shown. Detailed Implementation

[0069] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0070] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0071] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0072] To facilitate understanding of the invention, certain technical and scientific terms are specifically defined below. Unless otherwise expressly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0073] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0074] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0075] The term "aromatic group" should be understood as an optionally substituted monocyclic, bicyclic, tricyclic or other polycyclic aromatic ring system having about 5 to about 50 carbon atoms, preferably having 6 to 10 carbon atoms, including but not limited to phenyl, naphthyl, anthracene.

[0076] The term "C1-C3 alkyl" should be understood to refer to a straight-chain or branched saturated monovalent hydrocarbon group having 1, 2, or 3 carbon atoms. The alkyl group is, for example, methyl, ethyl, propyl, isopropyl, or their isomers.

[0077] The term "C1-C3 divalent alkyl" should be understood to refer to a straight-chain or branched saturated divalent hydrocarbon group having 1, 2, or 3 carbon atoms. The divalent alkyl group is, for example, methylene, ethylene, trimethylene, etc.

[0078] According to embodiments of the present invention, a first aspect provides a polyimide precursor having the structure shown in formula (I):

[0079]

[0080] Where, m:n = (3:7) - (7:3);

[0081] Ar1 is an aromatic group containing a ketone carbonyl group;

[0082] Ar2 is an aromatic group containing active hydrogen;

[0083] Ar3 is an aromatic group;

[0084] R is a photosensitive group.

[0085] To achieve high photolithographic resolution, ester-type photosensitive polyimides typically require more than 75% photosensitive branches. However, these branches are removed as small molecules after curing, leading to significant film thickness shrinkage. Therefore, there is a trade-off between high resolution and low film thickness shrinkage in ester-type photosensitive polyimides; both are mutually exclusive. This invention introduces self-sensitizing groups into the ester-type photosensitive polyimide precursor to achieve dual photosensitivity. The self-sensitizing ketone carbonyl group is located on the molecular backbone and crosslinks with the hydrogen-donating structure of the diamine monomer under specific wavelength ultraviolet light excitation. Furthermore, the photosensitive groups on the branches can crosslink with each other. Therefore, the proportion of photosensitive branches in the molecular structure can be reduced to a certain extent, minimizing the film shrinkage effect after curing. This approach retains the high resolution of ester-type photosensitive polyimides while reducing the proportion of photosensitive branches in the structure, thus ensuring a low film thickness shrinkage rate.

[0086] According to a specific embodiment of the present invention, Ar1 is an aromatic group containing a ketone carbonyl group.

[0087] Specifically, Ar1 includes

[0088] At least one of them.

[0089] According to a specific embodiment of the present invention, Ar2 is an aromatic group containing active hydrogen. This allows for crosslinking with a self-sensitized ketone carbonyl group under ultraviolet light excitation at a specific wavelength.

[0090] Specifically, Ar2 includes At least one of the following. In its structure, each carbon atom connected to the main chain has an alkyl group at its adjacent position, and the hydrogen in the alkyl group is reactive, being active hydrogen, which can crosslink with the ketone carbonyl group under ultraviolet light excitation at a specific wavelength.

[0091] According to a specific embodiment of the present invention, Ar3 is an aromatic group. Ar3 may be the same as or different from Ar1. This group may also include other functional groups, which can be selected by those skilled in the art as needed. For example, Ar3 may be an aromatic group containing an ether bond to enhance the toughness of the polyimide precursor.

[0092] Specifically, Ar3 includes

[0093]

[0094] At least one of them.

[0095] According to a specific embodiment of the present invention, in the structure shown in formula (I), m and n represent the degree of polymerization, that is, the number of repeating units. The ratio of m to n represents the ratio of the dianhydride monomer providing Ar1 to the dianhydride monomer providing Ar3, preferably m:n is (3:7)-(7:3), for example 3:7, 4:6, 5:5, 6:4, 7:3, etc.

[0096] According to a specific embodiment of the present invention, R is a photosensitive group, preferably R is...

[0097] Wherein, R1 is any one of H and C1-C3 alkyl groups;

[0098] R2 is a C1-C3 divalent alkyl group;

[0099] R3 is a C1-C3 divalent alkyl group;

[0100] Preferably, R1 is any one of H or methyl;

[0101] R2 is a C1-C3 divalent alkyl group;

[0102] R3 stands for methylene.

[0103] According to embodiments of the present invention, a second aspect provides a method for preparing the polyimide precursor described in the first aspect, the method comprising:

[0104] (1) Dianhydride monomer a and dianhydride monomer b are mixed with an alcohol compound having a photosensitive group to obtain an esterification product;

[0105] Wherein, the dianhydride monomer a has the structure shown in formula (II);

[0106] The dianhydride monomer b has the structure shown in formula (III);

[0107]

[0108] Specifically, this step involves partial esterification reactions of dianhydride monomers a and b with alcohols containing photosensitive groups. Taking dianhydride monomer a as an example, the reaction process is as follows: the dianhydride monomer undergoes ring opening to obtain an esterified product with a carboxyl group at one end and an ester group at the other. The reaction of dianhydride monomer b with an alcohol containing a photosensitive group is similar and will not be described in detail here.

[0109]

[0110] According to specific embodiments of the present invention, the molar ratio of dianhydride monomer a to dianhydride monomer b is not particularly limited, and those skilled in the art can choose according to actual needs. As some specific examples, the molar ratio of dianhydride monomer a to dianhydride monomer b is (3:7)-(7:3), such as 3:7, 4:6, 5:5, 6:4, 7:3, etc.

[0111] According to specific embodiments of the present invention, the dianhydride monomer a includes, but is not limited to, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA, CAS No.: 2421-28-5). (5,11-dihydrofurano[4',3':6,7]anthra[3,2-c]furan-1,3,5,7,9-pentaone, purchased from Alfaesa (China) Chemical Co., Ltd.) (5-({3-[(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)carbonyl]phenyl}carbonyl)-2-benzofuran-1,3-dione, purchased from Alfaesa (China) Chemical Co., Ltd.) (5-{[3-({3-[(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)oxy]phenyl}carbonyl)phenyl]oxy}-2-benzofuran-1,3-dione, purchased from Alfaesa (China) Chemical Co., Ltd.) (Furano[4',3':6,7]anthra[3,2-c]furan-1,3,5,7,9,11-hexadecanone, purchased from Alfaesa (China) Chemical Co., Ltd.).

[0112] According to specific embodiments of the present invention, the dianhydride monomer b includes, but is not limited to, biphenyl ether dianhydride (ODPA, CAS No.: 1823-59-2), pyromellitic dianhydride (PMDA, CAS No.: 89-32-7), biphenyl dianhydride (BPDA, CAS No.: 2420-87-3), 4,4'-terephthalodioxydiphthalic anhydride (HQDA, CAS No.: 17828-53-4), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA, CAS No.: 2421-28-5), and 5,11-dihydrofurano[4',3':6,7]anthra[3,2-c]furan-1,3,5,7,9-pentaone (purchased from [unclear - likely a company name]). Faeza (China) Chemical Co., Ltd.), 5-({3-[(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)carbonyl]phenyl}carbonyl)-2-benzofuran-1,3-dione (purchased from Faeza (China) Chemical Co., Ltd.), 5-{[3-({3-[(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)oxy]phenyl}carbonyl)phenyl]oxy}-2-benzofuran-1,3-dione (purchased from Faeza (China) Chemical Co., Ltd.), furano[4',3':6,7]anthra[3,2-c]furan-1,3,5,7,9,11-hexane (purchased from Faeza (China) Chemical Co., Ltd.).

[0113] According to specific embodiments of the present invention, the amount of the alcohol compound with photosensitive group added is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the molar ratio of the total amount of dianhydride monomer a and dianhydride monomer b to the molar amount of the alcohol compound with photosensitive group is 100:(5-50), such as 100:5, 100:10, 100:15, 100:20, 100:25, 100:30, 100:35, 100:40, 100:45, 100:50, etc.

[0114] According to a specific embodiment of the present invention, the alcohol compound having a photosensitive group has the structure shown in formula (V) or formula (VI):

[0115]

[0116] Preferably, the alcohol compound having a photosensitive group is allyl alcohol, methyl methacrylate, ethyl methacrylate, hydroxypropyl methacrylate, ethyl acrylate, etc.

[0117] According to specific embodiments of the present invention, the temperature and time of the first mixing treatment are not particularly limited, and those skilled in the art can select them according to actual needs. As some specific examples, the temperature of the first mixing treatment can be 25-45℃, such as 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, etc. The time of the first mixing treatment is 1-4 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, etc.

[0118] (2) The esterification product is subjected to a second mixing treatment with a diamine monomer to obtain polyamic acid;

[0119] The diamine monomer has the structure shown in formula (IV):

[0120] H2N-Ar2-NH2 (IV).

[0121] Specifically, the following reaction occurs in this step:

[0122]

[0123] According to specific embodiments of the present invention, the amount of diamine monomer added is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the molar ratio of the total amount of dianhydride monomer a and dianhydride monomer b to the molar amount of diamine monomer is (1-1.05):1, for example 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, etc.

[0124] According to specific embodiments of the present invention, the diamine monomers include, but are not limited to, 3,3'-dimethylbenzidine (CAS No.: 119-93-7), 3,3'-diethylbenzidine (CAS No.: 76787-87-6), 3,3',5,5'-tetramethylbenzidine (CAS No.: 54827-17-7), and 3,3',5,5'-tetraethylbenzidine (CAS No.: 2095-04-7).

[0125] According to specific embodiments of the present invention, the temperature and time of the second mixing treatment are not particularly limited, and those skilled in the art can select them according to actual needs. As some specific examples, the temperature of the second mixing treatment is 0-45℃, such as 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, etc. The time of the second mixing treatment is 10-20h, such as 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, etc.

[0126] (3) The polyamic acid is subjected to an isomerization reaction to obtain an intermediate.

[0127] Specifically, the isoimide reaction includes reacting the second intermediate with a basic catalyst and an isomerizing agent to obtain polyisoimide.

[0128] According to specific embodiments of the present invention, the type of alkaline catalyst is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the alkaline catalyst includes, but is not limited to, triethylamine, pyridine, and tetramethylaminopyridine.

[0129] According to specific embodiments of the present invention, the type of isomerizing reagent is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the isomerizing reagent includes, but is not limited to, dicyclohexylcarbodiimide and trifluoroacetic anhydride.

[0130] Specifically, taking the isomerizing reagent trifluoroacetic anhydride as an example, this step involves the following reaction:

[0131]

[0132] According to specific embodiments of the present invention, the amount of alkaline catalyst added is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the mass ratio of the alkaline catalyst to the polyamic acid is (1-5):100, such as 1:100, 2:100, 3:100, 4:100, 5:100, etc.

[0133] According to specific embodiments of the present invention, the amount of the isomerizing agent added is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the mass ratio of the isomerizing agent to the polyamic acid is (1-3):1, for example 1:1, 2:1, 3:1, etc.

[0134] According to specific embodiments of the present invention, the temperature and time of the isomerization reaction are not particularly limited, and those skilled in the art can select them according to actual needs. As some specific examples, the temperature of the isomerization reaction is 25-45°C, such as 25°C, 30°C, 35°C, 40°C, 45°C, etc., and the time of the isomerization reaction is 1-6h, such as 1h, 2h, 3h, 4h, 5h, 6h, etc.

[0135] (4) The intermediate is mixed with the alcohol compound having a photosensitive group in a third mixing process to obtain the polyimide precursor.

[0136] Specifically, the intermediate is mixed with an alcohol compound having a photosensitive group to achieve complete esterification, as shown in the following reaction:

[0137]

[0138] According to a specific embodiment of the present invention, in this step, the amount of the alcohol compound with photosensitive group added is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the mass ratio of the alcohol compound with photosensitive group to the intermediate is (5-8):1, for example 5:1, 6:1, 7:1, 8:1, etc.

[0139] According to specific embodiments of the present invention, the temperature and time of the third mixing treatment are not particularly limited, and those skilled in the art can select them according to actual needs. As some specific examples, the temperature of the third mixing treatment is 35-55℃, such as 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, etc. The time of the third mixing treatment is 10-24h, such as 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, etc.

[0140] According to a specific embodiment of the present invention, the method may further include, after the third mixing treatment, adding the obtained product to deionized water under low temperature conditions to obtain a precipitate, washing it, and then drying and filtering it under reduced pressure to obtain the final product. The low temperature, relative to the temperature of the third mixing treatment, may include room temperature. The precipitate is a white flocculent solid. The washing solution may be deionized water or an alcohol, such as methanol, ethanol, isopropanol, etc.

[0141] A third aspect of the present invention provides a polyimide precursor solution, which is prepared according to the polyimide precursor described in the first aspect or the polyimide precursor obtained according to the method described in the second aspect.

[0142] A fourth aspect of the present invention provides a method for preparing a polyimide precursor solution, the method comprising:

[0143] The polyimide precursor is mixed with a photoinitiator to obtain the polyimide precursor solution;

[0144] The polyimide precursor is either the polyimide precursor described in the first aspect or the polyimide precursor obtained according to the method described in the second aspect.

[0145] According to a specific embodiment of the present invention, the preparation method may further include: dissolving the polyimide precursor in a solvent, adding a photoinitiator under light-protected conditions, to obtain the polyimide precursor solution. The solvent is preferably an organic solvent, including but not limited to N-methylpyrrolidone (NMP), dimethylacetamide (DMAC), γ-butyrolactone, etc. The type of photoinitiator is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific examples, the photoinitiator may be 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl oxime).

[0146] According to specific embodiments of the present invention, the preparation method may further involve mixing the polyimide precursor with a photoinitiator and other additives, such as photosensitizers, photocrosslinking agents, stabilizers, etc., with the solid content of the adhesive solution being 20%-40%.

[0147] The fifth aspect of the present invention provides a polyimide film, which is prepared according to the polyimide precursor solution described in the third aspect or the polyimide precursor solution obtained according to the preparation method described in the fourth aspect;

[0148] The polyimide film has the structure shown in formula (VII):

[0149]

[0150] The polyimide film is prepared from a polyimide precursor with high photosensitivity and low film thickness shrinkage, and is suitable for chip manufacturing and packaging.

[0151] According to specific embodiments of the present invention, the preparation method of the polyimide film is not particularly limited, and those skilled in the art can choose according to actual needs. As some specific examples, the preparation method of the polyimide film includes:

[0152] The polyimide precursor solution is coated onto the substrate surface, and then exposed and photocured to obtain the polyimide film.

[0153] According to a specific embodiment of the present invention, a polyimide precursor solution can be dropped onto a silicon wafer, spin-coated, baked on a hot plate to set the solution, and exposed under an exposure machine. Cyclopentanone can be used as the developer and propylene glycol monomethyl ether ester as the cleaning solution. After cleaning, the dried silicon wafer is placed in a nitrogen atmosphere for curing to obtain a polyimide film.

[0154] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0155] Example 1

[0156] Preparation of polyimide precursors:

[0157] (1) Purge dry nitrogen gas into a 500 mL three-necked flask and add 40 mL of dry N-methylpyrrolidone, followed by 3.22 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 3.10 g of biphenyl ether dianhydride. After they are fully dissolved, keep the solution temperature at 25 °C and slowly add 0.26 g of hydroxyethyl methacrylate. Raise the temperature to 40 °C and continue the reaction for 2 h.

[0158] (2) Subsequently, 4.25 g of 3,3'-dimethylbenzidine was dissolved in 20 mL of dry N-methylpyrrolidone in a dry beaker. This diamine mixture was then added dropwise to a three-necked flask under ice bath conditions to obtain a viscous polyamic acid solution. The reaction was carried out at 25 °C for 10 h.

[0159] (3) Slowly add 0.2 g of triethylamine to the obtained polyamic acid solution, and then slowly add 15 g of trifluoroacetic anhydride to the mixed solution. Stir vigorously for 4 h to obtain a polyisoimide solution.

[0160] (4) Add 62g of hydroxyethyl methacrylate to the above solution and raise the temperature to 55℃, and react for 12h;

[0161] (5) After the reaction is completed, cool to room temperature, add the solution dropwise into deionized water, and a white flocculent solid precipitates out. Filter under reduced pressure to obtain the solid and wash with a large amount of deionized water until pH=7. Then wash the resin solid with an appropriate amount of ethanol, dry the solid in vacuum, and the white powder obtained after constant weight is the polyimide precursor.

[0162] Preparation of photosensitive polyimide precursor solution:

[0163] 10g of the aforementioned polyimide precursor was dissolved in 25g of N-methylpyrrolidone. Under light-protected conditions, 0.5g of 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl oxime), 0.02g of 4,4'-bis(N,N-dimethylamino)benzophenone, 0.6g of ureapropyltriethoxysilane methanol solution, and 2g of triethylene glycol diacrylate were added while stirring. After stirring for 2 hours, the mixture was filtered through a 0.2μm filter to obtain the polyimide precursor solution.

[0164] The differences between Examples 2-50, Comparative Examples 1-4 and Example 1 are shown in Table 1.

[0165] The photosensitivity test specifically includes:

[0166] 2.5 mL of polyimide precursor solution was dropped onto a 6-inch silicon wafer and coated by spin coating at 3000 rpm. The wafer was then baked on a hot plate at 90°C for 150 seconds to set the solution. Finally, the wafer was exposed to 200 mJ / cm² using an I-line exposure machine. 2 Exposure was performed using cyclopentanone as the developer and propylene glycol monomethyl ether ester as the cleaning solution. After cleaning, the dried silicon wafer was cured in a nitrogen atmosphere at 350°C. The cured PSPI film pattern was analyzed using an optical microscope and a scanning electron microscope. The resolution of the material was defined as the smallest size in which the pattern remained intact and clear.

[0167] The film thickness shrinkage rate test is specifically as follows:

[0168] 2.5 mL of polyimide precursor solution was dropped onto a 6-inch silicon wafer and coated by spin coating at 3000 rpm. The solution was then baked on a hot plate at 90°C for 150 seconds to set the adhesive. The thickness of the film on the silicon wafer was measured using an optical reflectance film thickness gauge and recorded as n1. Subsequently, the silicon wafer was cured in a nitrogen atmosphere at 350°C, and the thickness of the cured film was recorded as n2. The film thickness shrinkage rate was obtained by formula Y = (n1-n2) / n1*100%.

[0169] The test results are shown in Table 2. As can be seen from the test results in Table 2, the photosensitive polyimide prepared by the method provided by the present invention can achieve both strong photosensitivity and low film shrinkage.

[0170] Table 1

[0171]

[0172]

[0173]

[0174]

[0175]

[0176] Continued from Table 1

[0177]

[0178]

[0179]

[0180]

[0181]

[0182]

[0183]

[0184]

[0185] The " / " indicates that it is not present.

[0186] Table 2

[0187]

[0188]

[0189]

[0190]

[0191] Analysis of experimental results:

[0192] As shown in Table 2, the polyimide film prepared by the method provided by the present invention can achieve both high resolution and low film thickness shrinkage.

[0193] Specifically, compared with Example 1, Examples 2-4 only changed the molar ratio of dianhydride monomer a and dianhydride monomer b (the molar ratios of dianhydride monomer a and dianhydride monomer b in Examples 1-4 were 1:1, 3:7, 2:3, and 7:3, respectively); compared with Example 1, Examples 5-7 only changed the ratio of the total molar amount of dianhydride monomer a and dianhydride monomer b to the molar amount of the alcohol compound with the photosensitive group (the ratios in Examples 1 and 5-7 were 100:10, 100:5, 100:20, and 100:50, respectively); compared with Example 1, Examples 8-9 only changed the temperature of the first mixing treatment (the temperature of the first mixing treatment in Examples 1 and 8-9 was 100:10, 100:5, 100:20, and 100:50, respectively). The temperatures for the first mixing treatment were 25°C, 35°C, and 45°C, respectively. Examples 10-11 differed from Example 1 only in the duration of the first mixing treatment (the durations of the first mixing treatment in Examples 1 and 8-9 were 2 hours, 1 hour, and 4 hours, respectively). Examples 12-13 differed from Example 1 only in the molar ratio of the total molar amount of dianhydride monomer a and dianhydride monomer b to the molar ratio of the diamine monomer (the molar ratios in Examples 1 and 12-13 were 1:1, 1.03:1, and 1.05:1, respectively). Examples 14-15 differed from Example 1 only in the temperature of the second mixing treatment (the temperatures of the second mixing treatment in Examples 1 and 14-15 were 25°C, 35°C, and 45°C, respectively). Examples 16-17 were at 25°C, 10°C, and 45°C, respectively. Compared to Example 1, Examples 16-17 only differed in the duration of the second mixing treatment (10h, 15h, and 20h in Examples 1, 16-17, and 18-19, respectively). Compared to Example 1, Examples 18-19 only differed in the mass ratio of the alkaline catalyst to polyamic acid (1.85:100, 3:100, and 5:100 in Examples 1, 18-19, and 18-19, respectively). Compared to Example 1, Examples 20-21 only differed in the mass ratio of the isomerizing agent to polyamic acid (1.85:100, 3:100, and 5:100 in Examples 1, 20-21, and 20-21, respectively). The mass ratios of polyamic acid were 1.39:1, 2:1, and 3:1, respectively. Examples 22-23 differed from Example 1 only in the temperature of the isomerization reaction (25°C, 35°C, and 45°C in Examples 1 and 22-23, respectively). Examples 24-25 differed from Example 1 only in the time of the isomerization reaction (4h, 1h, and 6h in Examples 1 and 24-25, respectively). Examples 26-27 differed from Example 1 only in the mass ratio of the alcohol compound with the photosensitive group to the intermediate in step four (5:1 in Examples 1 and 26-27, respectively).Examples 28-29 differ from Example 1 only in the temperature of the third mixing treatment (55°C, 35°C, and 45°C in Examples 1, 28-29, respectively); Examples 30-32 differ from Example 1 only in the time of the third mixing treatment (12h, 10h, 20h, and 24h in Examples 1, 30-32, respectively); Examples 33-35 and 50 differ from Example 1 only in the type of dianhydride monomer b; Examples 36-39 differ only in the type of alcohol compound with a photosensitive group; Examples 40-42 differ from Example 1 only in the type of diamine monomer; Examples 43-44 differ from Example 1 only in the type of basic catalyst; Example 45 differs from Example 1 only in the type of isomerizing agent; Examples 46-49 differ from Example 1 only in the type of dianhydride monomer a.

[0194] All the above embodiments yielded photosensitive polyimide films that achieved both high resolution and low film thickness shrinkage.

[0195] Compared to Example 1, Comparative Example 1 lacks dianhydride monomer a, meaning it does not use a dianhydride monomer containing a ketone carbonyl group. Therefore, crosslinking cannot be achieved through self-sensitizing groups, resulting in lower resolution (25 μm for Comparative Example 1, 5 μm for Example 1). Simultaneously, the film thickness shrinkage rate is larger (23.7% in Comparative Example 1, 18% in Example 1). This is because more branched ester groups were introduced, and these ester molecules were removed during curing, leading to significant film thickness shrinkage. Comparative Example 3 (the technical solution of Example 5 in CN111303417) prepares a self-sensitizing photosensitive polyimide film using a diamine monomer with a ketone carbon group, a diamine monomer containing an active hydrogen that can be abstracted, and a dianhydride monomer. It does not introduce ester-type photosensitive branches, therefore its film thickness shrinkage rate is lower than Example 1, but some resolution is sacrificed.

[0196] Compared to Example 1, Comparative Examples 2 and 4 used diamine monomers that do not contain readily available active hydrogen. Since diamine monomers lack active hydrogen, they cannot achieve crosslinking through self-sensitizing groups, resulting in lower resolution (25 μm for Comparative Examples 2 and 4, and 5 μm for Example 1). Furthermore, the precursors obtained in Comparative Examples 2 and 4 had a higher proportion of branched ester groups, leading to the removal of ester molecules during curing and resulting in significant film thickness shrinkage (22.5% and 23.2% for Comparative Examples 2 and 4, respectively, compared to 18% for Example 1).

[0197] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0198] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A polyimide precursor, characterized in that, The polyimide precursor has the structure shown in formula (I): Where, m:n = (3:7) - (7:3); Ar1 is an aromatic group containing a ketone carbonyl group; Ar2 is an aromatic group containing active hydrogen; Ar3 is an aromatic group; R is a photosensitive group.

2. The polyimide precursor according to claim 1, characterized in that, Ar1 includes At least one of them.

3. The polyimide precursor according to claim 1, characterized in that, Ar2 includes At least one of them.

4. The polyimide precursor according to claim 1, characterized in that, Ar3 includes At least one of them.

5. The polyimide precursor according to claim 1, characterized in that, R is Wherein, R1 is any one of H and C1-C3 alkyl groups; R2 is a C1-C3 divalent alkyl group; R3 is a C1-C3 divalent alkyl group; Optionally, R1 can be either H or methyl. R2 is a C1-C3 divalent alkyl group; R3 stands for methylene.

6. A method for preparing the polyimide precursor according to any one of claims 1-5, characterized in that, include: (1) Dianhydride monomer a and dianhydride monomer b are mixed with an alcohol compound having a photosensitive group to obtain an esterification product; (2) The esterification product is subjected to a second mixing treatment with a diamine monomer to obtain polyamic acid; (3) The polyamic acid is subjected to an isomerization reaction to obtain an intermediate; (4) The intermediate is subjected to a third mixing treatment with the alcohol compound having a photosensitive group to obtain the polyimide precursor; Wherein, the dianhydride monomer a has the structure shown in formula (II); The dianhydride monomer b has the structure shown in formula (III); The diamine monomer has the structure shown in formula (IV); H2N-Ar2—NH2 (IV).

7. The method according to claim 6, characterized in that, The molar ratio of dianhydride monomer a to dianhydride monomer b is (3:7)-(7:3); Optionally, in step (1), the molar ratio of the total amount of dianhydride monomer a and dianhydride monomer b to the molar amount of the alcohol compound having a photosensitive group is 100:(5-50). Optionally, the alcohol compound having a photosensitive group has the structure shown in formula (V) or formula (VI): Optionally, the temperature of the first mixing treatment is 25-45°C; Optionally, the first mixing process takes 1-4 hours.

8. The method according to claim 6, characterized in that, The molar ratio of the total amount of dianhydride monomer a and dianhydride monomer b to the molar amount of the diamine monomer is (1-1.05):1; Optionally, the temperature of the second mixing treatment is 0-45°C; Optionally, the second mixing process takes 10-20 hours.

9. The method according to claim 6, characterized in that, The isomerization reaction includes reacting the polyamic acid with a basic catalyst and an isomerization reagent; Optionally, the mass ratio of the alkaline catalyst to the polyamic acid is (1-5):100; Optionally, the mass ratio of the isomerizing agent to the polyamic acid is (1-3):1; Optionally, the alkaline catalyst includes at least one of triethylamine, pyridine, and tetramethylaminopyridine; Optionally, the isomerizing agent comprises dicyclohexylcarbodiimide and / or trifluoroacetic anhydride; Optionally, the isomerization reaction is carried out at a temperature of 25-45°C; Optionally, the isomerization reaction takes 1-6 hours.

10. The method according to claim 6, characterized in that, In step (4), the mass ratio of the alcohol compound with the photosensitive group to the intermediate is (5-8):1; Optionally, the temperature of the third mixing treatment is 35-55°C; Optionally, the third mixing process takes 10-24 hours.

11. A polyimide precursor liquid, characterized in that, The polyimide precursor solution is obtained from the polyimide precursor according to any one of claims 1-5 or the polyimide precursor obtained by the method according to any one of claims 6-10.

12. A method for preparing a polyimide precursor solution, characterized in that, include: The polyimide precursor is mixed with a photoinitiator to obtain the polyimide precursor solution; The polyimide precursor is the polyimide precursor according to any one of claims 1-5 or the polyimide precursor obtained by the method according to any one of claims 6-10.

13. A polyimide film, characterized in that, The polyimide film is prepared according to the polyimide precursor solution according to claim 11 or the polyimide precursor solution obtained by the preparation method according to claim 12; The polyimide film has the structure shown in formula (VII):

Images