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 polyimide precursor has a structure shown as a formula (I), wherein m: n = x: y = (3: 7)-(7: 3); m: x = n: y = (1: 9)-(3: 2); ar1 is an aliphatic group; ar2 is an aromatic group containing a nitrogen heterocyclic ring; ar3 is a first aromatic group; ar4 is a second aromatic group; r is a photosensitive group. The polyimide film prepared from the polyimide precursor has low thermal expansion coefficient, high resolution and thermal stability.

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. Among them, ester-type photosensitive polyimides have become the mainstream negative resist due to their higher glass transition temperature and better photolithographic resolution. However, most ester-type photosensitive polyimide resins contain aromatic benzene ring structures, resulting in a generally high coefficient of thermal expansion (CTE). Metal substrates, on the other hand, generally have a lower CTE. This difference in CTE can easily lead to warping or even detachment of the PSPI film during subsequent processes, significantly limiting its application.

[0004] Existing technologies achieve a low coefficient of thermal expansion (CTE) while enabling development in alkaline developers by simultaneously introducing carboxyl and trifluoromethyl groups into the resin molecule. However, the introduction of fluorine groups reduces the mechanical properties of the PI film, making it unsuitable for high-strength chip packaging applications. Furthermore, high-purity fluorine monomers are generally expensive, limiting large-scale industrial applications. Alternatively, a positive PSPI resin with a low CTE can be prepared by introducing hydroxyl groups followed by protection with tert-butyloxycarbonyl groups. This resin can be developed in aqueous solutions; however, the resin obtained through high-temperature chemical imidization has a low molecular weight, and the reaction is difficult to control, hindering large-scale industrial production. Another method involves synthesizing a low CTE PSPI using a capped polyimide salt and a photoinitiator, achieving a CTE as low as 11 ppm. However, its photosensitivity and resolution are inferior to ester-type PSPI, with a low CTE at 700 mJ / cm². 2The resolution is reduced to only 20 μm. Furthermore, by introducing oligomeric silsesquioxane functional groups into the end groups of the polyimide polymer chain and the side chains of the diamine units, the PI material can exhibit lower dielectric constants and coefficients of thermal expansion. However, the introduction of oligomeric silsesquioxane functional groups increases the difficulty of the PI polymerization reaction and affects its storage stability; therefore, this method is not suitable for large-scale preparation.

[0005] Therefore, there is an urgent need to provide a photosensitive polyimide that combines low coefficient of thermal expansion, high resolution, and thermal stability. 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 a balance of low coefficient of thermal expansion, high resolution, and thermal stability.

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

[0008]

[0009] Among them, m:n=x:y=(3:7)-(7:3); m:x=n:y=(1:9)-(3:2);

[0010] Ar1 is an aliphatic group;

[0011] Ar2 is an aromatic group containing a nitrogen heterocycle;

[0012] Ar3 is the first aromatic group;

[0013] Ar4 is the second aromatic group;

[0014] R is a photosensitive group.

[0015] The polyimide precursor provided by this invention contains a nitrogen-containing heterocyclic diamine and a highly flexible aliphatic dianhydride in its main chain, resulting in a resin structure with a low coefficient of thermal expansion. Simultaneously, the addition of aromatic dianhydride and aromatic diamine mitigates the problem of PI film losing mechanical strength after curing due to the introduction of aliphatic dianhydride. Furthermore, this polyimide precursor also possesses ester-type photosensitive branches, which readily form cross-linked structures under the action of photocrosslinking agents, thereby achieving photosensitivity. Therefore, the polyimide prepared based on this polyimide precursor retains the high resolution of ester-type photosensitive polyimides while also achieving a low coefficient of thermal expansion and thermal stability.

[0016] According to an embodiment of the present invention, Ar1 includes

[0017] At least one of them.

[0018] According to an embodiment of the present invention, Ar2 includes

[0019] At least one of them.

[0020] According to an embodiment of the present invention, Ar3 includes

[0021] At least one of them.

[0022] According to an embodiment of the present invention, Ar4 includes

[0023]

[0024] At least one of them.

[0025] According to an embodiment of the present invention, R is Wherein, R1 is any one of H and C1-C3 alkyl groups;

[0026] R2 is a C1-C3 divalent alkyl group.

[0027] According to an embodiment of the present invention, R1 is any one of H and methyl;

[0028] R2 is a C1-C3 divalent alkyl group.

[0029] A second aspect of the present invention provides a method for preparing the polyimide precursor described in the first aspect, the method comprising:

[0030] The dianhydride monomers a and b are first mixed with an alcohol compound having a photosensitive group to obtain an esterified product.

[0031] The esterification product is subjected to a second mixing treatment with diamine monomer a and diamine monomer b to obtain polyamic acid;

[0032] The polyamic acid was subjected to an isomerization reaction to obtain an intermediate;

[0033] The intermediate is subjected to a third mixing treatment with the alcohol compound having a photosensitive group to obtain the polyimide precursor;

[0034] Wherein, the dianhydride monomer a has the structure shown in formula (II);

[0035] The dianhydride monomer b has the structure shown in formula (III);

[0036] The diamine monomer a has the structure shown in formula (IV);

[0037] The diamine monomer b has the structure shown in formula (V);

[0038]

[0039] H2N-Ar2-NH2 formula (IV); H2N-Ar4-NH2 formula (V).

[0040] This invention copolymerizes an aromatic diamine with a nitrogen-containing heterocyclic ring with a highly flexible aliphatic dianhydride, resulting in a resin structure with a low coefficient of thermal expansion. Simultaneously, the introduction of aromatic dianhydride and aromatic diamine into the structure improves its mechanical properties. Furthermore, the side chains of the polyimide precursor possess ester-type photosensitive branches, readily forming cross-linked structures under the action of photocrosslinking agents. Therefore, the polyimide prepared using this polyimide precursor can achieve a balance of low coefficient of thermal expansion, high resolution, and thermal stability. Moreover, this preparation method allows for a wide selection of monomer types, not limited to fluorinated monomers, and avoids chemical imidization processes, ensuring cost control and feasibility for industrial production.

[0041] According to an embodiment of the present invention, the molar ratio of dianhydride monomer a to dianhydride monomer b is (1:9)-(3:2).

[0042] 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 the alcohol compound having a photosensitive group in the first mixing process is 100:(5-50).

[0043] According to an embodiment of the present invention, the alcohol compound having a photosensitive group has the structure shown in formula (VI):

[0044]

[0045] According to an embodiment of the present invention, the temperature of the first mixing process is 25-45°C.

[0046] According to an embodiment of the present invention, the time for the first mixing process is 1-4 hours.

[0047] According to an embodiment of the present invention, the molar ratio of diamine monomer a to diamine monomer b is (3:7)-(7:3).

[0048] According to an embodiment of the present invention, the molar ratio of the total molar amount of dianhydride monomer a and dianhydride monomer b to the total molar amount of diamine monomer a and diamine monomer b is (1-1.05):1.

[0049] According to an embodiment of the present invention, the temperature of the second mixing process is 0-45°C.

[0050] According to an embodiment of the present invention, the second mixing process takes 10-20 hours.

[0051] According to an embodiment of the present invention, the isomerization reaction includes reacting the polyamic acid with a basic catalyst and an isomerizing agent.

[0052] According to an embodiment of the present invention, the mass ratio of the alkaline catalyst to the polyamic acid is (1-5):100.

[0053] According to an embodiment of the present invention, the mass ratio of the isomerizing agent to the polyamic acid is (1-3):1.

[0054] According to embodiments of the present invention, the alkaline catalyst includes at least one of triethylamine, pyridine, and tetramethylaminopyridine.

[0055] According to embodiments of the present invention, the isomerizing agent comprises dicyclohexylcarbodiimide and / or trifluoroacetic anhydride.

[0056] According to an embodiment of the present invention, the temperature of the isomerization reaction is 25-45°C.

[0057] According to an embodiment of the present invention, the isomerization reaction takes 1-6 hours.

[0058] According to an embodiment of the present invention, the mass ratio of the alcohol compound having a photosensitive group to the intermediate in the third mixing process is (5-8):1.

[0059] According to an embodiment of the present invention, the temperature of the third mixing process is 35-55°C.

[0060] According to an embodiment of the present invention, the third mixing process takes 10-24 hours.

[0061] 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.

[0062] A fourth aspect of the present invention provides a method for preparing a polyimide precursor solution, the method comprising:

[0063] The polyimide precursor is mixed with a photoinitiator to obtain the polyimide precursor solution;

[0064] 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.

[0065] 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;

[0066] The polyimide film has the structure shown in formula (VII):

[0067]

[0068] The polyimide film is prepared from the aforementioned polyimide precursor solution and has a low coefficient of thermal expansion, low stress, high mechanical strength, and high thermal stability, making it suitable for chip manufacturing and packaging.

[0069] 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

[0070] 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:

[0071] Figure 1 The infrared spectrum of the polyimide precursor prepared in Example 1 of this invention is shown;

[0072] Figure 2 The hydrogen NMR spectrum of the polyimide precursor prepared in Example 1 of this invention is shown. Detailed Implementation

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] In this document, the terms “comprising” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0078] 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.

[0079] The term "aliphatic group" should be understood as a chain-like structure of carbon atoms, including saturated and unsaturated groups. It is a general term for chain hydrocarbons (open-chain hydrocarbons) and cyclic hydrocarbons other than aromatic hydrocarbons and their derivatives, including but not limited to methyl, ethyl, propyl, etc.

[0080] 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, including but not limited to phenyl, naphthyl, and anthracene.

[0081] 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.

[0082] 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, such as methylene, ethylene, trimethylene, etc.

[0083] According to embodiments of the present invention, a first aspect provides a polyimide precursor having the structure shown in formula (I):

[0084]

[0085] Among them, m:n=x:y=(3:7)-(7:3); m:x=n:y=(1:9)-(3:2);

[0086] Ar1 is an aliphatic group;

[0087] Ar2 is an aromatic group containing a nitrogen heterocycle;

[0088] Ar3 is the first aromatic group;

[0089] Ar4 is the second aromatic group;

[0090] R is a photosensitive group.

[0091] Current PSPI materials, while pursuing low coefficients of thermal expansion, often sacrifice other key properties such as mechanical strength, photosensitivity, and resolution, or face challenges such as high production costs and difficult fabrication, failing to fully meet the needs of high-end chip manufacturing and packaging. This invention introduces aliphatic dianhydrides and nitrogen heterocyclic structures to obtain a resin structure with a low coefficient of thermal expansion, while retaining the aromatic ring structure in a blended form, endowing the photosensitive polyimide with sufficient mechanical strength. This approach retains the high resolution of ester-type photosensitive polyimide while also considering low coefficients of thermal expansion and thermal stability.

[0092] According to a specific embodiment of the present invention, Ar1 is an aliphatic group with high flexibility, which is beneficial for forming a resin structure with a low coefficient of thermal expansion.

[0093] Specifically, Ar1 includes, but is not limited to,

[0094] According to a specific embodiment of the present invention, Ar2 is an aromatic group containing a nitrogen heterocycle. It can be combined with aliphatic groups with high flexibility to obtain a resin structure with a low coefficient of thermal expansion.

[0095] Specifically, Ar2 includes, but is not limited to,

[0096] According to a specific embodiment of the present invention, Ar3 is a first aromatic group used to adjust the mechanical strength of the resin structure. Those skilled in the art can select the appropriate group as needed; for example, Ar3 may be an aromatic group containing an ether bond to further enhance the toughness of the polyimide precursor.

[0097] Specifically, Ar3 includes, but is not limited to,

[0098]

[0099] According to a specific embodiment of the present invention, Ar4 is a second aromatic group used to adjust the mechanical strength of the resin structure. Those skilled in the art can select the appropriate group as needed; for example, Ar4 can be an aromatic group containing an ether bond to further enhance the toughness of the polyimide precursor.

[0100] Specifically, Ar4 includes, but is not limited to,

[0101]

[0102] According to a specific embodiment of the present invention, in the structure shown in formula (I), m, n, x and y represent the degree of polymerization, that is, the number of each repeating unit, where m:n = x:y = (3:7)-(7:3); m:x = n:y = (1:9)-(3:2), which is determined by the feeding ratio of diamine and dianhydride, etc.

[0103] According to a specific embodiment of the present invention, R is a photosensitive group, preferably R is...

[0104] Wherein, R1 is any one of H and C1-C3 alkyl groups;

[0105] R2 is a C1-C3 divalent alkyl group;

[0106] Preferably, R1 is any one of H or methyl.

[0107] R2 is a C1-C3 divalent alkyl group.

[0108] 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:

[0109] (1) Dianhydride monomer a and dianhydride monomer b are mixed with an alcohol compound having a photosensitive group to obtain an esterification product;

[0110] Wherein, the dianhydride monomer a has the structure shown in formula (II);

[0111] The dianhydride monomer b has the structure shown in formula (III);

[0112]

[0113] Specifically, this step involves a partial esterification reaction between dianhydride monomer a, dianhydride monomer b, and an alcohol compound with a photosensitive group. 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 between dianhydride monomer b and the alcohol compound with a photosensitive group is similar and will not be described in detail here.

[0114]

[0115] 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 (1:9)-(3:2), such as 1:9, 2:8, 3:7, 4:6, etc.

[0116] According to specific embodiments of the present invention, the dianhydride monomer a includes, but is not limited to, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA, CAS No.: 4415-87-6), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA, CAS No.: 2754-41-8), 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride (CAS No.: 64198-16-9), and 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride (CAS No.: 137820-87). -2), 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride (CAS No.: 15894-21-0), 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride (custom compound, purchased from Alfaeza (China) Chemical Co., Ltd.), 3,4-dicarboxy-1-cyclohexylsuccinic dianhydride (custom compound, purchased from Alfaeza (China) Chemical Co., Ltd.), 2,3,5-tricarboxycyclopentylacetic acid dianhydride (CAS No.: 87078-75-9), cyclopentanetetracarboxylic acid dianhydride (CAS No.: 6053-68-5).

[0117] According to specific embodiments of the present invention, the dianhydride monomer b includes, but is not limited to, pyromellitic dianhydride (PMDA, CAS No.: 89-32-7), 3,3',4,4'-biphenyltetracarboxylic dianhydride (CAS No.: 2420-87-3), 2,3,3',4'-biphenyltetracarboxylic dianhydride (CAS No.: 36978-41-3), 2,3,2',3'-biphenyltetracarboxylic dianhydride (custom compound, purchased from Alfaea (China) Chemical Co., Ltd.), 3,3',4,4'-triphenyltetracarboxylic dianhydride (custom compound, purchased from Alfaea (China) Chemical Co., Ltd.), 3,3',4,4'-oxophthalic dianhydride (CAS No.: 1823-59-2, custom compound, purchased from Alfaea (China) Chemical Co., Ltd.), and 2,3,3',4'-oxophthalic dianhydride (CAS No.: 50662-95-). 8) 2,3,2',3'-Oxadiphthalic dianhydride (custom compound, purchased from Alfaeza (China) Chemical Co., Ltd.), diphenyl sulfone-3,3',4,4'-tetracarboxylic dianhydride (CAS: 2540-99-0), benzophenone-3,3',4,4'-tetracarboxylic dianhydride (CAS No.: 2421-28-5), 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride (custom compound, purchased from Alfaeza (China) Chemical Co., Ltd.), 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride (custom compound, purchased from Alfaeza (China) Chemical Co., Ltd.), 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride (custom compound, purchased from Alfaeza (China) Chemical Co., Ltd.), 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride (custom compound, purchased from Alfaeza (China) Chemical Co., Ltd.).

[0118] According to specific embodiments of the present invention, the amount of the alcohol compound with photosensitive groups added in the first mixing process 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 groups 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.

[0119] According to a specific embodiment of the present invention, the alcohol compound having a photosensitive group has the structure shown in formula (VI):

[0120]

[0121] Preferably, the alcohol compound having a photosensitive group is methyl methacrylate, ethyl methacrylate, hydroxypropyl methacrylate, etc.

[0122] 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.

[0123] (2) The esterification product is subjected to a second mixing treatment with diamine monomer a and diamine monomer b to obtain polyamic acid;

[0124] The diamine monomer a has the structure shown in formula (IV);

[0125] The diamine monomer b has the structure shown in formula (V);

[0126] H2N-Ar2-NH2 formula (IV); H2N-Ar4-NH2 formula (V).

[0127] Specifically, the following reaction occurs in this step:

[0128]

[0129] According to specific embodiments of the present invention, the molar ratio of diamine monomer a to diamine 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 diamine monomer a to diamine monomer b is (3:7)-(7:3), such as 3:7, 4:6, 5:5, 6:4, 7:3, etc.

[0130] According to specific embodiments of the present invention, the total amount of dianhydride monomer and the total amount of diamine monomer are preferably (1-1.05):1, for example 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, etc.

[0131] According to specific embodiments of the present invention, the diamine monomer a includes, but is not limited to, (Compound a-1, purchased from Alfaesa (China) Chemical Co., Ltd.) (Compound a-2, purchased from Alfaesa (China) Chemical Co., Ltd.) (Compound a-3, purchased from Alfaesa (China) Chemical Co., Ltd.) (Compound a-4, purchased from Alfaesa (China) Chemical Co., Ltd.)

[0132] 2-(4-aminophenyl)-5-aminopyridine (compound a-5, purchased from Alfaesa (China) Chemical Co., Ltd.).

[0133] According to specific embodiments of the present invention, the diamine monomer b includes, but is not limited to, diaminodiphenyl ether (CAS No.: 101-84-4), 3,4'-diaminodiphenylmethane (CAS No.: 19430-83-2), 4,4'-diaminodiphenylmethane (CAS No.: 101-77-9), 3,3'-diaminodiphenyl sulfone (CAS No.: 599-61-1), and 3,4'-diaminodiphenyl sulfone (purchased from Alfaesa (China) Chemical Co., Ltd.). 4,4'-Diaminodiphenyl sulfone (CAS No.: 80-08-0), 3,4'-Diaminodiphenyl sulfide (purchased from Alfa Aesa (China) Chemical Co., Ltd.), 1,4-bis(4-aminophenoxy)benzene (CAS No.: 3491-12-1), benzidine, 2,2'-bis(trifluoromethyl)benzene (CAS No.: 341-58-2), 3,3'-bis(trifluoromethyl)benzene 2,2'-Dimethylbenzidine (CAS No.: 346-88-3), 2,2'-Dimethylbenzidine (CAS No.: 96196-27-9, purchased from Alfaesa (China) Chemical Co., Ltd.), 3,3'-Dimethylbenzidine (CAS No.: 119-93-7), 3,3',5,5'-Tetramethylbenzidine (CAS No.: 54827-17-7), 2,2'-Dichlorobenzidine (CAS No.: 84-68-4), 3,3'-Dichlorobenzidine ( CAS No.: 91-94-1), 2,2',5,5'-tetrachlorobenzidine (CAS No.: 15721-02-5), m-phenylenediamine (CAS No.: 108-45-2), p-phenylenediamine (CAS No.: 106-50-3), 1,5-naphthylenediamine (CAS No.: 2243-62-1), 2,6-naphthylenediamine (CAS No.: 2243-67-6), bis(4-aminophenoxyphenyl) sulfone (purchased from Alfaesa (China) Chemical Co., Ltd.).

[0134] 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.

[0135] (3) The polyamic acid is subjected to an isomerization reaction to obtain an intermediate.

[0136] Specifically, the isoimide reaction includes reacting the polyamic acid with a basic catalyst and an isomerizing agent to obtain polyisoimide.

[0137] 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.

[0138] 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.

[0139] Specifically, the following reaction occurs in this step:

[0140]

[0141] 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.

[0142] 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.

[0143] 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.

[0144] (4) The intermediate is mixed with the alcohol compound having a photosensitive group in a third mixing process to obtain the polyimide precursor.

[0145] Specifically, the intermediate is mixed with an alcohol compound having a photosensitive group to achieve complete esterification, as shown in the following reaction:

[0146]

[0147] 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.

[0148] 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.

[0149] 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 precipitated substance, 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 washing solution may be deionized water or an alcohol, such as methanol, ethanol, isopropanol, etc.

[0150] 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.

[0151] A fourth aspect of the present invention provides a method for preparing a polyimide precursor solution, the method comprising:

[0152] The polyimide precursor is mixed with a photoinitiator to obtain the polyimide precursor solution;

[0153] 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.

[0154] 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).

[0155] 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%, for example 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, etc.

[0156] 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;

[0157] The polyimide film has the structure shown in formula (VII):

[0158]

[0159] The polyimide film is prepared from the aforementioned polyimide precursor solution and has a low coefficient of thermal expansion, low stress, high mechanical strength, and high thermal stability, making it suitable for chip manufacturing and packaging.

[0160] 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:

[0161] The polyimide precursor solution is coated onto the substrate surface, and then exposed and photocured to obtain the polyimide film.

[0162] 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.

[0163] 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.

[0164] Example 1

[0165] Preparation of polyimide precursors:

[0166] (1) Purge dry nitrogen gas into a 500 mL three-necked flask and add 40 mL of dry N-methylpyrrolidone, followed by 2.10 g of cyclopentanetetracarboxylic acid dianhydride and 3.10 g of 3,3',4,4'-oxophthalic acid 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.

[0167] (2) Subsequently, 1.85 g of 2-(4-aminophenyl)-5-aminopyridine and 2.12 g of 2,2'-dimethylbenzidine were dissolved in 30 mL of dry N-methylpyrrolidone in a dry beaker. The above diamine mixed solution was 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.

[0168] (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.

[0169] (4) Add 62g of hydroxyethyl methacrylate to the above solution and raise the temperature to 55℃, and react for 12h;

[0170] (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.

[0171] Preparation of photosensitive polyimide precursor solution:

[0172] 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.

[0173] The differences between the examples, comparative examples and Example 1 are shown in Table 1.

[0174] The photosensitivity test specifically includes:

[0175] 2.5 mL of polyimide precursor solution was dropped onto a 6-inch silicon wafer and coated by spin coating at 3000 rpm. The substrate was then baked on a hot plate at 90°C for 150 seconds to set the solution. Finally, the substrate was exposed to 300 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 (Olympus, model BX3M) and a scanning electron microscope (ZEISS, model GEMINI 500). The resolution of the material was defined as the smallest size in which the pattern remained intact and clear.

[0176] The coefficient of thermal expansion (CTE) test is specifically as follows:

[0177] 2.5 mL of polyimide precursor solution was dropped onto a 6-inch silicon wafer and spin-coated at 3000 rpm. The wafer was then baked on a hot plate at 90°C for 150 seconds to set the resin. The wafer was then cured in a nitrogen atmosphere at 350°C. The cured wafer was then immersed in a 1% HF solution until the PSPI film detached from the wafer. The CTE of the PSPI film was then tested on a TMA instrument (HITACHI, model TMA7100).

[0178] The thermal stability test specifically includes:

[0179] 2.5 mL of polyimide precursor solution was dropped onto a 6-inch silicon wafer and spin-coated at 3000 rpm. The solution was then baked on a hot plate at 90°C for 150 seconds to set the resin. The silicon wafer was then cured in a nitrogen atmosphere at 350°C. The cured silicon wafer was then immersed in a 1% HF solution until the PSPI film detached from the wafer. The PSPI film was cut into small pieces, and approximately 50 mg of the sample was placed in a thermogravimetric analyzer (METTLER TOLEDO, model TGA2) for thermal decomposition experiments. The initial decomposition temperature and the temperature at which 5% mass loss occurred were measured.

[0180] Table 1

[0181]

[0182]

[0183]

[0184]

[0185]

[0186]

[0187]

[0188] Continued from Table 1

[0189]

[0190]

[0191]

[0192]

[0193] The " / " indicates that it is not present.

[0194] The test results are shown in Table 2.

[0195] Table 2

[0196]

[0197]

[0198]

[0199] Analysis of experimental results:

[0200] As shown in Table 2, the photosensitive polyimide prepared by the method provided in this invention can achieve a balance of high resolution, low coefficient of thermal expansion, and thermal stability.

[0201] 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, 1:9, 2:3, and 3:2, 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 changed). The temperatures were 40℃, 25℃, and 45℃ respectively; Examples 10-11 differed from Example 1 only in the time of the first mixing treatment (the times of the first mixing treatment in Examples 1 and 8-9 were 2h, 1h, and 4h respectively); Examples 12-13 differed from Example 1 only in the molar ratio of diamine monomer a and diamine monomer b (the molar ratio of diamine monomer a and diamine monomer b in Examples 1 and 12-13 was 4:5, 3:7, and 7:3 respectively); Examples 14-16 differed from Example 1 only in the temperature of the second mixing treatment (the temperatures of the second mixing treatment in Examples 1 and 14-16 were 25℃, 0℃, 10℃, and 45℃ respectively). 5℃); Compared with Example 1, Examples 17-18 only changed the time of the second mixing treatment (the time of the second mixing treatment in Examples 1, 17-18 was 10h, 15h, and 20h, respectively); Compared with Example 1, Examples 19-20 only changed the mass ratio of alkaline catalyst to polyamic acid (the mass ratio of alkaline catalyst to polyamic acid in Examples 1, 19-20 was 2.12:100, 1:100, and 5:100, respectively), that is, the amount of alkaline catalyst added was changed; Compared with Example 1, Examples 21-22 only changed the mass ratio of isomerizing agent to polyamic acid (the mass ratio of isomerizing agent in Examples 1, 21-2 ... the amount of isomerizing agent added was changed. The mass ratios of the compounds to polyamic acid were 1.6:1, 1:1, and 3:1, respectively. Examples 23-24 differed from Example 1 only in the temperature of the isomerization reaction (25°C, 35°C, and 45°C in Examples 1 and 23-24, respectively). Examples 25-26 differed from Example 1 only in the time of the isomerization reaction (4h, 1h, and 6h in Examples 1 and 25-26, respectively). Examples 27-28 differed from Example 1 only in the mass ratio of the alcohol compound with the photosensitive group to the intermediate in the third mixing treatment (7% mass ratio in Examples 1 and 27-28, respectively).Examples 29-30 differ from Example 1 only in the temperature of the third mixing treatment (55°C, 35°C, and 45°C in Examples 1, 29-30, and 29-30, respectively); Examples 31-33 differ from Example 1 only in the time of the third mixing treatment (12h, 10h, 20h, and 24h in Examples 1, 31-33, and 24h, respectively); Examples 33-41 differ from Example 1 only in the type of dianhydride monomer a; Examples 42-54 differ only in the type of dianhydride monomer b; Examples 55-56 differ from the examples only in the type of alcohol compound with a photosensitive group; Examples 57-60 differ from Example 1 only in the type of diamine monomer a; Examples 61-82 differ only in the type of diamine monomer b; Examples 83-84 differ from Example 1 only in the type of basic catalyst; Example 85 differs only in the type of isomerizing agent.

[0202] All the above embodiments yielded photosensitive polyimide films that balance high resolution, low coefficient of thermal expansion, and thermal stability.

[0203] Compared with Example 1, Comparative Example 1 lacks aromatic dianhydride, resulting in a weaker molecular structure and a lower coefficient of thermal expansion, but also poorer thermal stability.

[0204] Compared with Example 1, Comparative Example 2 lacks aliphatic dianhydride, has a more rigid molecular structure, and although it has better thermal stability, its coefficient of thermal expansion is higher.

[0205] Compared with Example 1, Comparative Example 3 lacks diamines with pyridine or imidazole structures, resulting in poor molecular rigidity and a higher coefficient of thermal expansion.

[0206] Compared with Example 1, Comparative Example 4 lacks aromatic diamine, resulting in a weaker molecular structure. Although it has a lower coefficient of thermal expansion, its thermal stability is poor.

[0207] Compared with Example 1, Comparative Example 5 used aliphatic dianhydride and functional diamine, which have a lower coefficient of thermal expansion, but their molecular structure is softer and their thermal stability is poorer.

[0208] Compared with Example 1, Comparative Example 6 used aromatic dianhydrides and aromatic diamines, which have a more rigid molecular structure and better thermal stability, but their coefficient of thermal expansion is higher.

[0209] This invention introduces aliphatic dianhydrides and nitrogen heterocyclic structures, while retaining the aromatic ring structure in a blending manner, to obtain an ester-type photosensitive polyimide that has high resolution while also taking into account low coefficient of thermal expansion and thermal stability.

[0210] 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.

[0211] 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): Among them, m:n=x:y=(3:7)-(7:3); m:x=n:y=(1:9)-(3:2); Ar1 is an aliphatic group; Ar2 is an aromatic group containing a nitrogen heterocycle; Ar3 is the first aromatic group; Ar4 is the second 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, Ar4 includes At least one of them.

6. 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; Optionally, R1 can be either H or methyl. R2 is a C1-C3 divalent alkyl group.

7. A method for preparing the polyimide precursor according to any one of claims 1-6, characterized in that, include: The dianhydride monomers a and b are first mixed with an alcohol compound having a photosensitive group to obtain an esterified product. The esterification product is subjected to a second mixing treatment with diamine monomer a and diamine monomer b to obtain polyamic acid; The polyamic acid was subjected to an isomerization reaction to obtain an intermediate; 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 a has the structure shown in formula (IV); The diamine monomer b has the structure shown in formula (V); H2N-Ar2-NH2 formula (IV); H2N-Ar4-NH2 formula (V).

8. The method according to claim 7, characterized in that, The molar ratio of dianhydride monomer a to dianhydride monomer b is (1:9)-(3:2); Optionally, the ratio of the total molar amount of dianhydride monomer a and dianhydride monomer b to the molar amount of the alcohol compound having a photosensitive group in the first mixing process is 100:(5-50); Optionally, the alcohol compound having a photosensitive group has the structure shown in formula (VI): Optionally, the temperature of the first mixing treatment is 25-45°C; Optionally, the first mixing process takes 1-4 hours.

9. The method according to claim 7, characterized in that, The molar ratio of diamine monomer a to diamine monomer b is (3:7)-(7:3); Optionally, the ratio of the total molar amount of dianhydride monomer a and dianhydride monomer b to the total molar amount of diamine monomer a and diamine monomer b 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.

10. The method according to claim 7, 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.

11. The method according to claim 7, characterized in that, In the third mixing process, 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.

12. A polyimide precursor liquid, characterized in that, The polyimide precursor solution is obtained from the polyimide precursor according to any one of claims 1-6 or the polyimide precursor obtained by the method according to any one of claims 7-11.

13. 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 1-6 or the polyimide precursor obtained by the method according to any one of claims 7-11.

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

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