Alkali-soluble photosensitive polyimide as well as preparation method and application thereof

Abstract

The invention discloses alkali-soluble photosensitive polyimide as well as a preparation method and application thereof, and relates to the technical field of alkali-soluble photosensitive resin. The structure of the alkali-soluble photosensitive polyimide resin disclosed by the invention is as shown in the following formula (1): # imgabs0 #, wherein 1gt; x is greater than or equal to 0.3, n is an integer from 5 to 200, A1 is a residue of a dianhydride monomer, A2 is a residue of a diamine monomer with a hydroxyl group, and A3 is a residue of a diamine monomer without a hydroxyl group; wherein the structure of R is shown as a formula (2); in the # imgabs 1 #, B1 is a residue with an unsaturated double bond generated after the reaction of unsaturated anhydride and hydroxyl in A2, and m is an integer of 1-2. The alkali-soluble photosensitive polyimide provided by the embodiment of the invention can be cured at a low temperature of 250 DEG C or below, and has a relatively low curing temperature, and the cured material has a relatively high glass transition temperature and thermal decomposition temperature.

Description

Technical Field

[0001] The present application relates to the technical field of alkali-soluble photosensitive resins, and in particular to an alkali-soluble photosensitive polyimide and a preparation method and application thereof. Background Art

[0002] Currently, printed circuit boards (PCBs) are substrates for modern electrical installations and connecting components, and are important basic assembly parts in the electronics industry. When making circuit boards, often only a portion of the pads need to be soldered, so the pads and circuits that do not need to be soldered need to be protected with solder resist. Solder resist ink, as a protective coating covering the circuit, can prevent circuit corrosion and disconnection, prevent solder joints from shorting, regulate the amount of solder adhered, reduce copper dissolution contamination in the weld, and increase insulation. In addition, the coating also has excellent electrical insulation properties, corrosion resistance, moisture resistance, and mildew resistance, which can effectively prevent faults such as short circuits between circuits. The quality of this solder resist is related to the reliability and service life of the PCB.

[0003] With the advent of high-frequency communications, PCB substrates are gradually developing towards high density and refinement, and the performance requirements for solder mask coatings are becoming increasingly higher. Typically, PCB boards used for high-frequency and high-speed communications need to undergo a lead-tin soldering process above 260°C, which requires the photosensitive solder mask coating to have high heat resistance (high glass transition temperature and thermal decomposition temperature). Currently, the most widely used photosensitive solder mask inks are mainly based on acrylic modified epoxy resins. Although they have good light curing, developability, high adhesion and low curing shrinkage, they are prone to blistering or oil loss during soldering due to their low thermal stability, low glass transition temperature (generally below 160°C) and CTE mismatch with copper (generally above 30ppm / °C). They are prone to blistering or oil loss during soldering, and are prone to failure such as circuit cracking under wide temperature cycling conditions, which cannot meet the application requirements of electrical circuit boards.

[0004] In existing technologies, inorganic fillers such as silica are often added to improve the mechanical and thermal properties of photosensitive solder resist inks. However, the amount of inorganic fillers added is limited, resulting in limitations in improving the mechanical and thermal properties of this method. Furthermore, excessively high inorganic filler content can affect at least one of the ink's photolithographic performance, developing performance, leveling performance, and elongation at break, introducing a greater risk of interface failure. Related technologies disclose a positive photosensitive polyimide resin (e.g., CN111303420A). However, its molecular structure lacks photosensitive groups (e.g., carbon-carbon double bonds), resulting in a lack of photosensitivity and inability to undergo photocrosslinking reactions, which can easily lead to reduced photolithographic performance of the photosensitive solder resist composite.

[0005] Therefore, there is an urgent need to provide a photosensitive resin composition that has low curing temperature, good heat resistance, and good photolithography performance and development performance. Summary of the Invention

[0006] In view of this, the present application provides an alkali-soluble photosensitive polyimide and its preparation method and application, aiming to provide a photosensitive resin composition with low curing temperature, good heat resistance, and good photolithography performance and development performance.

[0007] In a first aspect, an embodiment of the present application provides an alkali-soluble photosensitive polyimide resin, the structure of which is shown in the following formula (1):

[0008]

[0009] wherein 1>x≥0.3, n is an integer from 5 to 200, A1 is the residue of a dianhydride monomer, A2 is the residue of a diamine monomer having a hydroxyl group, and A3 is the residue of a diamine monomer not having a hydroxyl group;

[0010] Wherein, the structure of R is shown in formula (2);

[0011]

[0012] Wherein B1 is a residue with an unsaturated double bond produced by the reaction of an unsaturated acid anhydride with the hydroxyl group in A2, and m is an integer of 1 to 2.

[0013] Beneficial effects:

[0014] The alkali-soluble photosensitive polyimide provided in the embodiment of the present application can be cured at a low temperature below 250°C, has a low curing temperature, and the cured material has a high glass transition temperature and thermal decomposition temperature. When the alkali-soluble photosensitive polyimide in the present application is used in a photosensitive solder resist composite (such as a photosensitive solder resist ink), it is beneficial to improve the heat resistance of the photosensitive solder resist composite having the alkali-soluble photosensitive polyimide. At the same time, since the structure of the alkali-soluble photosensitive polyimide in the present application contains a photosensitive group vinyl and a carboxyl functional group that can be developed in an alkaline aqueous solution, it can improve the heat resistance of the photosensitive solder resist composite while making the photosensitive solder resist composite have good photolithography performance and development performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 Schematic diagram of the reaction mechanism for preparing alkali-soluble photosensitive polyimide resin in the examples of the present application.

[0017] Figure 2 The alkali-soluble photosensitive polyimide resin prepared in the embodiment of the present application is 1 H NMR spectrum.

[0018] Figure 3 This is a partially enlarged view of a patterned photosensitive film prepared from the weakly alkali-soluble photosensitive resin composition prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0019] The experimental examples described in this application are only some of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain this application and are not intended to limit this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] In the description of this application, the term "including" means "including but not limited to." The terms first, second, third, etc. are used merely as labels and do not impose numerical requirements or establish a sequence.

[0022] In this application, "and / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0023] In this application, "at least one" means one or more, and "plurality" means two or more. "One or more", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or plural, respectively.

[0024] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0025] Printed circuit boards (PCBs) are the substrates used for modern electrical installations and component connections, and are essential basic assemblies in the electronics industry. When manufacturing circuit boards, soldering is often only necessary for a portion of the pads, so the pads and circuits not requiring soldering are protected with solder mask. Solder resist ink, a protective coating applied to the circuits, prevents corrosion and disconnection, prevents short circuits at solder joints, regulates solder adhesion, reduces copper dissolution contamination in the weld, and increases insulation. Furthermore, the coating offers excellent electrical insulation, corrosion resistance, moisture resistance, and mildew resistance, effectively preventing faults such as short circuits between circuits. The quality of this solder mask significantly impacts the reliability and service life of the PCB.

[0026] With the advent of high-frequency communications, PCB substrates are gradually developing towards high density and refinement, and the performance requirements for solder mask coatings are becoming increasingly higher. Typically, PCB boards used for high-frequency and high-speed communications need to undergo a lead-tin soldering process above 260°C, which requires the photosensitive solder mask coating to have high heat resistance (high glass transition temperature and thermal decomposition temperature). Currently, the most widely used photosensitive solder mask inks are mainly based on acrylic modified epoxy resins. Although they have good light curing, developability, high adhesion and low curing shrinkage, they are prone to blistering or oil loss during soldering due to their low thermal stability, low glass transition temperature (generally below 160°C) and CTE mismatch with copper (generally above 30ppm / °C). They are prone to blistering or oil loss during soldering, and are prone to failure such as circuit cracking under wide temperature cycling conditions, which cannot meet the application requirements of electrical circuit boards.

[0027] In existing technologies, inorganic fillers such as silica are often added to improve the mechanical and thermal properties of photosensitive solder mask inks. However, the amount of inorganic fillers added is limited, resulting in limitations in improving the mechanical and thermal properties of this method. Furthermore, excessively high inorganic filler content can affect at least one of the ink's photolithographic performance, developing performance, leveling performance, and elongation at break, introducing a greater risk of interface failure. Related technologies disclose a positive photosensitive polyimide resin (e.g., CN111303420A). However, its molecular structure lacks photosensitive groups (e.g., carbon-carbon double bonds) and lacks photosensitivity. This can lead to reduced photolithographic performance of the photosensitive solder mask ink when a photocrosslinking reaction occurs.

[0028] Therefore, there is an urgent need to provide a photosensitive resin composition that has low curing temperature, good heat resistance, and good photolithography performance and development performance.

[0029] In view of this, the first aspect of the present application provides an alkali-soluble photosensitive polyimide resin, the structure of which is shown in the following formula (1):

[0030]

[0031] wherein 1>x≥0.3, n is an integer from 5 to 200, A1 is the residue of a dianhydride monomer, A2 is the residue of a diamine monomer having a hydroxyl group, and A3 is the residue of a diamine monomer not having a hydroxyl group;

[0032] Wherein, the structure of R is shown in formula (2);

[0033]

[0034] Wherein, B1 is a residue with an unsaturated double bond produced by the reaction of an unsaturated acid anhydride with the hydroxyl group in A2, and m is an integer of 1 to 2.

[0035] The alkali-soluble photosensitive polyimide provided in the embodiment of the present application can be cured at a low temperature below 250°C, has a low curing temperature, and the cured material has a high glass transition temperature and thermal decomposition temperature. When the alkali-soluble photosensitive polyimide in the present application is used in a photosensitive solder resist composite (such as a photosensitive solder resist ink), it is beneficial to improve the heat resistance of the photosensitive solder resist composite having the alkali-soluble photosensitive polyimide. At the same time, since the structure of the alkali-soluble photosensitive polyimide in the present application contains a photosensitive group vinyl and a carboxyl functional group that can be developed in an alkaline aqueous solution, it can improve the heat resistance of the photosensitive solder resist composite while making the photosensitive solder resist composite have good photolithography performance and development performance.

[0036] It is understood that the specific structures of A1, A2, and A3 in the above formula (1) have a significant impact on the final performance of the product. When at least one of A1, A2, and A3 includes a biphenyl structure (i.e., the dianhydride monomer and / or diamine monomer used to prepare the alkali-soluble photosensitive polyimide resin in this application includes a monomer with a biphenyl structure), the prepared alkali-soluble photosensitive polyimide resin has a high glass transition temperature and a high thermal decomposition temperature. When A1, A2, and A3 contain a large number of flexible groups (e.g., ether bonds, ester groups, etc.), i.e., the dianhydride monomer and / or diamine monomer used to prepare the alkali-soluble photosensitive polyimide resin in this application includes a large number of flexible groups, it is beneficial to improve the toughness of the alkali-soluble photosensitive polyimide resin in this application. By controlling the reaction conditions (e.g., reaction temperature, reaction time, raw material ratio, etc.), the molecular weight of the alkali-soluble photosensitive polyimide resin in this application, i.e., the value of n in the above formula (1), can be adjusted.

[0037] In some embodiments of the present application, the molar fraction of the added amount of the hydroxyl-bearing diamine monomer to the total amount of the added hydroxyl-bearing diamine monomer and the non-hydroxyl-bearing diamine monomer is 30% to 100%. It should be noted that if the hydroxyl-bearing diamine monomer is less than 30%, the number of hydroxyl groups on the main chain of the molecule will be very small. The hydroxyl groups on the main chain of the molecule are reactive sites for unsaturated acid anhydrides. The reduction of reactive sites means that the grafting rate of the unsaturated acid anhydride is greatly reduced, thereby greatly reducing the content of photosensitive groups and alkali-soluble groups, and weakening the photosensitivity and alkali-solubility properties.

[0038] Illustratively, the diamine monomer for preparing the alkali-soluble photosensitive polyimide consists of a diamine monomer without a hydroxyl group and a diamine monomer with a hydroxyl group, and the added amount of the diamine monomer with a hydroxyl group accounts for 30% to 100% by mole of the total added amount of the diamine monomer with a hydroxyl group and the diamine monomer without a hydroxyl group.

[0039] In some embodiments of the present application, in the present application, a diamine without a hydroxyl group refers to a compound containing two amino groups in one molecule and no hydroxyl group.

[0040] Illustratively, the diamine monomer without a hydroxyl group is selected from one or more diamines such as nitrogen-containing heterocycles, siloxanes, and thioethers.

[0041] Furthermore, the diamine monomer without hydroxyl group is selected from 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, aminopropyl di-terminated polydimethylsiloxane, 3,5-diamino-1,2,4-triazole, 2,6-diaminopyridine, 2-(4-aminophenyl)-5-aminobenzimidazole, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 2-amino-4-[(3,4-diaminophenyl)sulfonyl]aniline, 6,6'-bisamino-3,3'-methylenedibenzoic acid, 1-hydrogen-indazole-4,7-diamine, 7-nitro-1H-indazole-4-amine, 2,2'-diamino-4,4'-bithiazole, 3,6-diaminocarbazole, 2-(3,6-diamino-9H-carbazole-9-yl)acetic acid methyl ester, 2,5-diaminobenzothiazole, 2,6-benzothiazole diamine, tert-butyl (6-amino-4-methylbenzo[D]thiazol-2-yl)carbamate, 4-methoxy-1,3-benzothiazole- 2,6-diamine, phenylguanamine, 2,4-diamino-6-(2-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-(4-chlorophenyl)-1,3,5-triazine, 2,4-diamino-6-[4-(trifluoromethyl)phenyl]-1,3,5-triazine, 2,4-diamino-6-(3-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine, 2,4-diamino-6-(4 -methylphenyl)-1,3,5-triazine, 2,4-diamino-6-(3,5-difluorophenyl)-1,3,5-triazine, 2,4-diamino-6-(4-bromophenyl)-1,3,5-triazine, 2,4-diamino-6-(4-methoxyphenyl)-1,3,5-triazine, 2,3-diaminophenolazine, methylguanamine, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine, 4,6-diaminopyrimidine, one or more thereof.

[0042] In the present application, the diamine monomer having a hydroxyl group refers to a compound containing two amino groups and one or more hydroxyl groups in one molecule.

[0043] Exemplarily, the diamine monomer with a hydroxyl group is selected from N-(2-hydroxyethyl)ethylenediamine, N-(2-hydroxyethyl)-1,3-propylenediamine, N,N'-bis(2-hydroxyethyl)ethylenediamine, N,N'-bis(2-hydroxyethyl)-1,3-propylenediamine, 4,6-diaminoresorcinol, 4,6-diaminoresorcinol dihydrochloride, bis(5-amino-2-hydroxyphenyl)methane hydrochloride, 3,3'-dihydroxybenzidine, 2,4-diamino-6-hydroxypyrimidine, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,4-diamino-6-hydroxymethylpteridine, 2,5-diamino-4,6-dihydroxypyrimidine hydrochloride, 2,5-diamino-1,4-dihydroxybenzene dihydrochloride, 3,3'-Dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3'-diamino-4,4'-dihydroxydiphenyl ether, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfide, 3,3'-diamino-4,4'-dihydroxybiphenyl, 3,3'-diamino-4,4'-dihydroxydiphenylmethane, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone, 5,5'-diamino-3,3,3',3'-tetramethyl-2,2',3,3'-tetrahydro-1,1'-spirobi[indene]-6,6'-diol, 4,4'-(9H-fluorene-9,9-diyl)bis(2-aminophenol), 9,9-dimethyl-9H-fluorene-2,7-diol.

[0044] Preferably, the diamine monomer with a hydroxyl group is selected from at least one of 2,5-diamino-4,6-dihydroxypyrimidine hydrochloride, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,5-diamino-1,4-dihydroxybenzene dihydrochloride, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,4-diamino-6-hydroxymethylpteridine, 4,6-diaminoresorcinol dihydrochloride, bis(5-amino-2-hydroxyphenyl)methane hydrochloride and 2,4-diamino-6-hydroxypyrimidine.

[0045] In some embodiments of the present application, the molar ratio of the total amount of diamine monomer (i.e., the sum of the molar amounts of diamine monomers with hydroxyl groups and diamine monomers without hydroxyl groups) to dianhydride is 1:1.4 to 2. Thus, the molar ratio of the total amount of diamine monomer to dianhydride is less than or equal to 1:1.4, which can avoid the molecular weight of the resulting alkali-soluble photosensitive polyimide resin being too large, which can easily lead to the alkali-soluble photosensitive polyimide resin in the present application being unable to develop a photolithographic pattern and being unable to be uniformly blended with other resins (such as epoxy resins). In addition, the molar ratio of the total amount of diamine monomer to anhydride is greater than or equal to 1:2, which avoids the problem of the final product having too low a molecular weight, resulting in unsatisfactory stability and heat resistance.

[0046] In some embodiments of the present application, the dianhydride monomer is selected from pyromellitic dianhydride, maleic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 4,4'-diphenylene dioxydiphthalic anhydride, One or more of dianhydrides such as phthalic anhydride, hexafluorodianhydride, 1,2-ethylenebis[1,3-dihydro-1,3-dioxoisobenzofuran-5-carboxylate], bisphenol A dianhydride, glycerol bis(dehydrated trimellitate) acetate, 2,3,3',4'-biphenyltetracarboxylic dianhydride, p-phenylene-bis(trimellitate) dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(acetylene-1,2-diyl) diphthalic anhydride, and 4,4'-oxydiphthalic anhydride.

[0047] In some embodiments of the present application, the dianhydride monomer is 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA for short); the diamine monomer without hydroxyl group is 4,4'-diaminodiphenyl ether (ODA for short); and the diamine monomer containing hydroxyl group is 3,3'-dihydroxybenzidine (HAB for short). Correspondingly, the reaction mechanism is shown in the attached figure. Figure 1 shown.

[0048] The second aspect of the present application further provides a method for preparing an alkali-soluble photosensitive polyimide resin, comprising the following steps:

[0049] In S100, a diamine monomer without a hydroxyl group, a diamine monomer with a hydroxyl group, and a dianhydride monomer are mixed under an inert atmosphere to obtain a pre-reaction liquid, and the pre-reaction liquid is reacted for a period of time to obtain a first reaction liquid containing polyamic acid.

[0050] Illustratively, a diamine monomer without a hydroxyl group is dissolved in a first solvent. After the diamine monomer without a hydroxyl group is completely dissolved, a diamine monomer with a hydroxyl group is added to the solution, stirred and dispersed for 1 to 3 hours, and then a dianhydride monomer is added and stirred for 12 to 24 hours to obtain a clear and viscous first reaction liquid.

[0051] In some embodiments of the present application, the inert atmosphere includes, but is not limited to, a nitrogen atmosphere, a helium atmosphere, a neon atmosphere, an argon atmosphere, a krypton atmosphere, a xenon atmosphere, and a radon atmosphere.

[0052] In some embodiments of the present application, the molar fraction of the added hydroxyl-bearing diamine monomer to the total added amount of the hydroxyl-bearing diamine monomer and the non-hydroxyl-bearing diamine monomer is 30% to 100%. It should be noted that if the hydroxyl-bearing diamine monomer is less than 30%, the hydroxyl groups on the main chain of the molecule will be very few. The hydroxyl groups on the main chain of the molecule are reactive sites for unsaturated acid anhydrides. The reduction of reactive sites means that the grafting rate of the unsaturated acid anhydride is greatly reduced, thereby greatly reducing the content of photosensitive groups and alkali-soluble groups, and weakening the photosensitivity and alkali-solubility properties.

[0053] In some embodiments of the present application, the molar ratio of the total amount of diamine monomer (i.e., the sum of the molar amounts of diamine monomers with hydroxyl groups and diamine monomers without hydroxyl groups) to the dianhydride monomer is 1:(1.4-2). Thus, the molar ratio of the total amount of diamine monomer to the anhydride is less than or equal to 1:1.4, which can avoid the molecular weight of the resulting alkali-soluble photosensitive polyimide resin being too large, which can easily lead to the alkali-soluble photosensitive polyimide resin in the present application being unable to develop a photolithographic pattern and being unable to be uniformly blended with other resins (such as epoxy resins). In addition, the molar ratio of the total amount of diamine monomer to the anhydride is greater than or equal to 1:2, which avoids the problem of the final product having too low a molecular weight, resulting in unsatisfactory stability and unsatisfactory heat resistance.

[0054] In some embodiments of the present application, the first solvent includes one or a combination of at least two of N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), toluene, xylene, methanol, ethanol, acetone, tetrahydrofuran, m-cresol, γ-butyrolactone, tetramethyl urea, dimethyl sulfoxide, hexamethylphosphoric acid triamide, and chloroform.

[0055] S110 adds a dehydrating agent to the first reaction liquid to dehydrate and cyclize the polyamic acid into polyimide, thereby obtaining a second reaction liquid containing polyimide.

[0056] For example, a dehydrating agent is slowly added dropwise to the first reaction solution to dehydrate and cyclize the polyamic acid to form polyimide. The reaction temperature for the dehydration and cyclization of the polyamic acid is 90° C. to 100° C., and the reaction time is 10 h to 24 h.

[0057] In some embodiments of the present application, the dehydrating agent is selected from at least one of an acid anhydride-tertiary amine dehydrating agent, a thionyl chloride-tertiary amine dehydrating agent, and an acetyl chloride-tertiary amine dehydrating agent. Furthermore, the acid anhydride is selected from at least one of acetic anhydride, phthalic anhydride, and trifluoroacetic anhydride; and the tertiary amine is selected from at least one of pyridine and triethylamine.

[0058] Furthermore, the dehydrating agent is selected from an acid anhydride-tertiary amine dehydrating agent, and the molar ratio of the acid anhydride to the tertiary amine is (1-1.2):1.

[0059] S120 adds an unsaturated second acid anhydride (i.e., an unsaturated acid anhydride) to the second reaction liquid, so that the hydroxyl groups in the molecular main chain of the polyimide react with the second acid anhydride, thereby introducing unsaturated double bonds and carboxyl groups into the molecular structure of the polyimide to obtain the alkali-soluble photosensitive polyimide resin.

[0060] Specifically, the hydroxyl groups in the main chain of the polyimide molecule obtained in step S110 react with the second acid anhydride to obtain a third reaction solution having unsaturated double bonds and carboxyl groups introduced into the polyimide molecular structure. The product in the third reaction solution is then precipitated to obtain an alkali-soluble photosensitive polyimide resin.

[0061] In some embodiments of the present application, the reaction temperature of step S120 is 80° C. to 100° C., and the reaction time is 10 h to 15 h.

[0062] For example, the second acid anhydride may be one or more of cis-4-cyclohexene-1,2-dicarboxylic anhydride, maleic anhydride, and 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexenyl-1,2-dicarboxylic anhydride.

[0063] In some embodiments of the present application, the amount of the second anhydride added is calculated based on the molar number of anhydride groups, and the molar ratio of the anhydride groups in the second anhydride to the hydroxyl groups in the hydroxyl-bearing diamine is (1-2):1. This allows the hydroxyl groups on the molecular chain to fully react with the unsaturated anhydride, thereby increasing the grafting rate.

[0064] Specifically, the third reaction liquid is placed in a precipitant having a volume 5 to 10 times that of the solvent, and repeatedly precipitated, filtered, washed, and dried to obtain an alkali-soluble photosensitive polyimide resin. It should be noted that the solvent volume here refers to the total volume of the solvent added during the entire reaction process.

[0065] Exemplarily, the precipitant is any one of methanol, ethanol, and acetone, or a combination of at least two thereof.

[0066] The third aspect of the present application further provides a weakly alkali-soluble photosensitive polyimide resin composition, comprising the aforementioned alkali-soluble photosensitive polyimide resin.

[0067] In some embodiments of the present application, the weak alkali-soluble photosensitive resin composition includes the above-mentioned alkali-soluble photosensitive polyimide resin, a photoinitiator, a photocrosslinker and a second solvent. Calculated by mass ratio, the alkali-soluble photosensitive polyimide resin: photoinitiator: photocrosslinker in the weak alkali-soluble photosensitive polyimide resin composition is 100: (3-7): (7-13). It should be noted that in the weak alkali-soluble photosensitive polyimide resin composition, the photocrosslinker and the alkali-soluble photosensitive polyimide resin can undergo a cross-linking reaction to form a cured product (e.g., a cured film). The photoinitiator can generate free radicals under light, thereby causing the photocrosslinker to undergo a photocross-linking reaction with the alkali-soluble photosensitive polyimide resin. The second solvent is used to adjust the viscosity of the weak alkali-soluble photosensitive polyimide resin composition.

[0068] In some embodiments of the present application, the photoinitiator can be selected from at least one of oxime ester photopolymerization initiators, acylphosphine oxide photopolymerization initiators, acetophenone photopolymerization initiators, benzoin and its alkyl ether photopolymerization initiators, anthraquinone photopolymerization initiators, thioxanthone photopolymerization initiators, ketal photopolymerization initiators and benzophenone photopolymerization initiators.

[0069] For example, the photoinitiator is an oxime ester photopolymerization initiator, such as OXE-1 and OXE-2; or an acylphosphine oxide photopolymerization initiator, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; or an acetophenone photopolymerization initiator, such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone and 1,1-dichloroacetophenone; or a benzoin and its alkyl ether photopolymerization initiator, such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isobutyl ether. Propyl ether; or, anthraquinone-based photopolymerization initiator, such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone and 1-chloroanthraquinone; or, a thioxanthone-based photopolymerization initiator, such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopropylthioxanthone; or, a ketal-based photopolymerization initiator, such as acetophenone dimethyl ketal and benzyl dimethyl ketal; or, a benzophenone-based photopolymerization initiator, such as one or more of benzophenone and 4,4'-bisdiethylaminobenzophenone.

[0070] In some embodiments of the present application, the photocrosslinking agent may be selected from at least one of hydroxyl-containing (meth)acrylates and monofunctional (meth)acrylates.

[0071] Illustratively, the photocrosslinking agent is a hydroxyl-containing (meth)acrylate, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate and dipentaerythritol penta(meth)acrylate; or, a monofunctional (meth)acrylate, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate and lauryl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, neopentyl glycol diethoxy / propoxy di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, polydipentaerythritol hexa(meth)acrylate or more.

[0072] In some embodiments of the present application, the second solvent is selected from one or more of N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP) or N,N-dimethylformamide (DMF), tetrahydrofuran, m-cresol, γ-butyrolactone, tetramethylurea, dimethyl sulfoxide, hexamethylphosphoric acid triamide and chloroform.

[0073] In some embodiments of the present application, the weakly alkali-soluble photosensitive polyimide resin composition comprises an alkali-soluble photosensitive polyimide resin, a photoinitiator, and a photocrosslinker as active ingredients. The weight ratio of alkali-soluble photosensitive polyimide resin: photoinitiator: photocrosslinker in the weakly alkali-soluble photosensitive polyimide resin composition is 100:(3-7):(7-13).

[0074] The fourth aspect of the present application further provides a photosensitive polyimide film, which includes the above-mentioned weakly alkali-soluble photosensitive polyimide resin composition.

[0075] In some embodiments of the present application, the photosensitive polyimide film is obtained by curing the aforementioned weakly alkali-soluble photosensitive polyimide composition. For example, the weakly alkali-soluble photosensitive polyimide composition is evenly spin-coated onto a glass sheet using a spin coater, then cured in a high-temperature oven using a stepwise heating process, and finally, removed by immersion in deionized water and dried.

[0076] In some embodiments of the present application, the thickness of the photosensitive polyimide film is 5 μm to 200 μm, more preferably 15 μm to 60 μm, and particularly preferably 20 μm to 50 μm.

[0077] A fifth aspect of the present application further provides a method for preparing a photosensitive polyimide film, comprising the following steps:

[0078] S200 provides a weak alkali-soluble photosensitive polyimide resin composition, which includes the above-mentioned alkali-soluble photosensitive polyimide resin, a photoinitiator, a photocrosslinking agent, and a second solvent.

[0079] It should be noted that the weakly alkali-soluble photosensitive polyimide resin composition has been described in detail above and will not be elaborated on here.

[0080] S210: coating the obtained weakly alkali-soluble photosensitive polyimide resin composition on a substrate to obtain a photosensitive film layer.

[0081] In some embodiments of the present application, the weakly alkali-soluble photosensitive polyimide resin composition is coated onto a carrier film using a coating device such as a reverse roll coater, gravure roll coater, notch wheel coater, curtain coater, or four-sided coater. A portion of the second solvent is then removed to obtain a photosensitive film layer. The photosensitive film layer is then cured and bonded to a protective film. The weakly alkali-soluble photosensitive polyimide resin composition can also be applied to a substrate via a spin coating process.

[0082] Illustratively, the substrate includes, but is not limited to, a glass sheet.

[0083] Illustratively, a weakly alkali-soluble photosensitive polyimide resin composition is coated on a carrier film to obtain a photosensitive coating, which is then placed on a hot plate at 80° C. to 120° C. and baked for 100 to 200 seconds to evaporate most of the solvent to form a photosensitive film layer.

[0084] S220 exposes, develops, and cures the obtained photosensitive film layer to obtain a patterned photosensitive polyimide film.

[0085] In some embodiments of the present application, the photosensitive film layer is exposed under i-line or g-line and developed with alkaline aqueous solution to obtain a photocured pattern with an exposure dose of 200 mJ / cm -2 ~2200mJ / cm -2 The developer is an alkaline aqueous solution such as sodium carbonate, and the developing time is 30s to 200s. The patterned photosensitive polyimide film is then placed in a high-temperature oven for post-curing to obtain a photosensitive polyimide pattern. The curing temperature is slightly higher than the boiling point of the solvent used.

[0086] In some embodiments of the present application, a weakly alkali-soluble photosensitive polyimide composition can be evenly spin-coated onto a glass sheet, then placed in a high-temperature oven in a nitrogen atmosphere, cured by step-by-step heating, and finally immersed in deionized water for demolding and drying to obtain a photosensitive polyimide cured film.

[0087] In some embodiments of the present application, the photosensitive polyimide cured film further includes a protective film covering the surface of the photosensitive polyimide cured film and a carrier film supporting the photosensitive polyimide cured film.

[0088] For example, the thickness of the carrier film and the protective film is preferably 5 μm-100 μm, more preferably 10 μm-30 μm. The types of the carrier film and the protective film include heat-resistant and solvent-resistant polymers such as polyethylene terephthalate, polypropylene, polyethylene, and polyester.

[0089] The sixth aspect of the present application further provides a weakly alkali-soluble photosensitive resin composition. Calculated by mass, the effective ingredients of the weakly alkali-soluble photosensitive resin composition include:

[0090] 100 parts of alkali-soluble multifunctional photosensitive epoxy resin;

[0091] 10 to 60 parts of the above-mentioned alkali-soluble photosensitive polyimide resin;

[0092] 1 to 40 parts of a photopolymerization initiator;

[0093] 5 to 50 parts of photopolymerizable monomer;

[0094] 10 to 80 parts of heat-curing component;

[0095] and 10 to 100 parts of filler.

[0096] The weakly alkali-soluble photosensitive resin composition prepared in this example has high heat resistance, good photolithographic and developing properties, and can be used as a photosensitive solder mask ink. It should be noted that the alkali-soluble multifunctional photosensitive epoxy resin in this application refers to a multifunctional epoxy resin containing photosensitive groups and alkali-soluble groups in its molecular chain. Multifunctional refers to a resin containing three or more epoxy groups.

[0097] Furthermore, the photosensitive groups contained in the epoxy resin molecular chain may be at least one of a carbonyl group, a carboxyl group, a peroxide group, and a carbon-carbon double bond. The alkali-soluble groups contained in the epoxy resin molecular chain may be at least one of a carboxyl group, an acid anhydride group, and an ester group.

[0098] In some embodiments of the present application, the acid value of the alkali-soluble multifunctional photosensitive epoxy resin is 40 mg KOH / g to 200 mg KOH / g, and more preferably 50 mg KOH / g to 180 mg KOH / g.

[0099] In some embodiments of the present application, the number average molecular weight of the alkali-soluble multifunctional photosensitive epoxy resin is 2,000 to 100,000, and more preferably 5,000 to 30,000.

[0100] In some embodiments of the present application, the ratio of the alkali-soluble photosensitive polyimide resin to the sum of the mass of the alkali-soluble photosensitive polyimide resin and the alkali-soluble multifunctional photosensitive epoxy resin in the weakly alkali-soluble photosensitive resin composition is 10% to 30%. It should be noted that if the mass ratio of the alkali-soluble photosensitive polyimide resin to the alkali-soluble multifunctional photosensitive epoxy resin in the weakly alkali-soluble photosensitive resin composition is greater than 30%, phase separation of the alkali-soluble photosensitive polyimide resin and the alkali-soluble multifunctional photosensitive epoxy resin may occur.

[0101] In some embodiments of the present application, the alkali-soluble multifunctional photosensitive epoxy resin is selected from photosensitive epoxy resins with two or more functional groups, specifically phenol novolac epoxy resin, bisphenol A novolac epoxy resin, naphthalene epoxy resin, o-cresol novolac epoxy resin, alkylphenol novolac epoxy resin, dicyclopentadiene epoxy resin, glycidylamine epoxy resin, trihydroxybenzene methane epoxy resin, tetraphenol ethane epoxy resin, diglycidyl phthalate resin and at least one epoxy compound of a condensation product of phenols and an aromatic aldehyde having a phenolic hydroxyl group.

[0102] In some embodiments of the present application, the type of photopolymerization initiator is not particularly limited, and specific examples include photopolymerization initiator 907; oxime ester photopolymerization initiators, such as OXE-1 and OXE-2; or acylphosphine oxide photopolymerization initiators, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; or acetophenone photopolymerization initiators, such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone and 1,1-dichloroacetophenone; or benzoin and its alkyl ether photopolymerization initiators, such as benzoin, benzophenone, Azoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether; or, anthraquinone-based photopolymerization initiator, such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone and 1-chloroanthraquinone; or, a thioxanthone-based photopolymerization initiator, such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopropylthioxanthone; or, a ketal-based photopolymerization initiator, such as acetophenone dimethyl ketal and benzyl dimethyl ketal; or, a benzophenone-based photopolymerization initiator, such as one or more of benzophenone and 4,4'-bisdiethylaminobenzophenone.

[0103] In some embodiments of the present application, the photopolymerizable monomer is selected from at least one of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, neopentyl glycol diethoxy / propoxy di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and polydipentaerythritol hexa(meth)acrylate.

[0104] In some embodiments of the present application, the heat-curing component is an epoxy resin. Exemplarily, the heat-curing component is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, brominated bisphenol A epoxy resin, bixylenol epoxy resin, biphenol epoxy resin, alicyclic epoxy resin, novolac epoxy resin, cresol-soluble epoxy resin, trisphenol methane epoxy resin, N-glycidyl epoxy resin, triglycidyl isocyanurate, 2,6-xylenol dimer diglycidyl ether, alicyclic epoxy resin, and xylene epoxy resin.

[0105] In some embodiments of the present application, the filler is an inorganic filler, and the inorganic filler is selected from at least one of barium sulfate, barium titanate, calcium oxide, talc, fumed silica, silica, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, titanium oxide, mica powder and kaolin, preferably at least one of barium sulfate, silica, aluminum oxide, aluminum hydroxide and calcium carbonate.

[0106] In some embodiments of the present application, the particle size of the inorganic filler is 0.001 μm to 100 μm, preferably 0.05 μm to 20 μm, and more preferably 0.05 μm to 3 μm. In particular, when the weakly alkali-soluble photosensitive resin composition requires further grinding, the particle size of the inorganic filler may also be in other ranges without particular limitation.

[0107] In some embodiments of the present application, the preparation method of the alkali-soluble multifunctional photosensitive epoxy resin comprises the following steps:

[0108] S300 is to carry out esterification reaction between a multifunctional epoxy compound and an unsaturated monocarboxylic acid, and then obtain an esterified product.

[0109] It should be noted that the multifunctional epoxy resin has been described in detail above and is not limited here. The specific conditions of the esterification reaction do not belong to the main improvement points of this application and are not described here.

[0110] Illustratively, the unsaturated monocarboxylic acid can be acrylic acid, acrylic acid dimer, methacrylic acid, β-styryl acrylic acid, β-furfuryl acrylic acid, crotonic acid, α-cyanocinnamic acid, cinnamic acid, the reaction product of a saturated / unsaturated dibasic acid anhydride and a hydroxyl-containing (meth)acrylate, and the reaction product of a saturated / unsaturated dibasic acid and an unsaturated monoglycidyl compound, etc. The above-mentioned can be used alone or in any combination.

[0111] In step S310 , the esterified product obtained in step S300 is reacted with a saturated / unsaturated polyacid anhydride to obtain an alkali-soluble multifunctional photosensitive epoxy resin.

[0112] In some embodiments of the present application, the saturated / unsaturated polybasic acid anhydride may be a dibasic acid anhydride, a polybasic acid anhydride, or a derivative of a corresponding acid anhydride.

[0113] The saturated / unsaturated polyacid anhydride can be a dibasic acid anhydride, such as maleic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride; or a polybasic aromatic carboxylic acid anhydride, such as trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride; or other acid anhydride derivatives, such as at least one of 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexenyl-1,2-dicarboxylic anhydride. Preferably, the saturated / unsaturated polyacid anhydride is tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and succinic anhydride. This helps further improve the photolithographic performance of the weakly alkali-soluble photosensitive resin composition.

[0114] In some embodiments of the present application, the weight ratio of the multifunctional epoxy compound: unsaturated monocarboxylic acid: saturated / unsaturated polyanhydride is (2.5-4): (0.5-1.1): (0.5-1.1). This helps to increase the crosslink density of the weakly alkali-soluble photosensitive resin composition after curing, resulting in a higher Tg (i.e., glass transition temperature) of the cured product.

[0115] In some embodiments of the present application, the weakly alkali-soluble photosensitive resin composition further comprises a third solvent, and the type of the third solvent is not particularly limited. For example, the third solvent may specifically include ethers, such as ethylene glycol monomethyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, etc.; esters, such as ethyl acetate, butyl acetate, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, etc. Ethyl ether acetate, diethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate, dipropylene glycol butyl ether acetate, etc.; ketones, such as butanone, cyclohexanone, isophorone; aromatic solvents, such as toluene, xylene, tetramethylbenzene; and petroleum solvents, such as naphtha, oxidized naphtha, solvent naphtha, etc. The above-mentioned solvents can be used alone or in any combination.

[0116] In some embodiments of the present application, the weakly alkali-soluble photosensitive resin composition further comprises a pigment. For example, the pigment is selected from at least one of phthalocyanine green, phthalocyanine blue, titanium dioxide, carbon black, and lithopone, and is preferably a pigment free of free halogen.

[0117] In some embodiments of the present application, the weakly alkali-soluble photosensitive resin composition further includes an additive; the additive is selected from at least one of an epoxy resin curing accelerator, a photoinitiator aid, a thixotropic tackifier, a diluent, an inhibitor, a tackifier, a defoaming agent, a leveling agent, a coupling agent, an antioxidant, and a rust inhibitor; in certain specific embodiments, the weight portion of the additive is 0.05 to 20 parts.

[0118] In a seventh aspect, the present application further provides a photosensitive dry film, which is obtained by curing the above-mentioned weakly alkali-soluble photosensitive resin composition.

[0119] For example, the weakly alkali-soluble photosensitive resin composition is coated on the carrier film using a coating device such as a reverse roll coater, a gravure roll coater, a notch wheel coater, a curtain coater, or a four-sided coater, and then the protective film is attached after curing.

[0120] In some embodiments of the present application, the thickness of the photosensitive dry film is 5 μm to 200 μm, more preferably 15 μm to 60 μm, and particularly preferably 20 μm to 50 μm.

[0121] In some embodiments of the present application, curing is performed under heating conditions. Further, the heating temperature is 150°C to 120°C, more preferably 160°C to 180°C, and the heating time is 30 minutes to 120 minutes, more preferably 50 minutes to 80 minutes.

[0122] In some embodiments of the present application, the photosensitive dry film further includes a protective film covering the surface of the photosensitive dry film and a carrier film supporting the photosensitive dry film. The thickness of the carrier film and the protective film is preferably 5-100 μm, more preferably 10-30 μm. Examples of the carrier film and the protective film include heat-resistant and solvent-resistant polymers such as polyethylene terephthalate, polypropylene, polyethylene, and polyester.

[0123] In an eighth aspect, the present application further provides a method for preparing a weakly alkali-soluble photosensitive resin composition, comprising the following steps:

[0124] S400 dissolves the alkali-soluble photosensitive polyimide resin in a solvent to prepare a glue solution.

[0125] It should be noted that the alkali-soluble photosensitive polyimide resin and the solvent have been described in detail above and will not be described in detail here.

[0126] In step S410 , the remaining components are added to the glue solution obtained in step S400 , and after mixing, a weakly alkali-soluble photosensitive resin composition is obtained.

[0127] For example, the mixing process includes a first mixing process and a second mixing process, wherein the stirring speed in the first mixing process is 500 rpm to 15000 rpm and the stirring time is 2 hours to 10 hours. The second mixing process is to re-mix the product after the first mixing process using a three-roll mill.

[0128] It should be noted that the weakly alkali-soluble photosensitive resin composition in the present application can be used for semiconductor packaging, preparation of photosensitive solder resist ink, preparation of circuit boards, preparation of FC-BGA substrates, etc.

[0129] Example 1 of Weakly Alkali-Soluble Photosensitive Polyimide Resin Composition

[0130] (1) Preparation of alkali-soluble photosensitive polyimide resin 1

[0131] Under a nitrogen atmosphere, 2.4519 g of 4,4'-diaminodiphenyl ether (ODA) was dissolved in 250 ml of DMAc. After the ODA was completely dissolved, 2.6211 g of 3,3'-dihydroxybenzidine (HAB) was added to the solution, stirred and dispersed for 1 hour, and then 12.915 g of 4,4'-oxydiphthalic anhydride (ODPA) was added and stirred for 24 hours to obtain a clear viscous solution. Then, a mixture of pyridine and acetic anhydride was slowly added dropwise to the reaction flask, and the reaction was continued at 100°C for 15 hours. After the reaction was completed, 3.7261 g of cis-4-cyclohexene-1,2-dicarboxylic anhydride (THPA) was added to the solution and the reaction was continued for 10 hours. After the reaction was completed, the resulting product was placed in 2.5 L of ethanol and repeatedly precipitated, filtered, washed, and dried to obtain a low-temperature curing weak alkali-soluble photosensitive polyimide 1. 1HNMR Ptule Figure 2 As shown. Figure 2 It can be seen that 1 In the H NMR spectrum, 7ppm-8ppm is the peak on the benzene ring, and 5.5ppm-5.85ppm is the peak on the hydrogen atoms on the unsaturated double bonds on the side chains of the photosensitive polyimide. The appearance of the corresponding hydrogen atoms indicates the successful synthesis of the product.

[0132] (2) Preparation of weakly alkali-soluble photosensitive polyimide resin composition

[0133] The prepared alkali-soluble photosensitive polyimide resin 1 was dissolved in dimethylacetamide and a photoinitiator (2.1 g of photopolymerization initiator 907), a photocrosslinker (3 g of polydipentaerythritol hexaacrylate) and a solvent (diethylene glycol ethyl ether acetate) were added to prepare a weak alkali-soluble photosensitive polyimide composition with a solid content of 30%.

[0134] The weakly alkali-soluble photosensitive polyimide composition was evenly spin-coated onto a glass sheet using a coating apparatus, and then placed in a high-temperature oxygen-free nitrogen oven for step-by-step thermal curing (100°C for one hour, 200°C for one hour, and 250°C for one hour). Finally, the film was immersed in deionized water for 24 hours for demolding, dried to obtain a photosensitive polyimide film, and finally laser cut to obtain strips.

[0135] The Tg of cured films of PSPI (weakly alkali-soluble photosensitive polyimide resin composition Example 1) was measured using a dynamic thermomechanical analyzer (DMA). PSPI film samples were cut into 15 mm × 5 mm wide rectangular strips, and the thickness of each strip was measured at five different locations, with the average thickness taken as the strip thickness. The test parameters were set as follows: gauge length 10 mm, heating rate 5°C / min, test temperature range from room temperature to 450°C for PSPI samples, and room temperature to 250°C for SR samples. During the test, the storage modulus and dissipation factor curves as a function of temperature were recorded in real time. The Tg value was determined by analyzing the peak position of the dissipation factor curve.

[0136] The mechanical properties of the prepared PSPI-cured films were tested using a dynamic thermomechanical analyzer (DMA). Before testing, all film samples were cut into 15 mm × 5 mm wide rectangular splines. The thickness of each spline was measured at five different locations, and the average of the measured values was used as the spline thickness. During testing, the gauge length was set to 10 mm. The spline was secured in a DMA fixture, and the thickness was entered into a computer. The tensile rate was set to 1 N / min, and the test temperature was room temperature. From the initial stretching of the spline to its fracture, the instrument generated a stress-strain curve, from which three mechanical property parameters were derived: Young's modulus, elongation at break, and fracture strength. Because the results are significantly affected by defects in the spline itself, five sets of valid data were obtained for each specimen, excluding any significant abnormalities, and the average of these values was used as the final result.

[0137] The thermal stability of PSPI-cured films was characterized using a thermogravimetric analyzer. All film samples were dried in a vacuum oven at 100°C for at least 5 hours before testing to eliminate moisture interference. The test conditions were as follows: approximately 10 mg of sample was placed in an alumina crucible and heated from room temperature to 800°C at a heating rate of 10°C / min under a nitrogen atmosphere. By analyzing the TGA curve, the 5% thermal weight loss temperature (T) was extracted. 5％ .

[0138] Focused ion beam microscopy was used to observe the profile and cross-sectional morphology of the photolithographic pattern. The cut copper plate was first secured to the sample stage with conductive adhesive and then gold-sputtered in an ion sputtering instrument with a current of 20 mA for 60 seconds to enhance the sample's conductivity. During characterization, the target pattern area was first identified at low magnification. A gallium ion beam was then used to cut the selected area, exposing the cross-sectional structure of the pattern. High-resolution surface and cross-sectional morphology images were acquired using a secondary electron detector, allowing analysis of key morphological parameters such as sidewall angle and edge roughness.

[0139] The above test results are shown in Table 1.

[0140]

[0141] As can be seen from Table 1, the alkali-soluble photosensitive polyimide resin prepared in the examples of the present application can be used for photolithography and development when used in a weakly alkali-soluble photosensitive polyimide resin composition, can be cured at a low temperature below 250°C, and has a low curing temperature. At the same time, the obtained cured film has a high glass transition temperature, thermal decomposition temperature, and good mechanical properties.

[0142] Example 1 of Weakly Alkali-Soluble Photosensitive Resin Composition

[0143] (1) Preparation of alkali-soluble photosensitive polyimide resin 1

[0144] Under a nitrogen atmosphere, 2.4519 g of 4,4'-diaminodiphenyl ether (ODA) was dissolved in 250 ml of DMAc. After the ODA was completely dissolved, 2.6211 g of 3,3'-dihydroxybenzidine (HAB) was added to the solution, stirred and dispersed for 1 hour, and then 12.915 g of 4,4'-oxydiphthalic anhydride (ODPA) was added and stirred for 24 hours to obtain a clear viscous solution. Then, a mixture of pyridine and acetic anhydride was slowly added dropwise to the reaction flask, and the reaction was continued at 100°C for 15 hours. After the reaction was completed, 3.7261 g of cis-4-cyclohexene-1,2-dicarboxylic anhydride (THPA) was added to the solution and the reaction was continued for 10 hours. After the reaction was completed, the resulting product was placed in 2.5 L of ethanol and repeatedly precipitated, filtered, washed, and dried to obtain a low-temperature curing weak alkali-soluble photosensitive polyimide 1. 1 HNMR Ptule Figure 2 As shown. Figure 2 It can be seen that 1 In the H NMR spectrum, 7-8 ppm is the peak on the benzene ring, and 5.5-5.85 ppm is the peak on the hydrogen atoms on the unsaturated double bonds on the side chains of the photosensitive polyimide. The appearance of the corresponding hydrogen atoms indicates the successful synthesis of the product.

[0145] (2) Preparation of alkali-soluble multifunctional photosensitive resin

[0146] 210 g of o-cresol-formaldehyde epoxy resin (epoxy equivalent weight 210), 0.5 g of hydroquinone, and 195 g of diethylene glycol ethyl ether acetate were added to a four-necked round-bottom flask under a nitrogen atmosphere, stirred, and heated to 105° C., where the temperature was maintained for 1 hour to dissolve all the substances. After complete dissolution, the flask was cooled to 90° C., followed by the dropwise addition of 72 g of acrylic acid and 1 g of triphenylphosphine, the temperature being maintained at 95° C. During the addition, the temperature was raised to 105° C., and the reaction was continued at this temperature for 12 hours. During the reaction, the acid value of the reactants was measured until the acid value reached 0.8 mg KOH / g, the temperature was then reduced to 60° C., and 75 g of tetrahydrophthalic anhydride was added, followed by the reaction at 90° C. for 4 to 8 hours. Finally, a light yellow alkali-soluble multifunctional photosensitive resin 1 having a solid content of 65% and a solid acid value of 95.2 mg KOH / g was obtained.

[0147] (3) Preparation of weakly alkali-soluble photosensitive resin composition

[0148] The photosensitive polyimide resin 1 and the alkali-soluble multifunctional photosensitive resin 1 were dissolved in diethylene glycol ethyl ether acetate according to a solid content of 65%, mechanically stirred for 2 hours, and filtered to obtain a photosensitive polyimide resin glue and a photosensitive epoxy resin glue; 1.539g of the photosensitive polyimide resin glue was added with 0.01g of a low-temperature curing accelerator 4-chloroquinoline, and stirred at room temperature for 2 hours; 29.231g of the photosensitive epoxy resin glue (the alkali-soluble photosensitive polyimide resin 1 accounts for 1% of the alkali-soluble photosensitive polyimide resin 1 and the alkali-soluble multifunctional photosensitive resin 1) was added to the 1.539g photosensitive polyimide resin glue. 5% of the total mass of resin 1), 2.1g of photopolymerization initiator 907, 3g of polydipentaerythritol hexaacrylate, 8g of heat-curing epoxy resin YX4000, 5g of silicon dioxide (particle size of 100nm to 3μm), 10g of barium sulfate (particle size of 50nm to 3μm), 0.8g of phthalocyanine green, 0.4g of melamine, 0.9g of dicyandiamide, and 20g of diethylene glycol ethyl ether acetate were stirred at 800rpm for 2h under mechanical stirring; after mixing evenly, they were mixed again on a three-roll mill to prepare a weakly alkali-soluble photosensitive resin composition 1.

[0149] The weakly alkali-soluble photosensitive resin composition 1 was coated on a carrier film using a four-sided coater, pre-baked at 75°C, exposed to UV light, developed with a weak base, and cured at 170°C to obtain a sample strip. Figure 3 It can be seen that the photosensitive solder resist ink containing photosensitive polyimide added to the weakly alkaline soluble photosensitive resin composition 1 can still produce micropores of 40 μm, with clean interiors, sharp and clear edges, and good photolithography performance.

[0150] Example 2 of Weakly Alkali-Soluble Photosensitive Resin Composition

[0151] The difference from embodiment 1 is that when preparing the photosensitive resin composition, the amount of the alkali-soluble photosensitive polyimide resin 1 is increased, specifically, the alkali-soluble photosensitive polyimide resin 1 in the photosensitive resin composition accounts for 10% of the total mass of the alkali-soluble photosensitive polyimide resin 1 and the alkali-soluble multifunctional photosensitive resin 1.

[0152] Example 3 of Weakly Alkali-Soluble Photosensitive Resin Composition

[0153] The difference from Example 1 is that when preparing the photosensitive resin composition, the amount of the alkali-soluble photosensitive polyimide resin 1 is increased, specifically, the alkali-soluble photosensitive polyimide resin 1 in the photosensitive resin composition accounts for 15% of the total mass of the alkali-soluble photosensitive polyimide resin 1 and the alkali-soluble multifunctional photosensitive resin 1.

[0154] Example 4 of Weakly Alkali-Soluble Photosensitive Resin Composition

[0155] The difference from Example 1 is that when preparing the photosensitive resin composition, the amount of the alkali-soluble photosensitive polyimide resin 1 is increased, specifically, the alkali-soluble photosensitive polyimide resin 1 in the photosensitive resin composition accounts for 20% of the total mass of the alkali-soluble photosensitive polyimide resin 1 and the alkali-soluble multifunctional photosensitive resin 1.

[0156] Weakly alkali-soluble photosensitive resin composition Example 5

[0157] The difference from Example 1 is that when preparing the photosensitive resin composition, the amount of the alkali-soluble photosensitive polyimide resin 1 is increased, specifically, the alkali-soluble photosensitive polyimide resin 1 in the photosensitive resin composition accounts for 25% of the total mass of the alkali-soluble photosensitive polyimide resin 1 and the alkali-soluble multifunctional photosensitive resin 1.

[0158] Weakly Alkali-Soluble Photosensitive Resin Composition Example 6

[0159] The difference from embodiment 1 is that when preparing the photosensitive resin composition, the amount of the alkali-soluble photosensitive polyimide resin 1 is increased, specifically, the alkali-soluble photosensitive polyimide resin 1 in the photosensitive resin composition accounts for 30% of the total mass of the alkali-soluble photosensitive polyimide resin 1 and the alkali-soluble multifunctional photosensitive resin 1.

[0160] Comparative Example 1 of Weakly Alkali-Soluble Photosensitive Resin Composition

[0161] The difference from Example 1 is that: the photosensitive resin composition is prepared, specifically, the alkali-soluble photosensitive polyimide resin 1 is not added into the photosensitive resin composition.

[0162] The Tg values of the films prepared in Examples 1-6 and Comparative Example 1 were measured using a dynamic thermomechanical analyzer (DMA). All SR film samples were cut into 15 mm x 5 mm wide rectangular strips. The thickness of each strip was measured at five different locations, and the average thickness was taken as the strip thickness. The test parameters were set as follows: gauge length 10 mm, heating rate 5°C / min, and sample temperature from room temperature to 250°C. During the test, the storage modulus and dissipation factor curves as a function of temperature were recorded in real time. The Tg value was determined by analyzing the peak position of the dissipation factor curve.

[0163] The thermal stability of the films prepared in Examples 1-6 and Comparative Example 1 was characterized using a thermogravimetric analyzer. All film samples were dried in a vacuum oven at 100°C for at least 5 hours before testing to eliminate moisture interference. The test conditions were as follows: approximately 10 mg of sample was placed in an alumina crucible and heated from room temperature to 800°C at a rate of 10°C / min under a nitrogen atmosphere. The 5% thermal weight loss temperature (T5%) was determined by analyzing the TGA curves.

[0164] The dynamic thermomechanical analyzer (DMA) was used to test the mechanical properties of the films prepared in Examples 1-6 and Comparative Example 1. Before the test, all film samples were cut into 15mm×5mm wide rectangular splines, and the thickness of each spline was measured at five different positions, and the average value was taken as the spline thickness. During the test, the gauge length was set to 10mm, and the thickness of the spline was input on the computer after the spline was fixed in the DMA fixture. The stretching rate was set to 1N / min, and the test temperature was room temperature. During the process from the beginning of stretching to the breaking of the spline, the instrument generated a stress-strain curve, from which three mechanical property parameters can be obtained: Young's modulus, elongation at break, and breaking strength. Since the results are greatly affected by the defects of the spline itself, each sample needs to obtain 5 sets of valid data after excluding obvious abnormal data and take the average value as the final result.

[0165] To further analyze the microscopic morphology of photolithographic patterns, this study used focused ion beam microscopy to observe the outline and cross-sectional morphology of the patterns. A cut copper plate was first secured to a sample stage with conductive adhesive. The sample was then gold-sputtered in an ion sputtering instrument with a current of 20 mA for 60 seconds to enhance conductivity. During characterization, the target pattern area was first identified at low magnification. A gallium ion beam was then used to section the selected area, exposing the cross-sectional structure of the pattern. High-resolution surface and cross-sectional morphology images were acquired using a secondary electron detector, allowing analysis of key morphological parameters such as sidewall angle and edge roughness.

[0166] The test results of Examples 1 to 6 and Comparative Example 1 are shown in Table 2.

[0167] Table 2

[0168]

[0169] The difference between Examples 1 to 6 and Comparative Example 1 is whether the alkali-soluble photosensitive polyimide resin with the structure represented by formula (1) is added to the weakly alkali-soluble photosensitive resin composition. As can be seen from Table 1, the addition of the alkali-soluble photosensitive polyimide resin with the structure represented by formula (1) to the weakly alkali-soluble photosensitive resin composition can significantly improve the glass transition temperature, thermal stability and elongation at break of the material after the weakly alkali-soluble photosensitive resin composition is cured without substantially affecting its photolithography performance and development performance.

[0170] The difference between Examples 1 to 6 lies in the different mass ratios of the alkali-soluble photosensitive polyimide resin to the alkali-soluble multifunctional photosensitive epoxy resin in the weakly alkali-soluble photosensitive resin composition. As can be seen from Table 1, increasing the mass ratio of the alkali-soluble photosensitive polyimide resin in the weakly alkali-soluble photosensitive resin composition further improves the glass transition temperature and thermal decomposition temperature of the cured product. However, when the mass ratio of the alkali-soluble photosensitive polyimide resin to the alkali-soluble multifunctional photosensitive epoxy resin in the weakly alkali-soluble photosensitive resin composition is greater than 25%, the photolithographic performance of the weakly alkali-soluble photosensitive resin composition decreases to a certain extent. When the mass ratio of the alkali-soluble photosensitive polyimide resin in the weakly alkali-soluble photosensitive resin composition is between 5% and 25%, the resulting weakly alkali-soluble photosensitive resin composition has both good photolithographic and developing properties, and the cured product also has a high glass transition temperature, thermal stability, and mechanical properties.

[0171] The above is a detailed introduction to the technical solutions provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An alkali-soluble photosensitive polyimide resin, characterized in that: The structure of the alkali-soluble photosensitive polyimide resin is shown in the following formula (1): wherein 1>x≥0.3, n is an integer from 5 to 200, A1 is the residue of a dianhydride monomer, A2 is the residue of a diamine monomer having a hydroxyl group, and A3 is the residue of a diamine monomer not having a hydroxyl group; Wherein, the structure of R is shown in formula (2); Wherein, B1 is a residue with an unsaturated double bond produced by the reaction of an unsaturated acid anhydride with the hydroxyl group in A2, and m is an integer of 1 to 2.

2. The alkali-soluble photosensitive polyimide resin according to claim 1, wherein The molar fraction of the added amount of the diamine monomer with hydroxyl group to the total added amount of the diamine monomer with hydroxyl group and the diamine monomer without hydroxyl group is 30% to 100%; and / or, the molar ratio of the sum of the molar amounts of the diamine monomer having a hydroxyl group and the diamine monomer not having a hydroxyl group to the dianhydride monomer is 1:(1.4-2); And / or, the molar ratio of the number of anhydride groups in the added unsaturated acid anhydride to the number of hydroxyl groups in the diamine having a hydroxyl group is (1-2):

1.

3. The alkali-soluble photosensitive polyimide resin according to claim 2, wherein The diamine monomer without hydroxyl group is selected from 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, aminopropyl di-terminated polydimethylsiloxane, 3,5-diamino-1,2,4-triazole, 2,6-diaminopyridine, 2-(4-aminophenyl)-5-aminobenzimidazole, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 2-amino-4-[(3,4-diaminophenyl)sulfonyl]aniline, 6, 6'-Bisamino-3,3'-methylenedibenzoic acid, 1H-indazole-4,7-diamine, 7-nitro-1H-indazole-4-amine, 2,2'-diamino-4,4'-bithiazole, 3,6-diaminocarbazole, 2-(3,6-diamino-9H-carbazole-9-yl)acetic acid methyl ester, 2,5-diaminobenzothiazole, 2,6-benzothiazole diamine, tert-butyl (6-amino-4-methylbenzo[D]thiazol-2-yl)carbamate, 4-methoxy-1,3-benzothiazole-2 ,6-diamine, phenyl guanamine, 2,4-diamino-6-(2-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-(4-chlorophenyl)-1,3,5-triazine, 2,4-diamino-6-[4-(trifluoromethyl)phenyl]-1,3,5-triazine, 2,4-diamino-6-(3-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine, 2,4-diamino-6-(4- One or more of 2,4-diamino-6-(3,5-difluorophenyl)-1,3,5-triazine, 2,4-diamino-6-(4-bromophenyl)-1,3,5-triazine, 2,4-diamino-6-(4-methoxyphenyl)-1,3,5-triazine, 2,3-diaminophenolazine, methylguanamine, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine, and 4,6-diaminopyrimidine; and / or, the diamine monomer with a hydroxyl group is selected from N-(2-hydroxyethyl)ethylenediamine, N-(2-hydroxyethyl)-1,3-propylenediamine, N,N'-bis(2-hydroxyethyl)ethylenediamine, N,N'-bis(2-hydroxyethyl)-1,3-propylenediamine, 4,6-diaminoresorcinol, 4,6-diaminoresorcinol dihydrochloride, bis(5-amino-2-hydroxyphenyl)methane hydrochloride, 3,3'-dihydroxybenzidine, 2,4-diamino-6-hydroxypyrimidine, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,4-diamino-6-hydroxymethylpteridine, 2,5-diamino-4,6-dihydroxypyrimidine hydrochloride, 2,5-diamino-1,4-dihydroxybenzene dihydrochloride, 3,3 at least one of '-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3'-diamino-4,4'-dihydroxydiphenyl ether, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfide, 3,3'-diamino-4,4'-dihydroxybiphenyl, 3,3'-diamino-4,4'-dihydroxydiphenylmethane, 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone, 5,5'-diamino-3,3,3',3'-tetramethyl-2,2',3,3'-tetrahydro-1,1'-spirobi[indene]-6,6'-diol, 4,4'-(9H-fluorene-9,9-diyl)bis(2-aminophenol), and 9,9-dimethyl-9H-fluorene-2,7-diol; and / or, the dianhydride monomer is selected from pyromellitic dianhydride, maleic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 4,4'-diphenylenedioxydiphthalic anhydride, One or more of the following dianhydrides: 1,2-ethylenebis[1,3-dihydro-1,3-dioxoisobenzofuran-5-carboxylate], bisphenol A dianhydride, glycerol bis(dehydrated trimellitate) acetate, 2,3,3',4'-biphenyltetracarboxylic dianhydride, p-phenylene-bis(triphthalate) dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(acetylene-1,2-diyl) diphthalic anhydride, 4,4'-oxydiphthalic anhydride, etc. And / or, the unsaturated acid anhydride is at least one selected from cis-4-cyclohexene-1,2-dicarboxylic anhydride, maleic anhydride, and 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexenyl-1,2-dicarboxylic anhydride.

4. The alkali-soluble photosensitive polyimide resin according to any one of claims 1 to 3, wherein The dianhydride monomer is 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride; the diamine monomer without hydroxyl group is 4,4'-diaminodiphenyl ether; the diamine monomer containing hydroxyl group is 3,3'-dihydroxybenzidine; and the unsaturated acid anhydride is cis-4-cyclohexene-1,2-dicarboxylic anhydride.

5. A method for preparing an alkali-soluble photosensitive polyimide resin according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: Under an inert atmosphere, a diamine monomer without a hydroxyl group, a diamine monomer with a hydroxyl group, and a dianhydride monomer are mixed to obtain a pre-reaction liquid, and the pre-reaction liquid is reacted for a period of time to obtain a first reaction liquid containing polyamic acid; adding a dehydrating agent to the first reaction liquid to dehydrate and cyclize the polyamic acid into polyimide, thereby obtaining a second reaction liquid containing polyimide; An unsaturated second acid anhydride is added to the second reaction liquid to react the hydroxyl groups in the molecular main chain of the polyimide with the second acid anhydride, thereby introducing unsaturated double bonds and carboxyl groups into the molecular structure of the polyimide to obtain the alkali-soluble photosensitive polyimide resin.

6. The preparation method according to claim 5, wherein The method comprises mixing a diamine monomer without hydroxyl group, a diamine monomer with hydroxyl group, and a dianhydride monomer to obtain a pre-reaction liquid, and reacting the pre-reaction liquid for a period of time to obtain a first reaction liquid containing polyamic acid, comprising: dissolving the diamine monomer without hydroxyl group in a first solvent, adding the diamine monomer with hydroxyl group to the solution after the diamine monomer without hydroxyl group is completely dissolved, stirring and dispersing the solution for 1 to 3 hours, and then adding the dianhydride monomer and stirring for 12 to 24 hours to obtain a clear and viscous first reaction liquid; And / or, the dehydrating agent is at least one selected from the group consisting of anhydride-tertiary amine dehydrating agent, thionyl chloride-tertiary amine dehydrating agent and acetyl chloride-tertiary amine dehydrating agent; and / or, the reaction temperature for the dehydration cyclization of polyamic acid is 90° C. to 100° C., and the reaction time is 10 h to 24 h; And / or, the second acid anhydride is a dibasic acid anhydride, and the second acid anhydride can be one or more of cis-4-cyclohexene-1,2-dicarboxylic anhydride and maleic anhydride; And / or, the amount of the second acid anhydride added is calculated based on the molar number of the acid anhydride groups, and the molar ratio of the molar number of the acid anhydride groups in the second acid anhydride to the hydroxyl groups in the diamine having a hydroxyl group is (1-2):

1.

7. A weakly alkali-soluble photosensitive polyimide resin composition, characterized in that: The weakly alkali-soluble photosensitive polyimide resin composition comprises the alkali-soluble photosensitive polyimide resin according to any one of claims 1 to 4, or the alkali-soluble photosensitive polyimide resin prepared by the preparation method according to claim 5 or 6.

8. The weakly alkali-soluble photosensitive polyimide resin composition according to claim 7, wherein The weakly alkali-soluble photosensitive polyimide resin composition comprises the alkali-soluble photosensitive polyimide resin, a photoinitiator and a photocrosslinker. Calculated by mass ratio, the alkali-soluble photosensitive polyimide resin: photoinitiator: photocrosslinker is 100: (3-7): (7-13).

9. A weakly alkali-soluble photosensitive resin composition, characterized in that: The weakly alkali-soluble photosensitive resin composition comprises 100 parts of an alkali-soluble multifunctional photosensitive epoxy resin; 10 to 60 parts of the alkali-soluble photosensitive polyimide resin according to any one of claims 1 to 4, or the alkali-soluble photosensitive polyimide resin prepared by the preparation method according to claim 5 or 6; 1 to 40 parts of a photopolymerization initiator; 5 to 50 parts of photopolymerizable monomer; 10 to 80 parts of heat-curing component; and 10 to 100 parts of filler.

10. A photosensitive dry film, characterized in that: The photosensitive dry film is prepared from the weakly alkali-soluble photosensitive polyimide resin composition according to claim 7 or 8, or is prepared from the weakly alkali-soluble photosensitive resin composition according to claim 9.

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