Positive photosensitive polyimide composition with high elongation at break and application thereof

Abstract

The invention relates to a positive photosensitive polyimide composition with high elongation at break and application of the positive photosensitive polyimide composition. The photosensitive polyimide composition comprises polyamide acid resin, diazonaphthoquinone sulfonate, a thermal crosslinking agent, a surfactant, a flexibility aid and a solvent. According to the positive photosensitive polyimide composition disclosed by the invention, on one hand, the flexibility auxiliary agent can be used for remarkably improving the elongation at break of a photosensitive polyimide film on the premise of not influencing the tensile strength of the photosensitive polyimide film and improving the mechanical properties of flexibility and bending resistance of the photosensitive polyimide film; on the other hand, the uniformity that a solvent volatilizes and escapes from the interior of a film after the photosensitive polyimide composition is glued is improved, and the flatness of the cured photosensitive polyimide is improved; in addition, a certain effect of reducing the curing temperature of the photosensitive polyimide is achieved.

Description

Technical Field

[0001] The present invention relates to the field of positive photosensitive polyimide (PSPI), and in particular to a photosensitive polyimide composition for a planarization layer PLN, a pixel definition layer PDL, a redistribution layer RDL of a fan-in / fan-out wafer-level package, an electronic component interlayer insulating layer, and a semiconductor surface protective film of an OLED display panel. Background Art

[0002] Polyimide material is a very important polymer material because of its excellent high and low temperature resistance, chemical resistance, excellent mechanical properties and good dielectric properties, especially in the semiconductor and microelectronics industries. Photosensitive polyimide (PSPI) is formed by introducing photosensitive groups into the polyimide molecular chain, or mixing polyimide precursors and photosensitive compounds and then curing at high temperature. Compared with traditional photoresists, photosensitive polyimide not only has excellent pattern transfer capabilities, but also eliminates the step of etching to remove residual glue after pattern transfer, greatly simplifying the photolithography process.

[0003] Photosensitive polyimide can be used for semiconductor buffer coating, passivation layer, α-ray shielding material, interlayer insulation material, wafer packaging material, etc. It is also widely used in the microelectronics industry, including the packaging of integrated circuits and multi-chip packages. Due to the high barriers to the lithography equipment and process technology involved and the late start of the relevant domestic material industry, the photosensitive polyimide industry is still dominated by Japanese and American companies.

[0004] The main body of polyimide resin currently used in the industry is generally formed by polycondensation reaction of aromatic tetraacid dianhydride and aromatic diamine in organic solution to generate polyamic acid or polyamide ester, and then imidization (cyclization) is performed by a certain method to obtain polyimide. The rigid structure and aromatic structure of the cyclic imide on the main chain of polyimide give it the advantages of high mechanical strength, good wear resistance and aging resistance, and low thermal expansion coefficient, but on the other hand, such a large number of rigid structures limit its better toughness and tensile properties, which is mainly reflected in the low elongation at break during stretching and poor bending resistance.

[0005] In particular, the flexible OLED (organic light-emitting diode) panels in the display industry are developing rapidly, and the flexibility requirements for each layer of materials in OLED devices are extremely high, which requires photosensitive polyimide to improve its flexibility while maintaining other properties.

[0006] In the prior art, patent CN111936552A provides a polyimide composition, in which an aliphatic diacid having a linear alkyl group is introduced into the structure of a polyamide, thereby obtaining a cured film with high elongation; patent WO 2011059089A1 provides a photosensitive polyimide precursor composition, in which an aliphatic diamine having a specific long-chain alkyl ether structure is introduced into the polyimide resin skeleton, and the prepared polyimide film has strong bending resistance.

[0007] The above patents all directly introduce some flexible chain segments into the polyimide main chain. Although this improves the flexibility of the film to a certain extent, it inevitably reduces the thermodynamic properties and chemical resistance of the polyimide. In addition, the production process by introducing a long chain structure into the resin main chain is not stable. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a new photosensitive polyimide composition. When a polyamic acid resin known in the industry is used as the main body, a small amount of flexibility additive is added to the composition, which can significantly improve the elongation at break of the polyimide film and enhance the bending resistance of the material.

[0009] To achieve the above purpose, the technical solution used in the present invention is as follows:

[0010] A positive photosensitive polyimide composition with high elongation at break comprises polyamic acid resin, diazo naphthoquinone sulfonic acid ester, a thermal crosslinking agent, a flexibility aid, a surfactant and a solvent.

[0011] In a preferred embodiment, the total mass of the positive photosensitive polyimide composition is 100%, including 2% to 40% of polyamic acid resin, 5% to 40% (based on the mass of the polyamic acid resin) of diazo naphthoquinone sulfonate, 5% to 40% (based on the mass of the polyamic acid resin) of thermal crosslinking agent, 0.2% to 2% (based on the mass of the polyamic acid resin) of flexibility aid, 0.001% to 1% (based on the mass of the polyamic acid resin) of surfactant, and the balance of solvent;

[0012] In a more preferred embodiment, based on the total mass of the photosensitive polyimide composition as 100%, it includes 5% to 25% by mass of polyamic acid resin, 10% to 30% by mass of naphthoquinone sulfonate (based on the mass of polyamic acid resin), 10% to 25% by mass of a thermal crosslinking agent (based on the mass of polyamic acid resin), 0.5% to 1% by mass of a flexibility aid (based on the mass of polyamic acid resin), 0.05% to 0.5% by mass of a surfactant (based on the mass of polyamic acid resin), and the remainder of a solvent.

[0013] In a specific embodiment, the polyamic acid resin component comprises a structure of chemical formula (I):

[0014]

[0015] In formula (I), R1 represents an acid dianhydride having an alicyclic structure, R2 represents a monocyclic or polycyclic aromatic diamine compound, R3 or R4 represents hydrogen, a hydrocarbon group having 1 to 10 carbon atoms, or an alkylsilyl group having 1 to 10 carbon atoms; n is an integer greater than 2, preferably 5 to 30.

[0016] In a preferred embodiment, R1 is selected from any one of 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, and 3,4-dicarboxylic acid-1,2,3,4-tetrahydro-1-naphthalene dibutyric dianhydride; preferably, R1 is 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride.

[0017] In a preferred embodiment, R2 is selected from any one of 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenyl sulfide, and 4,4'-diaminobenzanilide; preferably, R2 is 2,2'-bis(trifluoromethyl)benzidine.

[0018] In a specific embodiment, the structural formula of the flexibility aid is

[0019]

[0020] Wherein R1 is hydrogen, C1-C4 alkyl, a substituent having no more than 8 carbon atoms and containing nitrogen or oxygen atoms; R2 is any one of acrylate, methacrylate or acrylamide; and n is an integer of 1-100.

[0021] In a preferred embodiment, the flexibility aid is one or more of amino-polyethylene glycol-acrylate, amino-polyethylene glycol-methacrylate, maleimide-polyethylene glycol-acrylate, and acrylate-polyethylene glycol-lysine; preferably, the flexibility aid has a number average molecular weight Mw of 400 to 5000.

[0022] In a specific embodiment, the diazonaphthoquinone sulfonate is at least one of diazonaphthoquinone-4-sulfonate or diazonaphthoquinone-5-sulfonate; preferably, the diazonaphthoquinone sulfonate is diazonaphthoquinone-5-sulfonate.

[0023] In a specific embodiment, the thermal crosslinking agent is a polyhydroxy or polymethoxy compound commonly used in the art: preferably one or more of 4,4',4"-(ethane-1,1,1-triyl)tris(2,6-bis(methoxymethyl)phenol) HMOM-TPHAP, 3,3',5,5'-tetramethoxymethylbiphenol TMOM-BP, 1,3,4,6-tetrakis(methoxymethyl)glycoluril, preferably HMOM-TPHAP.

[0024]

[0025] In a specific embodiment, the surfactant is one or more of BYK-378, BYK-306, BYK-333, BYK-3760 (BYK Chemical series surfactant additives), KP-341, KP-358, KP-545, KP-549 (Shin-Etsu Chemical series additives); preferably, the surfactant is BYK-378.

[0026] In a specific embodiment, the solvent is one or more of N-methyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, dioxane, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetone, methyl ethyl ketone, diisobutyl ketone, ethyl acetate, butyl acetate, isobutyl acetate, propyl acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl lactate, and methyl lactate, preferably N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monomethyl ether or ethyl lactate.

[0027] In another aspect of the present invention, the positive photosensitive polyimide composition with high elongation at break can be used as pattern transfer photoresist and dielectric layer materials in the flat layer PLN, pixel definition layer PDL of OLED display panels, redistribution layer RDL of fan-in / fan-out wafer-level packaging, electronic component interlayer insulation layer and semiconductor surface protection film.

[0028] By adopting the above technical solution, the present invention has the following beneficial effects:

[0029] 1) The flexibility additive in the present invention can significantly improve the elongation at break of the polyimide film. During the high-temperature curing of polyimide (250-350°C), the flexibility additive can also be cured by thermal reaction, entangled and cross-linked with the main chain of the polyimide resin, increase the free volume between the polyimide segments, and make the internal segments move more freely when the polyimide film is stretched by external force; in addition, the amino group (amine group) it has can continue to amidate with the residual carboxyl group on the main chain of the polyimide resin, thereby improving the imidization rate.

[0030] 2) The short-chain structure of polyethylene glycol in the flexibility additive of the present invention slows down the drying speed of the film surface during the pre-baking stage (110-130°C, 90s-180s) after the photosensitive polyimide composition is applied, thereby preventing the film surface from drying too quickly and restricting the movement of the chain segments, thereby hindering the escape of the solvent; and makes the drying speeds at different depths of the film tend to be consistent, thereby avoiding the unevenness of the film surface during the pre-baking stage and affecting the thickness uniformity of the cured film.

[0031] 3) In the present invention, the elongation at break of polyimide is improved by adding a flexibility additive, and the adjustment and control are simpler and easier to implement, without affecting the main structure of the polyimide resin and other thermodynamics, durability and dielectric properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the pre-baking stage of the positive photosensitive polyimide composition of the present invention.

[0033] Among them, 1 is the hot plate of the heating table, 2 is the boss, 3 is the substrate, and 4 is the adhesive film after adhesive application. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the examples. It should be noted that the following examples do not constitute limitations of the present invention. Unless otherwise specified, the percentages used in all examples represent mass percentages.

[0035] A positive photosensitive polyimide composition with high elongation at break comprises polyamic acid resin, diazo naphthoquinone sulfonic acid ester, a thermal crosslinking agent, a flexibility aid, a surfactant and a solvent.

[0036] Wherein, the polyamic acid resin component comprises the structure of chemical formula (I):

[0037]

[0038] In formula (I), R1 represents an acid dianhydride having an alicyclic structure, for example, R1 is selected from any one of 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, and 3,4-dicarboxylic acid-1,2,3,4-tetrahydro-1-naphthalene dibutyric dianhydride; preferably 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride.

[0039] In formula (I), R2 represents a monocyclic or polycyclic aromatic diamine compound, for example, R2 is selected from any one of 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenyl sulfide, and 4,4'-diaminobenzanilide; preferably 2,2'-bis(trifluoromethyl)benzidine.

[0040] In formula (I), R3 or R4 represents hydrogen, a hydrocarbon group having 1 to 10 carbon atoms, or an alkylsilyl group having 1 to 10 carbon atoms; wherein the hydrocarbon group having 1 to 10 carbon atoms is, for example, methyl, ethyl, propyl, butyl, isopropyl, pentyl, isobutyl, hexyl, heptyl, octyl, nonyl, decyl, etc., but is not limited thereto; and the alkylsilyl group having 1 to 10 carbon atoms is, for example, trimethylsilyl, triethylsilyl, triisopropylsilyl, etc.

[0041] In formula (I), n is an integer of 2 or more, for example, 3, 4, 5, 8, 10, 12, 15, 16, 18, 20, 23, 25, 28, 30, 33, 35, 38, 40, 45, 50, etc., and preferably 5 to 30.

[0042] In the present invention, the molecular weight Mw of the polyamic acid resin is 5000-50000 g / mol, for example, 5000 g / mol, 6000 g / mol, 7000 g / mol, 8000 g / mol, 9000 g / mol, 10000 g / mol, 12000 g / mol, 13000 g / mol, 15000 g / mol, 16000 g / mol, 18000 g / mol, 20000 g / mol, 25000 g / mol, 30000 g / mol, 35000 g / mol, 40000 g / mol, 45000 g / mol, 50000 g / mol, etc.; preferably, 5000-20000 g / mol.

[0043] In the present invention, based on the total mass of the positive photosensitive polyimide composition, the polyamic acid resin accounts for 2% to 40%, for example, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 15%, 16%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 36%, 38%, 40%, etc., and the preferred mass fraction is 5% to 25%.

[0044] Wherein, the structural formula of the flexibility additive is

[0045] Wherein R1 is hydrogen; a substituted or unsubstituted C1-C4 alkyl group, such as methyl, ethyl, propyl, butyl or isopropyl; or a substituent having no more than 8 carbon atoms and containing nitrogen or oxygen atoms, such as a lysine group or a maleimide group; R2 is any one of an acrylate group, a methacrylate group or an acrylamide group. n is an integer of 1-100, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, etc.

[0046] In a preferred embodiment, the number average molecular weight Mw of the flexibility aid is 400-5000 g / mol, for example, 500 g / mol, 600 g / mol, 700 g / mol, 800 g / mol, 900 g / mol, 1000 g / mol, 2000 g / mol, 3000 g / mol, 4000 g / mol, etc. Preferably, the flexibility aid is amino-polyethylene glycol-acrylate with a Mw of 400-5000 g / mol; amino-polyethylene glycol-methacrylate with a Mw of 400-5000 g / mol; more preferably, the flexibility aid is one or more of amino-polyethylene glycol-acrylate with a Mw of 1000, 2000; and amino-polyethylene glycol-methacrylate with a Mw of 1000, 2000.

[0047] In the present invention, based on the mass of the polyamic acid resin, the amount of the flexibility additive added is 0.2% to 2% of the mass of the polyamic acid resin, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, etc., preferably 0.5% to 1%.

[0048] Wherein, the diazonaphthoquinone sulfonate is diazonaphthoquinone-4-sulfonate or diazonaphthoquinone-5-sulfonate, preferably diazonaphthoquinone-5-sulfonate.

[0049] In the present invention, based on the mass of the polyamic acid resin, the added amount of the naphthoquinone sulfonate is 5% to 40% of the mass of the polyamic acid resin, for example, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 15%, 16%, 18%, 19%, 20%, 23%, 25%, 26%, 28%, 29%, 30%, 32%, 33%, 35%, 36%, 38%, 39%, etc., preferably 10% to 30%.

[0050] The thermal crosslinking agent is one or more of 4,4',4"-(ethane-1,1,1-triyl)tris(2,6-di(methoxymethyl)phenol) HMOM-TPHAP, 3,3',5,5'-tetramethoxymethylbiphenol TMOM-BP, and 1,3,4,6-tetra(methoxymethyl)glycoluril, preferably HMOM-TRHAP.

[0051] In the present invention, based on the mass of the polyamic acid resin, the added amount of the thermal crosslinking agent is 5% to 40% of the mass of the polyamic acid resin, for example, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 15%, 16%, 18%, 19%, 20%, 23%, 25%, 26%, 28%, 29%, 30%, 32%, 33%, 35%, 36%, 38%, 39%, etc., preferably 10% to 25%.

[0052] Wherein, the surfactant is one or more of BYK Chemical series surfactant additives BYK-378, BYK-306, BYK-333, BYK-3760, Shin-Etsu Chemical series additives KP-341, KP358, KP-545, KP-549; preferably, the surfactant is BYK-378.

[0053] In the present invention, based on the mass of the polyamic acid resin, the amount of the surfactant is 0.001% to 1% of the mass of the polyamic acid resin, for example, 0.002%, 0.005%, 0.006%, 0.008%, 0.01%, 0.03%, 0.05%, 0.07%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc., preferably 0.1%-0.5%.

[0054] Among them, the remaining components in the positive photosensitive polyimide composition are solvents, and the solvent is one or more of N-methyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, dioxane, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetone, methyl ethyl ketone, diisobutyl ketone, ethyl acetate, butyl acetate, isobutyl acetate, propyl acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl lactate, and methyl lactate, preferably N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monomethyl ether or ethyl lactate.

[0055] The positive photosensitive polyimide composition with high elongation at break of the present invention is prepared by weighing the components according to the weight proportions before use, mixing them in a glass bottle, placing them on a shaker or roller shaker for 12 hours to mix them evenly, letting them stand for 60 minutes, filtering them with 0.22 um and continuing to shake them evenly for 4 hours, and finally placing the liquid in a reduced pressure vacuum box to reduce the pressure to 200 Pa to remove bubbles before use.

[0056] The pre-baking stage of the positive photosensitive polyimide composition of the present invention is schematically shown as follows Figure 1As shown, the surface of the substrate 3 is a photosensitive polyimide adhesive film 4 after adhesive application. The substrate 3 after adhesive application is placed by a robot directly from room temperature to a hot plate 1 of a heating table with bumps 2 (the surface of the hot plate is 110-130°C). After the robot is pulled out, the bottom area of ​​the substrate 3 that is directly in contact with the bumps 2 heats up earlier and faster, and the surface of the adhesive film corresponding to this area (if there is no flexibility additive) will dry quickly, and the thickness will decrease faster than the surrounding area, eventually forming a pit.

[0057] The positive photosensitive polyimide composition of the present invention, due to its unique formula components, especially the addition of flexibility additives, can promote the solvent to evaporate more evenly from the inside of the film during the pre-baking process, thereby reducing the film surface undulation phenomenon that may occur due to uneven local heating of the film caused by loose adhesion to the baking hot plate.

[0058] The present invention will be further explained below by more specific examples, but they do not constitute any limitation.

[0059] Unless otherwise specified, other raw materials and reagents used in the examples and comparative examples of the present invention are preferably obtained from commercial sources.

[0060] Flexibility additives:

[0061] Amino-polyethylene glycol-acrylate 1000; amino-polyethylene glycol-acrylate 2000; amino-polyethylene glycol-methacrylate 1000; amino-polyethylene glycol-acrylate 2000; acrylate-polyethylene glycol-lysine 2000; maleimide-polyethylene glycol-acrylate 2000 were all purchased from Shanghai Tuoyang Biotechnology Co., Ltd.

[0062] Diazonaphthoquinone-5-sulfonate and diazonaphthoquinone-4-sulfonate were obtained from Yantai Jiumu Chemical.

[0063] The thermal crosslinker 4,4',4"-(ethane-1,1,1-triyl)tris(2,6-bis(methoxymethyl)phenol) HMOM TRHAP was from China Energy Conservation Wanrun Co., Ltd.; 3,3',5,5'-tetramethoxymethylbiphenol TMOM-BP was from Shanghai Fengji Pharmaceutical Technology Co., Ltd.; 1,3,4,6-tetra(methoxymethyl)glycoluril was from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0064] BYK-378 comes from BYK Chemicals, and KP-545 comes from Shin-Etsu Chemical.

[0065] Among them, the preparation of polyamic acid resin refers to the common synthesis method in patent CN109348718A (polyimide resin, polyimide resin composition, touch panel using the same and manufacturing method thereof, color filter and manufacturing method thereof, liquid crystal element and manufacturing method thereof, organic EL element and manufacturing method thereof), which is as follows:

[0066] Under a dry nitrogen stream, add 2.24g (10mmol) 1S, 2S, 4R, 5R-cyclohexanetetracarboxylic acid dianhydride, 3.2g (10mmol) 2,2'-bis (trifluoromethyl) benzidine, 0.1g cyclohexanol (1mmol) and 50g N-methylpyrrolidone to a 100mL four-necked flask, and heat and stir at 60°C. After 8 hours, cool to room temperature. Pour the obtained mixture into a large amount of deionized water for precipitation and washing, and then filter out the white precipitate. The precipitation and filtration process is repeated three times, and the white polyamic acid polymer obtained is placed in a vacuum oven and dried for 72h for standby use.

[0067] The preparation of the positive photosensitive polyimide composition:

[0068] The polyamic acid, diazonaphthoquinone sulfonate, thermal crosslinking agent, flexibility aid, and surfactant were accurately weighed in sequence according to the formula using an analytical balance, and finally a mixed solvent (propylene glycol monomethyl ether, ethyl lactate, and γ-butyrolactone) was added to make up the total mass of the composition to 100%, mixed, and shaken with an oscillator for 12 hours, and then filtered with a 0.22 μm filter membrane. After filtering, the mixture was shaken for 4 hours to obtain the compositions of the embodiments and comparative examples of the present invention.

[0069] Table 1 Content of each component of Comparative Examples 1 to 4 and Examples 1 to 16 of the present invention

[0070]

[0071]

[0072]

[0073] <Performance Test>

[0074] Elongation at break test:

[0075] The composition of comparative examples 1-4 and embodiments 1-16 was spin-coated on the surface of a 4-inch silicon wafer, and the film thickness was controlled to be about 8 μm, and then pre-baked on a 120°C hot plate for 180 seconds, and then the silicon wafer with the photosensitive polyimide composition was put into an oxygen-free oven (oxygen content <20ppm) for curing at 250°C-1h. After the curing, the sample was soaked in HF for about 15 minutes, and the polyimide film was carefully removed and quickly placed in pure water for washing for 30 seconds, and then carefully blown dry with a nitrogen gas flow, and then placed on a 120°C hot plate for baking for 30 seconds. Finally, the film was cut into strips of about 8cm×1cm with a paper cutter as tensile test specimens.

[0076] The sample was placed in the middle of the KINSGEO tensile machine fixture, and the sample was carefully clamped. A 100N sensor was used, and the tensile rate was 50mm / min. The elongation at break and the tensile strength were tested. Three groups of samples were tested for each photosensitive polyimide composition, and the average value was taken.

[0077] Curing rate (imidization rate) test:

[0078] Spin-coat the compositions of comparative examples 1-4 and embodiments 1-16 on the surface of a 2-inch infrared silicon wafer, control the film thickness to about 2 μm, and spin-coat 9 wafers of each composition. Pre-bake on a 120°C hot plate for 120 seconds, and then cure 3 samples of the same kind in an oxygen-free oven at 200°C and 250°C for 1 hour respectively. Bake the remaining 3 samples of each composition at 120°C for 120 seconds, and then cure them in an oxygen-free oven at 350°C for 1 hour. Use FTIR to test the infrared absorption spectra of all samples. Calculation of curing rate: Take the infrared spectrum at 1376cm -1 The curing rate at 200 / 250°C is calculated by the change in the peak intensity ratio of the CN stretching vibration absorption peak in the imide structure. The calculation formula (II) is as follows:

[0079]

[0080] In formula (II), A 1376 is the CN stretching vibration absorption peak intensity, A 1500 is the CC stretching vibration absorption peak intensity of the benzene ring; the test temperature represents the curing temperature of 200°C or 250°C.

[0081] Photosensitivity test:

[0082] A photosensitive polyimide film with a thickness of about 2 μm is scraped on the surface of a clean glass sheet, and the film is first placed in a vacuum decompression device to remove the solvent for 120 seconds (the pressure drops below 100 Pa), and then baked on a hot stage at 120°C for 120 seconds. After cooling, the pattern of the mask is exposed with an i-line exposure machine at 40 mj energy to transfer the mask pattern to the photosensitive polyimide film. After exposure, the glass sheet is placed at 23°C and developed with a 2.38% TMAH developer (tetramethylammonium hydroxide aqueous solution) for 80 seconds. After the development is completed, the glass sheet is rinsed with pure water for 30 seconds, and the surface is dried and placed in an oxygen-free oven at 250°C for curing for 1 hour. After the curing is completed, the diameter of the actual hole engraved through the 3 μm hole of the mask at a thickness of 2 μm is observed with a high-definition microscope. The larger the hole, the better the photosensitivity of the photosensitive polyimide composition.

[0083] Thermodynamic testing

[0084] Refer to the method of making the specimen strips of the elongation at break. Spin-coat the composition of comparative examples 1-4 and embodiments 1-16 on the surface of a 4-inch silicon wafer, control the film thickness to be about 8μm, and then heat on a 120°C hot plate for 180s, and then put the silicon wafer with the photosensitive polyimide composition into an oxygen-free oven (oxygen content <20ppm) for curing at 250°C-1h. After the curing is completed, soak the sample in HF for about 15min, carefully remove the polyimide film, quickly put it in pure water for cleaning for 30s, then carefully blow dry with a nitrogen flow, and then bake it on a 120°C hot plate for 30s. Cut the film into the size required by the TMA analyzer, and measure the Tg and thermal expansion coefficient CTE. Cut the film into pieces for TGA measurement, and measure the 5% weight loss temperature of the film sample to determine the thermal stability of the material.

[0085] Determination of film thickness uniformity during pre-baking:

[0086] Four stainless steel cylinders with a diameter of 10 mm and a height of 5 mm were placed on a 120°C oven carrier plate to simulate the state of the hot plate bumps in the pre-baking furnace of the actual production line process of the panel factory (i.e. Figure 1As shown). A photosensitive polyimide film of about 2 μm thick was scraped on a 5cm×5cm×0.5mm thick glass sheet, and then the solvent was extracted in a vacuum decompression device for 120s (the pressure dropped to below 100Pa). The oven was quickly opened and the glass sheet coated with photosensitive polyimide after the solvent was extracted was immediately placed on the top of the stainless steel cylinder in the oven. After 120s, it was taken out and cooled. Observe whether there is a thickness difference between the area on the back of the glass sheet that contacts the stainless steel cylinder and other areas. If it is observed that the film surface in this area clearly forms circles or arcs with the surrounding stripes, it means that there is a huge thickness difference. And use a step meter to test the thickness: measure from one end to the other end along the diameter direction of the contact area, and measure the thickness every 1mm. In this way, the thickness of about 20 points can completely include the film surface of the contact area and the non-contact area. The maximum and minimum values ​​are selected as the difference, and the size of the difference is compared. The smaller the difference, the more uniform the thickness.

[0087] Table 2 shows the test results of elongation at break, curing rate, photosensitivity, thermodynamics and thickness uniformity in the pre-baking stage of Comparative Examples 1 to 4 and Examples 1 to 16:

[0088]

[0089]

[0090] In summary, the photosensitive polyimide composition of the present invention can significantly improve the elongation at break of the polyimide film and reduce the risk of uneven film thickness in the pre-baking stage of the photosensitive polyimide after adding a flexibility additive, thereby increasing the application yield in actual industry; and the curing rate at low temperature (200°C) is close to 90%.

[0091] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the present invention is not limited to these embodiments and various modifications, changes and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should only be limited by the claims and their equivalents.

Claims

1. A positive photosensitive polyimide composition with high elongation at break, characterized in that: The invention comprises the following components: polyamic acid resin, diazonaphthoquinone sulfonic acid ester, thermal cross-linking agent, surfactant, flexibility assistant and solvent.

2. The positive photosensitive polyimide composition according to claim 1, characterized in that: Taking the total mass of the positive photosensitive polyimide composition as 100%, the composition comprises: 2% to 40% of a polyamic acid resin, 5% to 40% (based on the mass of the polyamic acid resin) of a naphthoquinone sulfonate, 5% to 40% (based on the mass of the polyamic acid resin) of a thermal crosslinking agent, 0.2% to 2% (based on the mass of the polyamic acid resin) of a flexibility aid, 0.001% to 1% (based on the mass of the polyamic acid resin) of a surfactant, and a solvent; Preferably, based on the total mass of the positive photosensitive polyimide composition as 100%, it includes 5% to 25% by mass of polyamic acid resin, 10% to 30% by mass of naphthoquinone sulfonate (based on the mass of polyamic acid resin), 10% to 25% by mass of a thermal crosslinking agent (based on the mass of polyamic acid resin), 0.5% to 1% by mass of a flexibility aid (based on the mass of polyamic acid resin), 0.05% to 0.5% by mass of a surfactant (based on the mass of polyamic acid resin), and the remainder of a solvent.

3. The positive photosensitive polyimide composition according to claim 1 or 2, characterized in that: The structural formula of the flexibility aid is Wherein R1 is hydrogen, a substituted or unsubstituted C1-C4 alkyl group, or a substituent having no more than 8 carbon atoms and containing nitrogen or oxygen atoms; R2 is any one of an acrylate group, a methacrylate group or an acrylamide group; and n is an integer of 1-100.

4. The positive photosensitive polyimide composition according to claim 3, characterized in that: The flexibility aid is one or more of amino-polyethylene glycol-acrylate and amino-polyethylene glycol-methacrylate; Preferably, the number average molecular weight Mw of the flexibility aid is 400-5000.

5. The positive photosensitive polyimide composition according to any one of claims 1 to 4, characterized in that: The polyamic acid resin component comprises a structure of chemical formula (I): In the formula, R1 represents an acid dianhydride having an alicyclic structure, R2 represents a monocyclic or polycyclic aromatic diamine compound, R3 or R4 represents hydrogen, a hydrocarbon group having 1 to 10 carbon atoms, or an alkylsilyl group having 1 to 10 carbon atoms; n is an integer greater than 2, preferably 5 to 30.

6. The positive photosensitive polyimide composition according to any one of claims 1 to 5, characterized in that: The diazonaphthoquinone sulfonate is at least one of diazonaphthoquinone-4-sulfonate or diazonaphthoquinone-5-sulfonate, preferably diazonaphthoquinone-5-sulfonate.

7. The positive photosensitive polyimide composition according to any one of claims 1 to 6, characterized in that: The thermal crosslinking agent is one or more of 4,4',4"-(ethane-1,1,1-triyl)tris(2,6-bis(methoxymethyl)phenol) HMOM-TPHAP, 3,3',5,5'-tetramethoxymethylbiphenol TMOM-BP, and 1,3,4,6-tetra(methoxymethyl)glycoluril, preferably HMOM-TRHAP.

8. The positive photosensitive polyimide composition according to any one of claims 1 to 7, characterized in that: The surfactant is one or more of BYK-378, BYK-306, BYK-333, BYK-3760, KP-341, KP358, KP-545, and KP-549; preferably, the surfactant is BYK-378.

9. The positive photosensitive polyimide composition according to any one of claims 1 to 8, characterized in that: The solvent is one or more of N-methyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, dioxane, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetone, methyl ethyl ketone, diisobutyl ketone, ethyl acetate, butyl acetate, isobutyl acetate, propyl acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl lactate, and methyl lactate, preferably N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monomethyl ether or ethyl lactate.

10. The use of the positive photosensitive polyimide composition with high elongation at break described in any one of claims 1 to 9 in the planarization layer PLN, pixel definition layer PDL of OLED display panels, the redistribution layer RDL of fan-in / fan-out wafer-level packaging, the interlayer insulation layer of electronic components or the surface protection film of semiconductors, preferably as a pattern transfer photoresist and dielectric layer material.

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