Photoresist composition, preparation method thereof and photosensitive dry film

Abstract

The invention belongs to the technical field of photoetching materials, and particularly relates to a photoresist composition, a preparation method thereof and a photosensitive dry film. The photoresist composition comprises photosensitive resin at least containing one olefinic unsaturated group, alkali-soluble resin, a photoinitiator and an auxiliary agent, the photoinitiator is a photopolymerization compound with a biimidazole structure. The components of the photoresist composition provided by the invention have good intersolubility, and the photoresist composition has good adhesive force, is easy to process, and has good corrosion resistance, electroplating resistance, cold flow resistance, heat resistance and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of photolithography materials, and in particular relates to a photoresist composition, a preparation method thereof and a photosensitive dry film. Background Art

[0002] Printed circuit boards (PCBs) are substrates for connecting and installing various microelectronic devices. PCB photoresists are mainly divided into three categories: wet film photoresists, dry film photoresists (photosensitive dry films), and photoimageable solder resist inks. Photosensitive dry films are the most important type of PBC photoresists.

[0003] Photosensitive dry film is a negative solid photoresist, which consists of a three-layer structure of base film, photosensitive resin layer and protective film. The base film is generally polyethylene terephthalate (PET), and the protective film is generally polyethylene (PE) or polypropylene (PP). The photosensitive resin layer is the main body of the photosensitive dry film, sandwiched between the base film and the protective film, and is mainly composed of alkali-soluble resin, photopolymerization monomer, initiator, solvent, dye and other additives. Common alkali-soluble resins include polyurethane acrylic resin, epoxy resin and epoxy resin. Monomers are also called active diluents, which are usually some low-viscosity small molecular organic substances containing photopolymerizable groups. For a photopolymerization formula, the introduction of monomers can not only reduce the viscosity of the system, but also affect the physical and chemical properties of the final photocurable material because they contain polymerizable groups and can participate in the photopolymerization reaction. Photoinitiators play the role of initiating polymerization reactions in photopolymerization formulas and are the core components of photopolymerization formulas. As the requirements for integration and refinement of printed circuit boards become higher and higher, the resolution, adhesion, hole coverage, corrosion resistance and other properties of existing dry films can no longer meet the current development needs. Summary of the invention

[0004] To solve the deficiencies of the prior art, the present invention provides a photoresist composition, a preparation method thereof and a photosensitive dry film. The photoresist composition provided by the present invention has good mutual solubility of the components, good adhesion and is easy to handle, and has good corrosion resistance, plating resistance, cold flow resistance, heat resistance and other properties.

[0005] The technical solution provided by the present invention is as follows:

[0006] A photoresist composition comprises: a photosensitive resin containing at least one ethylenically unsaturated group, an alkali-soluble resin, a photoinitiator, and an auxiliary agent; the photoinitiator is a photopolymerizable compound of a biimidazole structure, and its specific structure is shown in Formula 1:

[0007]

[0008] in:

[0009] R1, R2, R3, R4, R5, and R6 are each independently selected from substituted or unsubstituted C 6-18 The aryl group is selected from C1-C 12 Alkyl, C1-C 12 At least one or more combinations of alkoxy, cyano, nitro and halogen; and at least one of R1, R3, R4, and R5 is selected from an aryl group in which x hydrogen atoms are replaced by R0, x is at least 2, each R0 is an alkoxy group or a nitro group, and each R0 is the same or different.

[0010] In the above technical solution:

[0011] The bisimidazole photoinitiator used has good photosensitivity, so that the composition has high photosensitivity and low exposure energy, which can meet the exposure energy of the photosensitive adhesive film process, and at the same time, the cured film has good resolution, thermal stability and electrochemical performance;

[0012] By mixing a biimidazole photoinitiator with an alkali-soluble resin, the resolution and adhesion of the photosensitive dry film can be improved together.

[0013] Specifically: the aryl group in which m hydrogen atoms are replaced by R0 has the structural formula shown in Formula 2:

[0014]

[0015] Wherein, * is the connection site, R7 is H or C1-C 12 Alkoxy, R8 is C1-C 12 Alkyl, C1-C 12 Alkoxy, cyano, nitro or halogen; the halogen is selected from Cl, Br; R7 is C3-C 10 When it is an alkoxy group, n≥1, and at least one of the R8 is an alkoxy group or a nitro group; when the R7 is H, n≥2, and at least two of the R8 are alkoxy groups or nitro groups.

[0016] More preferably, when n≥2, at least two of said R8 are selected from nitro.

[0017] Preferably, R1 and R4 both have the structural formula shown in Formula 2, and R1 and R4 are the same or different.

[0018] In the preferred technical solution, when any one or more of R1, R2, R3, R4, R5, and R6 are selected from the structural formula shown in Formula 2, the remaining options are preferably unsubstituted, or, 12 Alkyl, C1-C 12 C substituted with one or more of alkoxy, nitro or halogen 6-18 The aromatic group.

[0019] And, the number of substituents is 1, 2 or 3.

[0020] Furthermore, the C 6-18 The aromatic group is selected from monocyclic aromatic hydrocarbons, condensed aromatic hydrocarbons, or a group consisting of any one or more of monocyclic aromatic hydrocarbons and condensed aromatic hydrocarbons.

[0021] Preferably, the monocyclic aromatic hydrocarbons are selected from benzene rings, and the condensed aromatic hydrocarbons are selected from naphthalene and anthracene; the group formed by any one or more of the monocyclic aromatic hydrocarbons and the condensed aromatic hydrocarbons includes, but is not limited to, a single bond between two benzene rings, a C1-C 12 Alkyl, C1-C 12 The benzene ring and naphthalene are connected by one or more of the following methods: -alkoxy, -O-, -S-, or the benzene ring and naphthalene are connected by a single bond, C1-C 12 Alkyl, C1-C 12 The connection can be one or more of alkoxy, -O-, and -S-.

[0022] Preferably, the R1 is the same as the R4.

[0023] Furthermore, the R2 is the same as the R6, the R3 is the same as the R5, and the R2 is the same as or different from the R3.

[0024] Specifically: the photosensitive resin includes resin oligomers and / or photopolymerizable monomers.

[0025] In the technical solution of the present application, a combination of a resin oligomer and a photopolymerizable monomer is preferred.

[0026] The resin oligomer may be polymerized from one or more photopolymerizable monomers. There is no limitation on the weight average molecular weight of the resin oligomer.

[0027] Specifically: the photopolymerizable monomers include one or more polymerizable monomers having aromatic groups and / or alicyclic hydrocarbon groups and / or alkane groups.

[0028] Preferably, the photopolymerizable monomer can be selected from polymerizable resin monomers such as (meth) acrylic acid-based polymerizable monomers, styrene-based polymerizable monomers, epoxy-based polymerizable monomers, aliphatic polyurethane (meth) acrylate polymerizable monomers, aromatic polyurethane (meth) acrylate polymerizable monomers, phenolic resin monomers, polyester (meth) acrylate polymerizable monomers, polyether (meth) acrylate polymerizable monomers, etc. These compounds can be used alone or in combination of two or more.

[0029] In the technical solution of the present invention, the auxiliary agents in the photoresist composition can be specifically selected according to the desired function, and examples thereof include surfactants, photoacid generators, adhesion enhancers, defoamers, leveling agents, plasticizers, antioxidants, stabilizers, inhibitors, etc.

[0030] The specific types of the above additives are not limited, and any commonly used additives in the field of photosensitive resin compositions can be selected according to the desired functions. For example, plasticizers can improve the softness and plasticity of the photosensitive resin composition, making it easier to process and shape. They can increase the ductility and flexibility of the material, improve its physical properties and processing properties. Defoamers can reduce bubbles and foam in the coating, improve the quality and appearance of the coating. Leveling agents can reduce the surface tension of the coating, making it easier to evenly distribute and flow on the surface, reducing defects and unevenness of the coating.

[0031] In addition, without listing them one by one, by adding these additives, the performance and application characteristics of the photosensitive resin composition can be improved to make it suitable for different needs.

[0032] In the technical solution of the present invention, the alkali soluble resin is not limited in selection, and the alkali soluble resin commonly used in the art is preferred. The alkali soluble resin used in the photosensitive resin composition of the present invention can be selected from acrylic acid containing alkali soluble groups.

[0033] The second object of the present invention is to provide a method for preparing a photoresist composition, comprising the following steps: uniformly mixing a photosensitive resin, an alkali-soluble resin, a photoinitiator and an auxiliary agent according to a weight ratio, filtering and degassing to obtain the photoresist composition.

[0034] The third object of the present invention is to provide a photosensitive dry film, which includes a support and a photosensitive layer, wherein the photosensitive layer is prepared from the photoresist composition prepared above. The support is a conventional material in the art, such as polyethylene terephthalate (PET).

[0035] Specifically, the photosensitive dry film coating is coated or sprayed on the surface of a polyester PET film, and placed in an oven at a temperature of 70-85° C. to dry for 5-10 minutes to obtain the photosensitive dry film.

[0036] The beneficial effects of the present invention are as follows:

[0037] The photoresist composition and photosensitive dry film provided by the present invention improve the resolution and adhesion of the photosensitive dry film by mixing a biimidazole photoinitiator with an alkali-soluble resin. The biimidazole photoinitiator used in the present application has good photosensitivity, so that the composition has high photosensitivity and low required exposure energy, which can meet the exposure energy of the photosensitive film process, and at the same time, the cured film has good resolution, thermal stability and electrochemical properties. The photoresist composition has sufficient photosensitivity, resolution, adhesion, heat resistance, etching resistance and other properties. DETAILED DESCRIPTION

[0038] The principles and features of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0039] Photoinitiator G1:

[0040]

[0041] Preparation of intermediate S1-1: 3,5-dinitrobenzaldehyde (0.01 mol, 1.96 g), 1-(2-chlorophenyl)-2-phenylethane-1,2-dione (0.01 mol, 2.45 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, and the mixture was heated to 90°C under nitrogen protection and refluxed for 1 h. After the reaction was completed as monitored by TCL, the mixture was cooled, washed with water until neutral, dried and recrystallized with ethanol to obtain 3.53 g of intermediate S1-1 with a yield of 86%.

[0042] Preparation of intermediate S1-2: 2-chlorobenzaldehyde (0.01 mol, 1.41 g), 1-(2-chlorophenyl)-2-phenylethane-1,2-dione (0.01 mol, 2.45 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, and the mixture was heated to 90°C under nitrogen protection and refluxed for 1 h. After the reaction was completed as monitored by TCL, the mixture was cooled, washed with water until neutral, dried and recrystallized with ethanol to obtain 3.18 g of intermediate S1-2 with a yield of 87%;

[0043] Preparation of photoinitiator G1: Add 50 ml of toluene solution to a dry round-bottom flask, add intermediate S1-1 (3.5 mmol, 1.47 g), potassium ferrocyanide (70 mmol, 23.05 g), and 7.6 g of potassium hydroxide and stir to dissolve evenly, dissolve intermediate S1-2 (3.5 mmol, 1.28 g) in 50 ml of toluene solution, mix and stir the two solutions, reflux for 5 h, and after TCL monitoring the reaction is complete, separate the liquids, collect the organic phase, and spin dry to obtain 2.00 g of compound G1, with a yield of 73%. The molecular weight was determined by mass spectrometer (MALDI-TOF-MS) to be 783.092, which was determined to be the target compound G1.

[0044] Photoinitiator G2:

[0045]

[0046] Preparation of intermediate S2-1: 2-butoxy-5-nitrobenzaldehyde (0.01 mol, 2.23 g), 1-(2-chlorophenyl)-2-(3,4-dimethoxyphenyl)ethane-1,2-dione (0.01 mol, 3.05 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, and the mixture was heated to 90°C under nitrogen protection and refluxed for 1 h. After the reaction was completed as monitored by TCL, the mixture was cooled, washed with water until neutral, dried and recrystallized with ethanol to obtain 4.22 g of intermediate S2-1 with a yield of 83%;

[0047] Preparation of intermediate S2-2: 2-chlorobenzaldehyde (0.01 mol, 1.41 g), 1-(2-chlorophenyl)-2-(3,4-dimethoxyphenyl)ethane-1,2-dione (0.01 mol, 3.05 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, and the mixture was heated to 90° C. under nitrogen protection and refluxed for 1 h. After the reaction was completed as monitored by TCL, the mixture was cooled, washed with water until neutral, dried and recrystallized with ethanol to obtain 3.57 g of intermediate S2-2 with a yield of 84%;

[0048] Preparation of photoinitiator G2: Add 50 ml of toluene solution to a dry round-bottom flask, add intermediate S2-1 (3.5 mmol, 1.78 g), potassium ferrocyanide (70 mmol, 23.05 g), and 7.6 g of potassium hydroxide and stir to dissolve evenly, dissolve intermediate S2-2 (3.5 mmol, 1.49 g) in 50 ml of toluene solution, mix and stir the two solutions, reflux for 5 h, and after TCL monitoring the reaction is complete, separate the liquids, collect the organic phase, and spin dry to obtain 2.51 g of compound G2, with a yield of 77%. The molecular weight was determined by mass spectrometer (MALDI-TOF-MS) to be 930.852, which was determined to be the target compound G2.

[0049] Photoinitiator G3:

[0050]

[0051] Preparation of intermediate S3-1: 2-butoxy-3,5-dinitrobenzaldehyde (0.01 mol, 2.68 g), aromatic aldehyde (0.01 mol, 2.10 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, and the mixture was heated to 90°C under nitrogen protection and refluxed for 1 h. After the reaction was completed as monitored by TCL, the mixture was cooled, washed with water until neutral, dried and recrystallized with ethanol to obtain 3.90 g of intermediate S3-1 with a yield of 85%.

[0052] Preparation of intermediate S3-2: Benzaldehyde (0.01 mol, 1.06 g), aromatic aldehyde (0.01 mol, 2.10 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, and the mixture was heated to 90°C under nitrogen protection and refluxed for 1 h. After the reaction was completed as monitored by TCL, the mixture was cooled, washed with water until neutral, dried and recrystallized with ethanol to obtain 2.67 g of intermediate S3-2 with a yield of 90%;

[0053] Preparation of photoinitiator G3: Add 50 ml of toluene solution to a dry round-bottom flask, add intermediate S3-1 (3.5 mmol, 1.60 g), potassium ferrocyanide (70 mmol, 23.05 g), and 7.6 g of potassium hydroxide and stir to dissolve evenly, dissolve intermediate S3-2 (3.5 mmol, 1.04 g) in 50 ml of toluene solution, mix and stir the two solutions, reflux for 5 h, and after TCL monitoring the reaction is complete, separate the liquids, collect the organic phase, and spin dry to obtain 1.98 g of compound G3, with a yield of 75%. The molecular weight was determined by mass spectrometer (MALDI-TOF-MS) to be 752.667, which was determined to be the target compound G3.

[0054] Photoinitiator G4:

[0055]

[0056] Preparation of intermediate S4-1: 3,5-dinitrobenzaldehyde (0.01 mol, 1.96 g), 1-(3,4-dimethoxyphenyl)-2-phenylethane-1,2-dione (0.01 mol, 2.70 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, and the mixture was heated to 90°C under nitrogen protection and refluxed for 1 h. After the reaction was completed as monitored by TCL, the mixture was cooled, washed with water until neutral, dried and recrystallized with ethanol to obtain 3.84 g of intermediate S4-1 with a yield of 86%.

[0057] Preparation of photoinitiator G4: Add 50 ml of toluene solution to a dry round-bottom flask, add intermediate S4-1 (7 mmol, 3.12 g), potassium ferrocyanide (70 mmol, 23.05 g), and 7.6 g of potassium hydroxide, stir and dissolve evenly, reflux for 5 h, and after TCL monitoring, separate the liquids after the reaction is complete, collect the organic phase, and spin dry to obtain 4.55 g of compound G4, with a yield of 73%. The molecular weight was determined by mass spectrometry (MALDI-TOF-MS) to be 890.758, which was determined to be the target compound G4.

[0058] Photoinitiator G5:

[0059]

[0060] Preparation of intermediate S5-1: 2-butoxy-5-nitrobenzaldehyde (0.01 mol, 2.23 g), aromatic aldehyde (0.01 mol, 2.10 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry 150 ml round-bottom flask, protected by nitrogen, heated to 90°C, and refluxed for 1 h. After the reaction was completed as monitored by TCL, it was cooled, washed with water to neutrality, dried, and recrystallized with ethanol to obtain 3.43 g of intermediate S5-1 with a yield of 83%.

[0061] Preparation of photoinitiator G5: Add 50 ml of toluene solution to a dry round-bottom flask, add intermediate S5-1 (7 mmol, 2.89 g), potassium ferrocyanide (70 mmol, 23.05 g), and 7.6 g of potassium hydroxide, stir and dissolve evenly, reflux for 5 h, monitor the reaction by TCL, separate the liquids, collect the organic phase, and spin dry to obtain 4.39 g of G5, with a yield of 76%. The molecular weight was determined by mass spectrometry (MALDI-TOF-MS) to be 824.597, which was confirmed to be the target compound G5.

[0062] Photoinitiator G6:

[0063]

[0064] Preparation of intermediate S6-1: 3,5-dinitrobenzaldehyde (0.01 mol, 1.96 g), 1-(2-chlorophenyl)-2-phenylethane-1,2-dione (0.01 mol, 2.45 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, protected by nitrogen, heated to 90°C, and refluxed for 1 h. After the reaction was completed as monitored by TCL, it was cooled, washed with water to neutrality, dried, and recrystallized with ethanol to obtain 3.58 g of intermediate S6-1 with a yield of 85%.

[0065] Preparation of intermediate S6-2: 4-ethoxybenzaldehyde (0.01 mol, 1.50 g), 1-(2-chlorophenyl)-2-phenylethane-1,2-dione (0.01 mol, 2.45 g), ammonium acetate (0.2 mol, 15.42 g) and 50 ml of acetic acid were added to a dry round-bottom flask, protected by nitrogen, heated to 90°C, and refluxed for 1 h. After the reaction was completed as monitored by TCL, it was cooled, washed with water to neutrality, dried, and recrystallized with ethanol to obtain 3.26 g of intermediate S6-2 with a yield of 87%.

[0066] Preparation of photoinitiator G6: Add 50 ml of toluene solution to a dry round-bottom flask, add intermediate S6-1 (3.5 mmol, 1.47 g), potassium ferrocyanide (70 mmol, 23.05 g), and 7.6 g of potassium hydroxide and stir to dissolve evenly, dissolve intermediate S6-2 (3.5 mmol, 1.31 g) in 50 ml of toluene solution, mix and stir the two solutions, reflux for 5 h, and after TCL monitoring the reaction is complete, separate the liquids, collect the organic phase, and spin dry to obtain 2.06 g of G6, with a yield of 74%. The molecular weight was determined by mass spectrometer (MALDI-TOF-MS) to be 792.913, which was determined to be the target compound G6.

[0067] Comparative Examples G7-G9 (commercially available):

[0068]

[0069] Example:

[0070] According to the formulation in Table 1 (Examples and Comparative Examples) below, the components were mixed in proportion and stirred thoroughly until they were completely dissolved to prepare a dry film photoresist composition.

[0071] Table 1

[0072]

[0073]

[0074] A1: cardo resin (trade name KBR series, manufactured by KISCO Co., Ltd.);

[0075] B1: dipentaerythritol hexaacrylate;

[0076] B2: bisphenol A dimethacrylate;

[0077] B3: Glycidyl acrylate;

[0078] D1: plasticizer, o-toluenesulfonamide;

[0079] D2: antioxidant, triphenyl phosphite;

[0080] D3: free radical stabilizer, p-methoxyphenol;

[0081] E1: Propylene glycol methyl ether acetate (PGMEA).

[0082] Performance testing:

[0083] Test sample preparation (film pasting - exposure - development):

[0084] Laminating: Polish the copper surface of the copper clad laminate with a grinder, wash with water, and dry to obtain a bright and fresh copper surface. Set the laminating machine roller temperature to 110°C, the conveying speed to 1.5m / min, and heat laminating under standard pressure.

[0085] Exposure: After film application, let the sample stand for more than 15 minutes and then use an exposure machine for exposure.

[0086] Development: After exposure, the sample was left to stand for more than 15 minutes, the development temperature was 30°C, and the pressure was 1.2Kg / cm 2 The developer is a 1%wt sodium carbonate aqueous solution, the developing time is 1.5-2.0 times the minimum developing time, and the film is washed with water and dried after development.

[0087] Performance testing:

[0088] Maximum absorption wavelength of photoinitiator: Weigh a certain amount of G1-G9 and dissolve it in dichloromethane to a concentration of 1×10 -5 mol / L solution, and measure the UV absorption spectrum of the solution at 25°C;

[0089] Sensitivity:

[0090] Preparation of photosensitive dry film: 200 ml of PGMEA and 1.5 g of azobisisobutyronitrile were placed in a 500 ml polymerization container, and acrylic acid monomers with 40 wt% solids were added in a molar ratio of 20:20:40:20 for methacrylic acid, glycidyl methacrylate, methyl methacrylate, and dicyclopentyl acrylate, and then stirred and polymerized at 70° C. for 5 hours under a nitrogen atmosphere to prepare an acrylic acid polymer. 50 wt% of acrylic acid polymer, 30 wt% of solvent, 5 wt% of the compound of the present invention as a photopolymerization initiator, 1.5 wt% of 2-mercaptobenzoxazole, and 0.5 wt% of colorless crystal violet were placed in a reaction mixing tank with a UV protective cover and a stirrer in sequence, and stirred at room temperature to prepare a photopolymerizable composition, which was filtered through a 100 mesh screen and evenly coated on a PET film with a coater, and the solvent was dried to prepare a photosensitive dry film with a film thickness of 30 μm, covered with a 23 μm thick polyethylene protective film, and placed at 25° C. for 8 hours;

[0091] The surface of the copper clad laminate was polished to remove the polyethylene protective film on the surface of the photosensitive dry film. The dry film resist was laminated on the copper clad laminate using a laminator at a speed of 1.2 m / min and a roller temperature of 105°C. The sensitivity was measured using a 41-level Stouffer exposure ruler. Twice the shortest developing time was used as the residence time in the developing machine chamber. The level that retains at least 50% of the photopolymer is the maintenance level, which is recorded as the sensitivity. The exposure energy required for a sensitivity of level 23 is the photosensitivity.

[0092] Adhesion: The photosensitive dry film photoresist composition obtained by Example 1-9 was laminated on a copper plate by hot pressing, and exposed using a mask having a wiring pattern with a width of n:400 (n is 5 to 25 μm) between the exposed part and the unexposed part. After development for 2.0 times the minimum development time, the minimum mask width at which a cured resist line is normally formed is taken as the adhesion value, and observed using a magnifying glass. The smaller the number read, the better the adhesion;

[0093] The test results are shown in Table 2 below:

[0094] Table 2

[0095]

[0096] As can be seen from the above table, by comparing Examples 1-6 with Examples 7-9, it can be found that Examples 1-6 obtain photosensitive photoinitiators, which, when used in photosensitive resin photoresist compositions, can effectively improve the photosensitivity, sensitivity, resolution, etc. of the photoresist.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A photoresist composition, characterized in that include: A photosensitive resin containing at least one ethylenically unsaturated group, an alkali-soluble resin, a photoinitiator, and an auxiliary agent; the photoinitiator is a photopolymerizable compound of a biimidazole structure, and its specific structure is shown in Formula 1: in: R1, R2, R3, R4, R5, and R6 are each independently selected from substituted or unsubstituted C 6-18 The aryl group is selected from C1-C 12 Alkyl, C1-C 12 At least one or more combinations of alkoxy, cyano, nitro and halogen; and at least one of R1, R3, R4 and R5 is selected from an aryl group in which m hydrogen atoms are replaced by R0, m≥2, and each R0 is the same or different and is selected from an alkoxy group or a nitro group.

2. The photoresist composition according to claim 1, characterized in that: The aryl group in which m hydrogen atoms are replaced by R0 has the structural formula shown in Formula 2: Wherein, * is the connection site, R7 is H or C1-C 12 Alkoxy, R8 is C1-C 12 Alkyl, C1-C 12 Alkoxy, cyano, nitro or halogen; the halogen is selected from Cl, Br; R7 is C3-C 10 When it is an alkoxy group, n≥1, and at least one of the R8 is an alkoxy group or a nitro group; when the R7 is H, n≥2, and at least two of the R8 are alkoxy groups or nitro groups.

3. The photoresist composition according to claim 2, characterized in that: The R1 and the R4 are both selected from the structural formula shown in Formula 2, and the R1 and the R4 are the same or different.

4. The photoresist composition according to claim 2, characterized in that: The R2 is the same as the R6, the R3 is the same as the R5, and the R2 is the same as or different from the R3.

5. The photoresist composition according to claim 1, characterized in that: The C 6-18 The aromatic group is selected from monocyclic aromatic hydrocarbons, condensed aromatic hydrocarbons, or a group consisting of any one or more of monocyclic aromatic hydrocarbons and condensed aromatic hydrocarbons.

6. The photoresist composition according to claim 1, characterized in that: The photosensitive resin includes resin oligomers and / or photopolymerizable monomers.

7. The photoresist composition according to claim 6, characterized in that: The photopolymerizable monomers include one or more polymerizable monomers having an aromatic group and / or an alicyclic hydrocarbon group and / or an alkane group.

8. The photoresist composition according to any one of claims 1 to 7, characterized in that: The auxiliary agent is selected from any one or more of a surfactant, a photoacid generator, an adhesion enhancer, a defoamer, a leveling agent, a plasticizer, an antioxidant, a stabilizer or an inhibitor.

9. A method for preparing a photoresist composition according to any one of claims 1 to 8, characterized in that: The method comprises at least the following steps: uniformly mixing the photosensitive resin, the alkali soluble resin, the photoinitiator and the auxiliary agent according to the weight ratio, filtering and degassing to obtain the photoresist composition.

10. A photosensitive dry film, comprising a support and a photosensitive layer, characterized in that: The photosensitive layer is formed from the photoresist composition according to any one of claims 1 to 8.

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