Photosensitive ink, curing method thereof and circuit board

Abstract

The invention provides photosensitive ink, a curing method thereof and a circuit board. The photosensitive ink comprises the following components in percentage by mass: 45-65% of epoxy acrylic resin; 20%-25% of epoxy resin; 0.5%-5% of a photoinitiator; 10%-30% of a reactive diluent; 0.5%-2% of black toner; and 1.5%-4.5% of an organic solvent. Wherein the photoinitiator is prepared from Irgacure OXE-01 and Irgacure OXE-02, and the photoinitiator is prepared from Irgacure OXE-01 and Irgacure The mass percent of the Irgacure OXE-01 in the photoinitiator is 10%-65%, and the mass percent of the Irgacure OXE-02 in the photoinitiator is 35%-90%. The photosensitive ink is obtained by mixing the resin, the oxime ester photoinitiator and other components in a specific proportion, and after exposure and curing are carried out under the conditions of specific wavelength, specific exposure quantity and exposure time under the assistance of a laser light source, a solder mask layer which is consistent in ink color and basically free of chromatic aberration (delta E is less than 1) can be obtained. According to the ink and the curing method thereof, the curing efficiency of the photosensitive ink is improved, and the production efficiency of a circuit board is improved.

Description

Technical Field

[0001] The present application relates to the technical field of circuit boards, and in particular to a photosensitive ink and a curing method thereof, and a circuit board. Background Art

[0002] The outer surface of the circuit board generally has a solder mask to protect the circuit board from external moisture or scratches. The formation principle of the solder mask is: the exposure wavelength emitted by the exposure light source reacts with the photoinitiator in the photosensitive ink to cause photothermal polymerization, so that the photosensitive ink is cured to form a pattern. After the uncured part is washed away by the developer, a pattern is formed on the surface of the circuit board. The composition of the photosensitive ink determines the properties of the photosensitive ink, and different types of photoinitiators require different exposure wavelengths.

[0003] The current photosensitive ink has the problem of inconsistent ink color. Although the inconsistent ink color problem of LED display screens can be solved by the mask process, it adds an extra process flow and the steps are cumbersome. Although the mask process can solve the problem of inconsistent ink color of the PCB light board of the SMD (surface mounted component) display screen, there are still problems such as reduced extended viewing angle, unacceptable side view, and uncontrollable warping of the mask. Summary of the invention

[0004] In view of this, the present application proposes a photosensitive ink that can solve the problem of inconsistent ink color.

[0005] In addition, it is also necessary to provide a curing method for curing the above-mentioned photosensitive ink and a circuit board.

[0006] An embodiment of the present application provides a photosensitive ink, which includes the following components by mass percentage:

[0007]

[0008] The photoinitiator includes 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime) and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone 1-(O-acetyl oxime). The mass percentage of the 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime) in the photoinitiator is 10% to 65%, and the mass percentage of the 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone 1-(O-acetyl oxime) in the photoinitiator is 35% to 90%.

[0009] In one embodiment, the reactive diluent includes one or more of acrylic monomers, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isobornyl (meth)acrylate, (2-ethyl-2-methyl-1,3-dioxolan-4-yl)acrylate, (2-isopropyl-2-methyl-1,3-dioxolan-4-yl)acrylate, glycidyl methacrylate.

[0010] In one embodiment, the organic solvent includes one or more of diethylene glycol monoethyl ether acetate, dimethyl phthalate, γ-butyrolactone, and methyl ethyl ketone.

[0011] In one embodiment, the organic solvent is diethylene glycol monoethyl ether acetate, dimethyl phthalate, γ-butyrolactone, and methyl ethyl ketone. The mass percentage of diethylene glycol monoethyl ether acetate in the photosensitive ink is 0.5% to 1.5%, the mass percentage of dimethyl phthalate in the photosensitive ink is 1% to 2%, the mass percentage of γ-butyrolactone in the photosensitive ink is less than 0.5%, and the mass percentage of methyl ethyl ketone in the photosensitive ink is less than 0.5%.

[0012] In one embodiment, the photosensitive ink further includes a filler, and the filler includes one or more of barium sulfate, silica, calcium carbonate, and kaolin.

[0013] In one embodiment, the filler is barium sulfate and silica. The mass percentage of barium sulfate in the photosensitive ink is 5% to 25%, and the mass percentage of silica in the photosensitive ink is 1% to 5%.

[0014] In one embodiment, the photosensitive ink further includes an additive. The mass percentage of the additive in the photosensitive ink is less than 0.1%, and the additive includes one or more of a dispersant, a leveling agent, and an antifoaming agent.

[0015] One embodiment of the present application provides a curing method for a photosensitive ink, and the photosensitive ink is the photosensitive ink as described above. The curing method includes: exposing the photosensitive ink to a light source that emits light with a first wavelength and a second wavelength, the first wavelength is 320 nm to 385 nm, the second wavelength is 365 nm to 420 nm, the exposure dose is 600 mj / cm 2 ~1050 mj / cm 2 , and the exposure time is 65 s to 100 s.

[0016] In one embodiment, the light source is a laser light source.

[0017] An embodiment of the present application provides a circuit board, which includes a solder mask layer. The solder mask layer is cured from the photosensitive ink as described above by the curing method as described above.

[0018] The photosensitive ink of the present application is obtained by mixing resin, oxime ester photoinitiator and other components in a specific ratio. After being exposed and cured with a laser light source at a specific wavelength, specific exposure amount and exposure time, a solder mask layer with consistent ink color and basically no color difference (ΔE < 1) can be obtained. The ink and its curing method of the present application improve the curing efficiency of the photosensitive ink, which is beneficial to improving the production efficiency of the circuit board. The ink and its curing method of the present application can effectively improve the color uniformity of the solder mask layer and reduce the color difference (ΔE). Therefore, the LED packaging process can be changed from the original black fog glue packaging to transparent glue packaging, which is beneficial to improving the brightness of LED products. Description of the Drawings

[0019] Figure 1 It is a cross-sectional view of the circuit board provided by an embodiment of the present application.

[0020] Figure 2 It is a graph of the color difference values (ΔE) of the photosensitive inks of Example 1 and Comparative Examples 1-2 of the present application.

[0021] Description of the Main Component Symbols

[0022] Circuit board 100

[0023] Dielectric layer 10

[0024] Conductive circuit layer 20

[0025] Solder mask layer 30

[0026] The following specific embodiments will further illustrate the embodiments of the present application in conjunction with the above drawings. Specific Embodiments

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the embodiments of the present application belong. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application.

[0028] It will be understood that when a layer is referred to as being "on" another layer, it can be directly on the other layer or there can be an intermediate layer therebetween. In contrast, when a layer is referred to as being "directly on" another layer, there is no intermediate layer.

[0029] Embodiments of the present application are described with reference to cross-sectional views, which are schematic diagrams of idealized embodiments (and intermediate configurations) of the present application. Thus, differences in the shapes shown due to manufacturing processes and / or tolerances are foreseeable. Therefore, the embodiments of the present application should not be construed as limited to the specific shapes of the regions shown herein, but should include, for example, deviations in shape resulting from manufacturing. The regions shown in the figures are themselves merely schematic, their shapes are not intended to illustrate the actual shape of the device, and are not intended to limit the scope of the present application.

[0030] A first aspect of the present application provides a photosensitive ink, which can be used to form a solder mask layer on the surface of a circuit board to protect the circuit board from external moisture invasion or foreign object scratching, etc. The photosensitive ink includes the following components by mass percentage: 45% - 65% of epoxy acrylate resin; 20% - 25% of epoxy resin; 0.5% - 5% of photoinitiator; 10% - 30% of reactive diluent; 0.5% - 2% of black toner; 1.5% - 4.5% of organic solvent. Among them, the photoinitiator includes 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime) and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone 1-(O-acetyl oxime). The mass percentage of 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime) in the photoinitiator is 10% - 65%, and the mass percentage of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone 1-(O-acetyl oxime) in the photoinitiator is 35% - 90%.

[0031] As the main components of the photosensitive ink, epoxy acrylate resin and epoxy resin can undergo a curing reaction to form a protective layer (solder mask layer) of the circuit board. The contents of epoxy acrylate resin and epoxy resin are 45% - 65% and 20% - 25% respectively. If the contents of epoxy acrylate resin and epoxy resin are too high, the viscosity of the photosensitive ink will be too large, affecting its use; if the contents of epoxy acrylate resin and epoxy resin are too low, the heat resistance and electroplating resistance of the photosensitive ink after curing will be affected. The content of epoxy acrylate resin can be 45%, 46%, 50%, 52%, 55%, 56%, 60%, 65%, etc., which will not be listed one by one here. The content of epoxy resin can be 20%, 21%, 22%, 22.5%, 23%, 24%, 24.5%, 25%, etc., which will not be listed one by one here.

[0032] The photoinitiator of the present application is an oxime ester photoinitiator. The oxime ester photoinitiator undergoes type I cleavage of the N-O bond at the γ position (rapid cleavage between the N-O bonds, also known as γ-scission), forming an oxime radical, which is the main initiator for the polymerization (curing) reaction of the resin. 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime) is called photoinitiator Irgacure OXE-01 (BASF, Germany), and its molecular formula is C 27 H 27 NO 3 S, with a CAS number of 253585-83-0, and the structural formula is The absorption peak of Irgacure OXE-01 is 327 nm, it does not yellow, and it is a highly efficient radical photoinitiator for near-ultraviolet light, which can be used in color filters, resins for black substrates, and other display applications. 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone 1-(O-acetyl oxime) is called photoinitiator Irgacure OXE-02 (BASF, Germany), and its molecular formula is C 26 H 24 N 2 O 3 , with a CAS number of 478556-66-0, and the structural formula is The absorption peak of Irgacure OXE-02 is 375 nm, with only slight yellowing, and it is a highly efficient radical photoinitiator for near-ultraviolet light, which can be used in color filters, resins for black substrates, and other display applications. The Irgacure OXE series of photoinitiators have their substituents specifically designed to absorb longer wavelengths of near-ultraviolet light and are suitable for applications in resin inks for black substrates. The proportion of Irgacure OXE-01 in the photoinitiator is 10% - 65%, and the proportion of Irgacure OXE-02 in the photoinitiator is 35% - 90%. The photoinitiators mixed within the above proportion ranges are more conducive to strengthening the integrity of the bottom layer exposure reaction of the photosensitive ink. The proportion of Irgacure OXE-01 in the photoinitiator can be 10%, 20%, 22%, 25%, 30%, 40%, 50%, 60%, 65%, etc., which are not listed one by one here. The proportion of Irgacure OXE-02 in the photoinitiator can be 35%, 38%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, etc., which are not listed one by one here.

[0033] The reactive diluent can participate in the curing reaction of the resin and become a part of the crosslinked network structure of the cured product, while also reducing the viscosity of the system. The content of the reactive diluent is 10% - 30%. If the content of the reactive diluent is too high, it is likely to reduce the rate of the curing reaction and prolong the reaction time. If the content of the reactive diluent is too low, the viscosity of the photosensitive ink may be too high. Specifically, the content of the reactive diluent can be 10%, 12%, 15%, 18%, 20%, 21%, 25%, 30%, etc., and will not be listed one by one here.

[0034] In some embodiments, the reactive diluent can be, but is not limited to, one or more of acrylic monomers, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isobornyl (meth)acrylate, (2-ethyl-2-methyl-1,3-dioxolane-4-yl)acrylate, (2-isopropyl-2-methyl-1,3-dioxolane-4-yl)acrylate, glycidyl methacrylate, etc.

[0035] The black toner makes the photosensitive ink present black (ink color), and the black toner can be obtained by commercial purchase. This application does not limit the manufacturer of the black toner.

[0036] In some embodiments, the organic solvent can be, but is not limited to, one or more of diethylene glycol monoethyl ether acetate, dimethyl adipate (DBE), γ-butyrolactone, and methyl ethyl ketone.

[0037] Furthermore, the organic solvent is diethylene glycol monoethyl ether acetate, dimethyl adipate, γ-butyrolactone, and methyl ethyl ketone. The mass percentage of diethylene glycol monoethyl ether acetate in the photosensitive ink is 0.5% - 1.5%. For example, the content of diethylene glycol monoethyl ether acetate can be 0.5%, 0.55%, 0.8%, 1.0%, 1.5%, etc., and will not be listed one by one here. The mass percentage of dimethyl adipate in the photosensitive ink is 1% - 2%. For example, the content of dimethyl adipate can be 1%, 1.3%, 1.5%, 1.8%, 2%, etc., and will not be listed one by one here. The mass percentage of γ-butyrolactone in the photosensitive ink is less than 0.5%, and the mass percentage of methyl ethyl ketone in the photosensitive ink is less than 0.5%.

[0038] In some embodiments, the photosensitive ink further includes a filler. The filler can be, but is not limited to, one or more of barium sulfate, silica, calcium carbonate, and kaolin. The addition of the filler is beneficial to the interaction of each component, making the arrangement of each component more uniform and compact, thereby improving the film hardness of the photosensitive ink, maintaining the gloss of the photosensitive ink, and enhancing its heat resistance. The particle size of the filler can be 1000 mesh - 1500 mesh.

[0039] Further, the fillers are barium sulfate and silicon dioxide. The mass percentage of barium sulfate in the photosensitive ink is 5% to 25%, for example, the content of barium sulfate can be 5%, 6%, 7%, 10%, 15%, 20%, 25%, etc., which are not listed here. The mass percentage of silicon dioxide in the photosensitive ink is 1% to 5%, for example, the content of silicon dioxide can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 5%, etc., which are not listed here.

[0040] In some embodiments, the photosensitive ink further includes an additive, which accounts for less than 0.1% of the mass percentage of the photosensitive ink. The additive may be, but is not limited to, one or more of a dispersant, a leveling agent, and a defoamer. The dispersant may be, but is not limited to, sodium oleate, polyacrylate, aminopropylamine dioleate, octadeceneamine acetate, etc. The leveling agent may be, but is not limited to, silicone acrylate, polyorganosiloxane, isopropyl alcohol, polyvinyl butyral, etc. The defoamer may be, but is not limited to, polyether fatty alcohol polyether, polydimethylsiloxane, polyoxyethylene oxypropylene glycerol, etc.

[0041] The second aspect of the present application provides a method for curing the above-mentioned photosensitive ink: exposing the photosensitive ink to a light source, the light source emits light with a first wavelength and a second wavelength, the first wavelength is 320nm to 385nm, the second wavelength is 365nm to 420nm, and the exposure amount is 600mj / cm 2 ~1050mj / cm 2 , the exposure time is 65s~100s.

[0042] Furthermore, the light source is a laser light source.

[0043] See also Figure 1 In a third aspect, the present application provides a circuit board 100, which can be a hard board, a flexible board (FPC), a hard-soft board, etc., and can also be a single-layer board or a multi-layer board, which is not limited by the present application. Figure 1 As shown, the circuit board 100 includes at least one dielectric layer 10 and at least one conductive circuit layer 20. If there are multiple conductive circuit layers 20, each dielectric layer 10 is disposed between two adjacent conductive circuit layers 20. The two adjacent conductive circuit layers 20 can be electrically connected through a conductive structure (not shown). Figure 1 The circuit board 100 including one dielectric layer 10 and two conductive circuit layers 20 is only exemplarily shown. In other embodiments, the number of conductive circuit layers 20 may be increased.

[0044] The solder mask layer 30 can be disposed on the surface of the outermost conductive circuit layer 20, and the solder mask layer 30 is formed by curing the above-mentioned photosensitive ink through the above-mentioned curing method. Specifically, the above-mentioned photosensitive ink is printed on the surface of the outermost conductive circuit layer 20, and then exposed and cured under a laser light source. The laser light source emits light with a first wavelength and a second wavelength. The first wavelength is 320nm - 385nm, and the second wavelength is 365nm - 420nm. The light with the first wavelength and the light with the second wavelength simultaneously cure the photosensitive ink, and the total exposure amount of the two is 600mj / cm 2 ~1050mj / cm 2 , and the exposure time is 65s - 100s. After curing is completed, the circuit board 100 can be rinsed with sodium carbonate solution to dissolve the photosensitive ink that has not been exposed to light and cured (i.e., the developing step), and the solder mask layer 30 is obtained.

[0045] In some embodiments, the material of the dielectric layer 10 can be, but is not limited to, one of polyimide, polypropylene, liquid crystal polymer, polyether ether ketone, polyethylene terephthalate, and polyethylene naphthalate. The material of the conductive circuit layer 20 can be, but is not limited to, copper, gold, silver, etc. In this embodiment, the material of the dielectric layer 10 is polyimide, and the material of the conductive circuit layer 20 is copper.

[0046] The present application will be further described below in conjunction with specific embodiments and comparative examples.

[0047] Example 1

[0048] In this embodiment, the components and their contents of the photosensitive ink are: epoxy acrylate resin 45%, epoxy resin 25%, photoinitiator 0.5% (wherein, the mass percentage of Irgacure OXE - 01 in the total photoinitiator is 35%, and the mass percentage of Irgacure OXE - 02 in the total photoinitiator is 65%), acrylic monomer (reactive diluent) 20%, black toner 1.5%, diethylene glycol monoethyl ether acetate (organic solvent) 0.5%, dimethyl phthalate (organic solvent) 1%, γ - butyrolactone (organic solvent) 0.22%, methyl ethyl ketone (organic solvent) 0.2%, barium sulfate (filler) 5%, silicon dioxide (filler) 1%, sodium oleate (dispersant) 0.08%.

[0049] The photosensitive ink of Example 1 was printed on the outer surface of the circuit board and then exposed by a laser light source. The laser light source emits light with a first wavelength and a second wavelength. The first wavelength is 320nm - 385nm, and the second wavelength is 365nm - 420nm. The light with the first wavelength and the light with the second wavelength simultaneously expose and cure the photosensitive ink, and the total exposure amount of the two is 600mj / cm 2 ~1050mj / cm 2, wherein the exposure amount of the first wavelength accounts for 15% to 45%, the exposure amount of the second wavelength accounts for 55% to 85%, and the exposure time is 65s to 100s. Finally, after the development step (using sodium carbonate solution to remove the uncured photosensitive ink that has not seen light), the solder mask is obtained.

[0050] The L, a, and b values ​​of the solder mask surface can be measured using a spectrophotometer, and ΔE can be calculated using the formula: ΔE = [(ΔL) 2 +(Δa) 2 +(Δb) 2 )] 0.5 . Among them, ΔL, Δa, and Δb represent the differences between the three chromaticity values ​​of L, a, and b respectively. When ΔE is in the range of 0 to 1, it means that the colors cannot be distinguished. When ΔE is in the range of 1 to 3, it means that the colors are slightly different. When ΔE is in the range of 4 to 7, it means that the colors are significantly different. When ΔE>8, it means that the colors are significantly different.

[0051] like Figure 2 As shown, the color difference value ΔE of the solder mask in Example 1 is 0.478-0.612, indicating that the color of the solder mask is consistent everywhere, there is basically no color difference, and the difference cannot be distinguished, which effectively improves the problem of inconsistent ink color of the solder mask.

[0052] Comparative Example 1

[0053] The photosensitive ink of Comparative Example 1 is consistent with the photosensitive ink of Example 1, and the main difference lies in the difference in exposure (curing) method.

[0054] The photosensitive ink of comparative example 1 is printed on the outer surface of the circuit board and then exposed by an LED light source. There are two LED light sources, one of which emits light with a wavelength of 360nm to 370nm, and the exposure amount is 700 to 1150mj / cm 2 Another LED light source emits light having a first wavelength and a second wavelength, the first wavelength is 395nm-410nm, the second wavelength is 420nm-445nm, and the total exposure of the two is 600mj / cm 2 ~1050mj / cm 2 (The exposure amount of the first wavelength accounts for 35% to 50%, and the exposure amount of the second wavelength accounts for 50% to 65%). The three wavelengths of light are simultaneously exposed to cure the photosensitive ink, and the exposure time is 65s to 100s. After the development step (using sodium carbonate solution to remove the uncured photosensitive ink that has not been exposed to light), the solder mask is obtained.

[0055] The color difference value ΔE of the solder mask in Comparative Example 1 was tested using a colorimeter. Figure 2As shown, the color difference value ΔE of the solder mask in Comparative Example 1 is 1.289 to 1.456, indicating that there are slight differences in the colors of different parts of the solder mask.

[0056] Comparative Example 2

[0057] The photosensitive ink in Comparative Example 2 is the same as the photosensitive ink in Example 1, and the main difference lies in the difference in the exposure (curing) method.

[0058] Print the photosensitive ink of Comparative Example 2 on the outer surface of the circuit board and then expose it with a UV light source. Among them, the exposure wavelength of the UV light source is 10 nm to 600 nm, the exposure dose is 900 to 1350 mj / cm 2 , and the exposure time is 185 s to 430 s. After the development step (removing the unexposed and uncured photosensitive ink with sodium carbonate solution), a solder mask is obtained.

[0059] Use a color difference meter to measure the color difference value ΔE of the solder mask in Comparative Example 2. As Figure 2 shown, the color difference value ΔE of the solder mask in Comparative Example 2 is 2.851 to 3.205, indicating that there are slight differences in the colors of different parts of the solder mask.

[0060] The photosensitive ink described in this application is obtained by mixing resin, oxime ester type photoinitiator and other components in a specific ratio. After being exposed and cured with a laser light source at a specific wavelength, specific exposure dose and exposure time, a solder mask with consistent ink color and basically no color difference (ΔE < 1) can be obtained. The ink and its curing method described in this application improve the curing efficiency of the photosensitive ink and are beneficial to improving the production efficiency of the circuit board. The ink and its curing method described in this application can effectively improve the color uniformity of the solder mask and reduce the color difference (ΔE). Therefore, the LED packaging process can be changed from the original black fog glue packaging to transparent glue packaging, which is beneficial to improving the brightness of LED products.

[0061] The above description is some specific embodiments of this application, but in actual application, it cannot be limited to these embodiments only. For those of ordinary skill in the art, other deformations and changes made according to the technical concept of this application should fall within the protection scope of this application.

Claims

1. A photosensitive ink, characterized in that, it comprises the following components by mass percentage: Among them, the photoinitiator includes 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime) and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone 1-(O-acetoxime), and the mass percentage of 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime) in the photoinitiator is 10% - 65%, and the mass percentage of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone 1-(O-acetoxime) in the photoinitiator is 35% - 90%.

2. The photosensitive ink according to claim 1, characterized in that, the active diluent includes one or more of acrylic monomers, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isobornyl (meth)acrylate, (2-ethyl-2-methyl-1,3-dioxolan-4-yl)acrylate, (2-isopropyl-2-methyl-1,3-dioxolan-4-yl)acrylate, glycidyl methacrylate.

3. The photosensitive ink according to claim 1, characterized in that, the organic solvent includes one or more of diethylene glycol monoethyl ether acetate, dimethyl phthalate, γ-butyrolactone, methyl ethyl ketone.

4. The photosensitive ink according to claim 3, characterized in that, the organic solvent is diethylene glycol monoethyl ether acetate, dimethyl phthalate, γ-butyrolactone and methyl ethyl ketone, the mass percentage of diethylene glycol monoethyl ether acetate in the photosensitive ink is 0.5% - 1.5%, the mass percentage of dimethyl phthalate in the photosensitive ink is 1% - 2%, the mass percentage of γ-butyrolactone in the photosensitive ink is less than 0.5%, and the mass percentage of methyl ethyl ketone in the photosensitive ink is less than 0.5%.

5. The photosensitive ink according to claim 1, characterized in that, the photosensitive ink further includes a filler, and the filler includes one or more of barium sulfate, silica, calcium carbonate, kaolin.

6. The photosensitive ink according to claim 5, characterized in that, the filler is barium sulfate and silica, the mass percentage of barium sulfate in the photosensitive ink is 5% - 25%, and the mass percentage of silica in the photosensitive ink is 1% - 5%.

7. The photosensitive ink according to claim 1, characterized in that, the photosensitive ink further includes an additive, the mass percentage of the additive in the photosensitive ink is less than 0.1%, and the additive includes one or more of a dispersant, a leveling agent, an antifoaming agent.

8. A curing method for a photosensitive ink, characterized in that, The photosensitive ink is the photosensitive ink described in any one of claims 1 to 7. The curing method includes: exposing the photosensitive ink to a light source that emits light with a first wavelength and a second wavelength, where the first wavelength is 320 nm to 385 nm, the second wavelength is 365 nm to 420 nm, and the exposure dose is 600 mj / cm 2 ~1050 mj / cm 2 , and the exposure time is 65 s to 100 s.

9. The curing method according to claim 8, characterized in that, the light source is a laser light source.

10. A circuit board, characterized in that, it includes a solder mask layer, and the solder mask layer is cured from the photosensitive ink according to any one of claims 1 - 7 by using the curing method according to claim 8 or 9.

Images