Fluorenyl magnolol light-cured solder resist ink and preparation method thereof

Abstract

The invention provides fluorenyl magnolol light-cured solder resist ink and a preparation method thereof, the solder resist ink comprises the following raw material components by mass: 20%-60% of fluorenyl magnolol light-cured resin, 10%-25% of a reactive diluent, 10%-30% of a nano filler, 1%-5% of a photoinitiator, 0.1%-5% of an auxiliary agent, and the balance of a solvent, the fluorenyl magnolol light-cured resin is prepared by reacting 9-fluorenylidene acetic acid with thionyl chloride to generate an intermediate product fluorenyl anhydride, and then reacting the intermediate product fluorenyl anhydride with magnolol. Wherein the molar ratio of magnolol to thionyl chloride to 9-fluorenylidene acetic acid is 1: (2-4): (2-4). The preparation process is simple, toxic by-products are avoided, the prepared solder resist ink has excellent flame retardance, heat resistance and adhesive force, low dielectric constant and high hardness, the problems of high dielectric loss, insufficient flame retardance and BPA toxicity of traditional ink are solved, and the solder resist ink is completely suitable for production and manufacturing of PCB substrates for high-frequency communication.

Description

[Technical Field]

[0001] This invention belongs to the technical field of high-frequency and high-speed electronic circuit packaging materials, specifically relating to a fluorene-based honokiol photocurable solder resist ink and its preparation method. It is suitable for surface insulation protection of circuit boards in high-frequency scenarios such as 5G communication and satellite navigation, and has low dielectric constant, high heat resistance and excellent photocuring performance. [Background Technology]

[0002] A printed circuit board (PCB) is an important electronic component that provides electrical connections for electronic devices. It acts like the "skeleton" and "nervous system" of an electronic product, providing a platform for fixing and connecting various electronic components, enabling them to interconnect according to design requirements and achieve specific circuit functions. The process mainly includes three stages: design, manufacturing, and assembly. First, computer-aided design software is used to design the PCB, determining the circuit pattern and component layout. Then, using photolithography and etching methods, the circuit pattern is transferred to an insulating substrate, and conductive lines are formed through processes such as drilling and copper plating. Finally, various electronic components are soldered onto the PCB to complete the assembly. Its applications are extremely wide, covering consumer electronics (such as mobile phones, computers, and televisions), communication equipment (such as base stations and routers), industrial control, medical instruments, aerospace, and many other fields.

[0003] Solder resist ink is a special ink used in the soldering process of printed circuit boards. Its main function is to prevent physical breaks in the conductor circuit, avoid short circuits caused by bridging during the soldering process, and ensure that solder is only applied to the necessary parts, reducing solder waste. With the rapid development of technology and the high-frequency and high-speed fields, the requirements for solder resist ink are gradually developing towards low dielectric constant, low dielectric loss, high flame retardancy, and high Tg. Currently, the main way to improve the flame retardancy of traditional solder resist inks is by adding flame retardants (such as aluminum hydroxide and brominated flame retardants), which has significant drawbacks. Additive flame retardants are prone to migration and volatilization, leading to a decrease in flame retardant function. Moreover, the addition amount needs to exceed 30% to meet the basic flame retardant requirements, which seriously affects the film-forming properties and mechanical properties of the ink. Traditional epoxy acrylate solder resist inks have a high dielectric constant (Dk≈3.5-4.0) due to their strong molecular chain polarity (containing polar groups such as hydroxyl and ether bonds). At high frequencies of 10GHz, the dielectric loss (Df>0.005) is significant, leading to signal distortion. At the same time, their heat resistance is insufficient (Tg≈150℃), making them unable to withstand multiple soldering processes in high-density packaging.

[0004] Epoxy resins (EPs) are important thermosetting polymers with excellent properties such as strong adhesion, good mechanical properties, high electrical insulation, and good chemical resistance. As matrix resins in composite materials, EPs are widely used in construction, coatings, machinery, and instruments. However, unfortunately, almost all commercially available epoxy resins are derived from non-renewable petroleum resources, with over 90% being bisphenol A (BPA) epoxy resins. The two main reactive monomers are BPA and epichlorohydrin. Although epichlorohydrin can be commercially produced from bio-based glycerol, BPA remains entirely dependent on petroleum resources, and its molar mass accounts for over 67% of the total BPA epoxy resin content. Furthermore, BPA, as an endocrine disruptor, has been classified as a reproductive toxicity R2 substance, posing a significant threat to human health. Based on these energy and health concerns, developing sustainable and non-toxic biomass resources to replace BPA in the preparation of bio-based epoxy resins has become a research hotspot.

[0005] Magnolol is a bioactive compound extracted from the bark of the magnolia tree. It is commonly used as an ingredient in herbal medicine and cosmetics and has been proven to be a safe substance with extremely low side effects. Notably, it is also a highly attractive multifunctional bio-based monomer, naturally containing symmetrical bisphenol groups and diallyl structures within its molecule, making it ideal for synthesizing various bio-based polymers. The allyl group, as an active group, has been widely used to increase polymer crosslinking density and improve processing performance. Furthermore, the biphenyl structure in magnool is a highly aromatic group; introducing it into polymer systems not only enhances thermal stability but also forms a highly pyrolysis-resistant carbon layer during combustion, thus significantly improving the flame retardancy of the material.

[0006] Fluorene is a rigid planar polycyclic aromatic hydrocarbon formed by two benzene rings bridged by a methylene group. Its conjugated structure endows the molecule with low polarity and high stability, while the high reactivity of the carbon atom at position 9 allows for the introduction of functional groups such as epoxy groups and acrylates. Introducing fluorene structures into resins can significantly reduce the dielectric constant, suppress dielectric loss, and enhance high-temperature stability. These properties make it a key material in fields such as 5G communication and high-frequency substrates.

[0007] Currently, the main methods for preparing solder resist inks are as follows:

[0008] Chinese patent CN202411486159.9 discloses an LDI solder resist ink and its preparation method. The raw materials include the following components: carboxylic acid-modified carboxyl-polycaprolactone acrylate epoxy resin, inorganic fillers, photoinitiators, and additives. The carboxylic acid-modified carboxyl-polycaprolactone acrylate epoxy resin is prepared by adding carboxyl-polycaprolactone acrylate and acrylic acid to an epoxy resin modification solution, followed by uniform dispersion and grinding to obtain the finished product. This patent proposes using carboxylic acid-modified carboxyl-polycaprolactone acrylate epoxy resin as the core resin and, by optimizing the ratio of inorganic fillers, photoinitiators, and additives, solves the problem of long exposure time and slow curing speed caused by incompatibility between traditional LDI solder resist inks and exposure machines. However, there is still room for improvement in terms of high-temperature stability, environmental friendliness, and process compatibility.

[0009] Chinese patent CN202510189817.6 discloses a flame-retardant PBT / brominated polycarbonate composition, comprising the following components by weight: 40-60 parts PBT; 30-50 parts brominated polycarbonate; 0.2-0.5 parts anti-dripping agent; and 10-15 parts glycidyl methacrylate grafted toughening agent. The viscosity-average molecular weight of the brominated PC is 13,000-30,000, and the molar ratio of bisphenol A to tetrabromobisphenol A is 55-40:45-60. It proposes the use of a UV-curable halogen-free flame retardant. While this patent addresses the flame retardancy issues of solder resist inks to some extent, it does not consider the long-term effectiveness of solder resist inks.

[0010] Therefore, although the existing solder resist inks on the market can improve flame retardancy to a certain extent, they still have problems such as high dielectric constant, complex process, and poor flexibility. There is an urgent need for an improved photocurable solder resist ink that has low dielectric constant, high glass transition temperature, simple synthesis, safety and environmental protection, and hardness. [Summary of the Invention]

[0011] One of the technical problems to be solved by the present invention is to provide a fluorenyl magnolol photocurable solder resist ink, which contains a fluorenyl magnolol resin component and has excellent flame retardant properties, heat resistance, adhesion, low dielectric constant and high hardness, thus solving the problems of high dielectric loss, insufficient flame retardancy and BPA toxicity of traditional inks.

[0012] The present invention achieves one of the above-mentioned technical problems in the following way:

[0013] A fluorenyl magnolol photocurable solder resist ink comprises the following raw material components by weight: 20%-60% fluorenyl magnolol photocurable resin, 10%-25% reactive diluent, 10%-30% nanofiller, 1%-5% photoinitiator, 0.1%-5% additives, and the balance being solvent.

[0014] Furthermore, the fluorenyl honokiol photocurable resin is prepared by reacting 9-fluoreneylic acid with thionyl chloride, and then reacting the intermediate product fluoreneic anhydride with honokiol; wherein the molar ratio of honokiol, thionyl chloride and 9-fluoreneylic acid is 1:2-4:2-4.

[0015] Furthermore, the structural formula of the fluorenyl honokiol photocurable resin is shown in formula (I) below:

[0016]

[0017] Furthermore, the content of the fluorenyl honokiol photocurable resin is 60%; the content of the reactive diluent is 15%; the content of the nanofiller is 20%; and the content of the photoinitiator is 2%.

[0018] Furthermore, the reactive diluent is one or more of tripropylene glycol diacrylate, trimethylolpropane triacrylate, β-hydroxyethyl methacrylate, and pentaerythritol triacrylate;

[0019] The nanofiller is one or more of silica powder, talc powder, fumed silica, and barium sulfate;

[0020] The photoinitiator is one or more of 2-ethylanthraquinone, benzoin diethyl ether 651, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone;

[0021] The additives include leveling agents and defoamers. The leveling agent is an organosilicon compound with a content of 0.5%-2%, and the defoamer is polyoxyethylene-polyoxypropylene block copolymer L62 with a content of 0.5%-2%. The ratio of leveling agent to defoamer is 7:3, with leveling agent as the main component.

[0022] The solvent is at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate.

[0023] Furthermore, the leveling agent content is 1.4%, and the defoamer content is 0.6%.

[0024] The second technical problem to be solved by the present invention is to provide a method for preparing fluorene-based magnolol photocurable solder resist ink. The preparation process is simple, has no toxic byproducts, and the prepared solder resist ink has excellent flame retardant properties, heat resistance, adhesion, low dielectric constant and high hardness.

[0025] The present invention achieves the second technical problem mentioned above in the following way.

[0026] A method for preparing a fluorene-based honokiol photocurable solder resist ink, the method comprising the following steps:

[0027] S1: Mix the fluorenyl honokiol photocurable resin with the solvent and stir at a speed of 1300-1800 r / min for a while;

[0028] S2: Add photoinitiator and nanofiller, and stir at 1300-1800r / min until uniform;

[0029] S3: Grind the mixed material in step S2 to a fineness of less than 8μm, and then add the additives and mix evenly;

[0030] S4: Adjust the viscosity to 500±50 Pa·s with an active diluent, and filter to obtain the finished product.

[0031] Furthermore, the preparation method of the fluorenyl honokiol photocurable resin includes the following steps:

[0032] (1) Dissolve 9-fluoreneacetic acid in an organic solvent, slowly add thionyl chloride dropwise under stirring, heat the mixture to 60-80℃, and react for 4-8 hours; after the reaction is complete, recrystallize with organic solvent, filter, and wash the filtrate with distilled water several times; then separate and dry the combined organic layers with anhydrous Na2SO4, concentrate the dried organic layers under vacuum, and dry them in a vacuum oven at 60℃ to finally obtain 9-fluoreneacetic anhydride;

[0033] (2) Add 9-fluorene-based acetic anhydride and magnolol to a flask, add sulfuric acid as a catalyst, stir at 70°C for 8 hours to obtain fluorene-based magnolol photocurable resin.

[0034] Furthermore, in step (1), the organic solvent includes at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate.

[0035] The molar ratio of magnolol, 9-fluoreneacetic acid and thionyl chloride monomer is 1:2-4:2-4.

[0036] Furthermore, the molar ratio of 9-fluoreneacetic anhydride to magnolol monomer is 1:1-1.2.

[0037] The present invention has the following advantages:

[0038] The solder resist ink of this invention contains fluorene-based honokiol resin, which is prepared by reacting 9-fluoreneacetic acid with thionyl chloride to obtain fluorene anhydride, and then reacting the intermediate fluorene anhydride with honokiol. This resin has a high fluorene content, exhibiting low dielectric constant and flame retardant properties. The double bonds it contains can participate in ink curing and will not lose their flame retardant function due to migration or volatilization, achieving long-term flame retardancy. Furthermore, as a reactive flame retardant, it does not affect the overall performance of the ink itself. The flame retardant synthesis method is simple, requires minimal experimental conditions, has low viscosity, and exhibits good processability. Therefore, the solder resist ink prepared by this invention possesses excellent flame retardant properties, heat resistance, adhesion, low dielectric constant, and high hardness.

[0039] This invention is based on magnolol fluorenyl derivatives and uses magnolol from biomass as a raw material for preparation. It can reduce the dependence of existing resins on petrochemical resources and their pollution to the environment. It is a bio-based, green and environmentally friendly product with the dual benefits of saving petroleum resources and protecting the environment.

[0040] The preparation method of this invention is relatively simple, with a high degree of reaction at each step and minimal impact from side reactions, thereby improving the overall quality of the product. This invention generates no waste during the preparation process, requires convenient or no post-processing, and makes the production process simple and efficient.

Detailed Implementation Methods

[0041] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] It should be clarified that the embodiments listed herein are merely illustrative examples of the technical solutions of the present invention, and not an exhaustive limitation on the scope of protection. Based on the general understanding of the prior art by those skilled in the art, any technical solutions derived from parameter adjustments, component substitutions, or process optimizations of the embodiments through conventional experimental methods without departing from the core concept of the present invention are all considered to fall within the scope of protection of the claims of the present invention. Unless otherwise expressly defined, the technical terms used herein shall be interpreted according to their common meaning in the art; if the same term has multiple interpretations, the meaning defined in the context of this specification shall prevail.

[0043] This invention relates to a fluorene-based magnolol photocurable solder resist ink, comprising the following raw material components by weight: 20%-60% fluorene-based magnolol photocurable resin, 10%-25% reactive diluent, 10%-30% nanofiller, 1%-5% photoinitiator, 0.1%-5% additives, and the balance being solvent.

[0044] In some embodiments, the fluorenyl honokiol photocurable resin is prepared by reacting 9-fluoreneylacetic acid with thionyl chloride, and then reacting the intermediate product fluoreneic anhydride with honokiol; wherein the molar ratio of honokiol, thionyl chloride and 9-fluoreneylacetic acid is 1:2-4:2-4.

[0045] In some embodiments, the fluorene-based honokiol photocurable resin has the following structural formula (I):

[0046]

[0047] In some embodiments, the content of the fluorenyl honokiol photocurable resin is 60%; the content of the reactive diluent is 15%; the content of the nanofiller is 20%; and the content of the photoinitiator is 2%.

[0048] In some embodiments, the reactive diluent is one or more of tripropylene glycol diacrylate, trimethylolpropane triacrylate, β-hydroxyethyl methacrylate, and pentaerythritol triacrylate;

[0049] The nanofiller is one or more of silica powder, talc powder, fumed silica, and barium sulfate;

[0050] The photoinitiator is one or more of 2-ethylanthraquinone, benzoin diethyl ether 651, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone;

[0051] The additives include leveling agents and defoamers, wherein the leveling agent is an organosilicon compound with a content of 0.5%-2%, and the defoamer is polyoxyethylene-polyoxypropylene block copolymer L62 with a content of 0.5%-2%. The ratio of leveling agent to defoamer is 7:3, with leveling agent as the main component.

[0052] The solvent is at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate.

[0053] In the following embodiments, the leveling agent content is 1.4% and the defoamer content is 0.6%.

[0054] This invention also relates to a method for preparing the aforementioned fluorene-based honokiol photocurable solder resist ink, the preparation method comprising the following steps:

[0055] S1: Mix the fluorenyl honokiol photocurable resin with the solvent and stir at a speed of 1300-1800 r / min for a while;

[0056] S2: Add photoinitiator and nanofiller, and stir at 1300-1800r / min until uniform;

[0057] S3: Grind the mixed material in step S2 to a fineness of less than 8μm, and then add the additives and mix evenly;

[0058] S4: Adjust the viscosity to 500±50 Pa·s with an active diluent, and filter to obtain the finished product.

[0059] In some embodiments, the preparation method of the fluorenyl honokiol photocurable resin includes the following steps:

[0060] (1) Dissolve 9-fluoreneacetic acid in an organic solvent, slowly add thionyl chloride dropwise under stirring, heat the mixture to 60-80℃, and react for 4-8 hours; after the reaction is complete, recrystallize with organic solvent, filter, and wash the filtrate with distilled water several times; then separate and dry the combined organic layers with anhydrous Na2SO4, concentrate the dried organic layers under vacuum, and dry them in a vacuum oven at 60℃ to finally obtain 9-fluoreneacetic anhydride;

[0061] (2) Add 9-fluorene-based acetic anhydride and magnolol to a flask, add sulfuric acid as a catalyst, stir at 70°C for 8 hours to obtain fluorene-based magnolol photocurable resin.

[0062] In some embodiments, in step (1), the organic solvent includes at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate.

[0063] The molar ratio of magnolol, 9-fluoreneacetic acid and thionyl chloride monomer is 1:2-4:2-4.

[0064] In some embodiments, the molar ratio of the 9-fluoreneacetic anhydride to the magnolol monomer is 1:1-1.2.

[0065] In some embodiments, the present invention selects photocurable solder resist ink prepared using 9-fluoreneacetic acid, and the resulting cured film after coating and curing has the properties of low dielectric constant and low dielectric loss.

[0066] 9-Fluorideacetic acid, chemical formula C 15 H 10O2 (CAS: 4425-73-4) is an organic compound with fluorene as its parent structure. Its molecule possesses a unique structure with conjugated double bonds and carboxylic acid groups. This structure combines the rigid planar conjugation properties of fluorene compounds with the reactivity of carboxylic acids, making it suitable as an intermediate in the synthesis of polymers. It can be used to prepare resins and polymers with specific properties, showing potential application value in optoelectronic materials and functional polymers. Its chemical structural formula is as follows:

[0067]

[0068] Fluorene is a rigid planar polycyclic aromatic hydrocarbon formed by two benzene rings bridged by a methylene group. Its conjugated structure endows the molecule with low polarity and high stability, while the high reactivity of the carbon atom at position 9 allows for the introduction of functional groups such as epoxy groups and acrylates. Introducing fluorene structures into resins can significantly reduce the dielectric constant, suppress dielectric loss, and enhance high-temperature stability. These properties make it a key material in fields such as 5G communication and high-frequency substrates.

[0069] The structural formula of the fluorenyl honokiol photocurable resin is shown in formula (I) below:

[0070]

[0071] The reaction route of the 9-fluoreneacetic acid-modified fluorene-mhomonasin photocurable resin is shown below:

[0072]

[0073] Through the above reaction route, it can be clearly seen that each mole of phenolic hydroxyl group can be converted into one mole of 9-fluoreneacetic anhydride through esterification, thereby introducing one mole of fluorene group, thus obtaining fluorene-magnoliol photocurable resin modified with fluorene-magnoliol atomically unsaturated active monomer.

[0074] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments.

[0075] Example 1

[0076] The preparation method of the fluorenyl honokiol photocurable resin includes the following steps:

[0077] (1) Dissolve 9-fluoreneacetic acid in an organic solvent in a three-necked round-bottom flask. Add thionyl chloride dropwise slowly through a dropping funnel while stirring. Heat the mixture to 70°C and react for 6 hours. Connect a gas absorption device (such as NaOH solution) to the upper end of the condenser to absorb the escaping SO2 and HCl, preventing contamination. Then, heat the system to 90°C and distill under reduced pressure to remove unreacted SOCl2 and byproducts (SO2, HCl). After the reaction is complete, recrystallize using an organic solvent (such as petroleum ether), filter, and transfer the filtrate to a separatory funnel. Wash repeatedly with distilled water. Separate the combined organic layers with anhydrous Na2SO4 and dry overnight. Concentrate the dried organic layers under vacuum and dry in a vacuum oven at 60°C for 48 hours to obtain 9-fluoreneacetic anhydride.

[0078] (2) Add 9-fluorene-based acetic anhydride and magnolol to a flask, add sulfuric acid as a catalyst, stir at 70°C for 8 hours to obtain fluorene-based magnolol photocurable resin.

[0079] The molar ratio of magnolol, 9-fluoreneacetic acid and thionyl chloride monomer is 1:3:3.

[0080] In step (1), the organic solvent is propylene glycol methyl ether.

[0081] Weigh out 60 parts of fluorenyl honokiol photocurable resin, 15 parts of reactive diluent, 2 parts of photoinitiator, 10 parts of nanofiller, 1 part of additive, and 12 parts of solvent for later use.

[0082] The reactive diluent is prepared by mixing tripropylene glycol diacrylate and trimethylolpropane triacrylate in a 1:1 ratio.

[0083] The photoinitiator is 2-ethylanthraquinone.

[0084] The nanofiller is silicon dioxide powder.

[0085] The additives include leveling agents and defoamers, wherein the leveling agent is an organosilicon compound and the defoamer is polyoxyethylene-polyoxypropylene block copolymer L62, with a ratio of 7:3, and the leveling agent is the main component.

[0086] The solvent is cyclohexanone.

[0087] In a cleanroom environment, fluorene-based honokiol photocurable resin and solvent were first mixed and stirred at 1500 rpm for 240 min at room temperature. Then, photoinitiator and nanofiller were added sequentially, and the mixture was stirred at 1500 rpm for 20 min. The mixed material was ground to a fineness of less than 8 μm, and then additives were added and mixed evenly. The evenly mixed material was tested, and after testing, the viscosity was adjusted to 500 Pa·s with an active diluent. After filtration, the solder resist ink was obtained.

[0088] When preparing a solder resist coating using the photocurable solder resist ink described in this invention, it is applied to a substrate, dried appropriately (approximately 60–120°C), and then exposed via a patterned film or similar means to obtain a cured coating, thereby developing the unexposed areas. During development, the aforementioned solvent or commonly used halogen-based solvents such as trichloroethylene can be used for solvent development. After development, it is preferable to further heat-cure the photocured coating by performing a heat treatment at approximately 140–200°C for 1 hour.

[0089] Example 2

[0090] Unlike Example 1, in the preparation of the solder resist ink, 50 parts of fluorenyl honokiol photocurable resin, 15 parts of reactive diluent, 2 parts of photoinitiator, 10 parts of nanofiller, 1 part of additive, and 22 parts of solvent were weighed and set aside.

[0091] Example 3

[0092] Unlike Example 1, in the preparation of the solder resist ink, 40 parts of fluorenyl honokiol photocurable resin, 15 parts of reactive diluent, 2 parts of photoinitiator, 10 parts of nanofiller, 1 part of additive, and 32 parts of solvent were weighed and set aside.

[0093] Example 4

[0094] Unlike Example 1, in the preparation of the solder resist ink, 30 parts of fluorenyl honokiol photocurable resin, 15 parts of reactive diluent, 2 parts of photoinitiator, 10 parts of nanofiller, 1 part of additive, and 42 parts of solvent were weighed and set aside.

[0095] Table 1. Raw materials and content of each application example corresponding to the embodiments.

[0096]

[0097] The properties of the inks obtained in each embodiment were tested, and the test results are shown in Table 3. The test methods are as follows:

[0098] ① Pencil hardness was tested according to GB / T6739-2006 "Determination of Hardness of Paints and Varnishes by Pencil Method"; ② The adhesion of the coating was determined using an HGQ type paint film cross-cut tester according to GB / T9268□1998. If the area of ​​coating peeling off is less than 5%, the adhesion performance is judged as √, otherwise it is ×; ③ The temperature resistance test is the temperature data that the sample coated with solder resist ink can withstand after three solder resistance tests for 10 seconds according to GB / T 4677□2002; ④ The application example coating was immersed in 10 vol% H2SO4 and 10 wt% NaOH for 30 min, rinsed with clean water and dried. Tear the material three times with 3M tape. If no oil comes off, the acid and alkali resistance test is √; otherwise, it is ×. ⑤ Flame retardancy is tested according to GB / T 22472□2008: Prepare a 125mm×13mm×3mm sample of the mixed resin and conduct a vertical burning test. Classify the flame retardancy level of the material according to the test results and with reference to Table 2. ⑥ At 10GHz frequency, the dielectric constant and dielectric loss are tested according to ASTM D150 standard.

[0099] Table 2. Flame Retardant Test Material Classification Table

[0100]

[0101] Table 3 Performance Tests of Each Application Example and Comparative Application Examples

[0102]

[0103]

[0104] As shown in Table 3, the resins used in Examples 1-4 were all fluorenyl magnolol photocurable resins prepared in Example 1, with the only difference being the proportion of fluorenyl magnolol photocurable resin. By changing the proportion of the matrix resin, it was found that a higher proportion of fluorenyl magnolol photocurable resin had little impact on the flame retardant properties of the coating, but resulted in higher pencil hardness, better heat resistance, and better dielectric properties. This indicates that under the same formulation conditions, a higher amount of fluorenyl magnolol photocurable resin resulted in better flame retardant properties of the coating. The reason for this is that the biphenyl structure is a planar rigid framework with fixed bond angles and bond lengths, making it difficult to rotate or deform. When it participates in resin crosslinking, the biphenyl unit acts as a "rigid bridging group" embedded in the polymer network, restricting chain segment movement and thus increasing the resin's modulus and hardness. Allyl double bonds (C=C) can undergo free radical polymerization through thermal or photoinitiation, forming a three-dimensional crosslinked structure with the resin matrix. The higher the crosslinking density, the higher the resin hardness. The oxidative decomposition of allyl groups generates carbon-containing free radicals, which can quench hydroxyl radicals (·OH) generated during combustion and inhibit flame spread. Simultaneously, the carbon layer formed by double bond polymerization can isolate oxygen and heat. The rigid planar polycyclic aromatic hydrocarbon formed by the two benzene rings bridged by methylene groups in the fluorene structure possesses a conjugated structure that endows the molecule with low polarity and high stability. Introducing the fluorene structure into resins can significantly reduce the dielectric constant, suppress dielectric loss, enhance high-temperature stability, and increase the glass transition temperature.

[0105] In summary, this invention provides a fluorene-based honokiol resin-based photocurable solder resist ink through a low-cost and simple process. While providing good flame retardant properties to meet the requirements of soldering, it also ensures good processability and heat resistance, and has a low dielectric constant.

[0106] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A fluorene-based honokiol photocurable solder resist ink, characterized in that: The raw material components, by weight, are as follows: 20%-60% fluorenyl honokiol photocurable resin, 10%-25% reactive diluent, 10%-30% nanofiller, 1%-5% photoinitiator, 0.1%-5% additives, and the balance being solvent.

2. The solder resist ink according to claim 1, characterized in that: The fluorenyl honokiol photocurable resin is prepared by reacting 9-fluoreneylic acid with thionyl chloride, and then reacting the intermediate product fluoreneic anhydride with honokiol; wherein the molar ratio of honokiol, thionyl chloride and 9-fluoreneylic acid is 1:2-4:2-4.

3. The solder resist ink according to claim 1, characterized in that: The structural formula of the fluorene-based honokiol photocurable resin is shown in formula (I) below:

4. The solder resist ink according to claim 1, characterized in that: The content of the fluorenyl honokiol photocurable resin is 60%; the content of the reactive diluent is 15%; the content of the nanofiller is 20%; and the content of the photoinitiator is 2%.

5. The solder resist ink according to claim 1, characterized in that: The reactive diluent is one or more of tripropylene glycol diacrylate, trimethylolpropane triacrylate, β-hydroxyethyl methacrylate, and pentaerythritol triacrylate; The nanofiller is one or more of silica powder, talc powder, fumed silica, and barium sulfate; The photoinitiator is one or more of 2-ethylanthraquinone, benzoin diethyl ether 651, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone; The additives include leveling agents and defoamers. The leveling agent is an organosilicon compound with a content of 0.5%-2%, and the defoamer is polyoxyethylene-polyoxypropylene block copolymer L62 with a content of 0.5%-2%. The ratio of leveling agent to defoamer is 7:3, with leveling agent as the main component. The solvent is at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate.

6. The solder resist ink according to claim 5, characterized in that: The leveling agent content is 1.4%, and the defoamer content is 0.6%.

7. A method for preparing fluorenyl honokiol photocurable solder resist ink according to any one of claims 1-6, characterized in that: The preparation method includes the following steps: S1: Mix the fluorenyl honokiol photocurable resin with the solvent and stir at a speed of 1300-1800 r / min for a while; S2: Add photoinitiator and nanofiller, and stir at 1300-1800r / min until uniform; S3: Grind the mixed material in step S2 to a fineness of less than 8μm, and then add the additives and mix evenly; S4: Adjust the viscosity to 500±50 Pa·s with an active diluent, and filter to obtain the finished product.

8. The method for preparing fluorene-based honokiol photocurable solder resist ink according to claim 7, characterized in that: The preparation method of the fluorenyl honokiol photocurable resin includes the following steps: (1) Dissolve 9-fluoreneacetic acid in an organic solvent, slowly add thionyl chloride dropwise under stirring, heat the mixture to 60-80℃, and react for 4-8 hours; after the reaction is complete, recrystallize with organic solvent, filter, and wash the filtrate with distilled water several times; then separate and dry the combined organic layers with anhydrous Na2SO4, concentrate the dried organic layers under vacuum, and dry them in a vacuum oven at 60℃ to finally obtain 9-fluoreneacetic anhydride; (2) Add 9-fluorene-based acetic anhydride and magnolol to a flask, add sulfuric acid as a catalyst, stir at 70°C for 8 hours to obtain fluorene-based magnolol photocurable resin.

9. The method for preparing fluorene-based honokiol photocurable solder resist ink according to claim 8, characterized in that: In step (1), the organic solvent includes at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate. The molar ratio of magnolol, 9-fluoreneacetic acid and thionyl chloride monomer is 1:2-4:2-4.

10. The method for preparing fluorene-based honokiol photocurable solder resist ink according to claim 8, characterized in that: The molar ratio of 9-fluoreneacetic anhydride to magnolol monomer is 1:1-1.2.

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