Fluorine-containing epoxy resin-based photocuring solder resist ink and preparation method thereof

Abstract

The invention provides fluorine-containing epoxy resin-based light-cured solder resist ink and a preparation method thereof. The solder resist ink comprises the following raw material components in percentage by mass: 20-60% of fluorine-containing 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, wherein the fluorine-containing light-cured resin is prepared by the following steps: performing epoxidation reaction on magnolol and epoxy chloropropane to generate an intermediate product epoxy magnolol, and performing ring-opening reaction on the intermediate product epoxy magnolol and chlorotrifluorochrysanthemic acid under the catalysis of a tertiary amine compound. 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] The application belongs to the technical field of high-frequency high-speed electronic circuit packaging materials, and particularly relates to a fluorine-containing epoxy resin-based photocuring solder resist ink and a preparation method thereof, which 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

[0002] Printed circuit boards (PCB) as the key carrier of electronic components, the surface of the solder resist ink bears the core functions of insulation protection, anti-welding short circuit and environmental protection. With the rapid development of 5G communication, satellite navigation and high-frequency electronic equipment, PCB evolves towards high frequency, high speed and high density, which puts forward more stringent performance requirements for solder resist ink. The main way to improve the flame retardance of the current traditional solder resist ink is to add flame retardants (such as aluminum hydroxide and bromine-based flame retardants), which has significant defects. The added flame retardants are easy to migrate and volatilize, resulting in attenuation of the flame retardant function, and the addition amount needs to be more than 30% to meet the basic flame retardant requirements, which seriously affects the film-forming property and mechanical property of the ink. The traditional epoxy acrylate solder resist ink has high dielectric constant (Dk≈3.5-4.0) due to the strong polarity of the molecular chain (containing hydroxyl, ether bond and other polar groups), and the dielectric loss (Df>0.005) is significantly high at 10 GHz high frequency, resulting in signal distortion; at the same time, its heat resistance is insufficient (Tg≈150℃), and it cannot withstand the multiple soldering processes in high-density packaging.

[0003] Epoxy resins (EPs) are an important class of thermosetting polymers, which have excellent properties such as strong adhesion, good mechanical properties, high electrical insulation, and good chemical resistance. EPs are widely used as matrix resins in composite materials in fields such as construction, coatings, machinery, and instruments. Unfortunately, almost all commercial epoxy resins are derived from non-renewable petroleum resources, more than 90% of which are bisphenol A epoxy resins, and the two main reaction monomers are bisphenol A (BPA) and epoxy chloropropane. Although epoxy chloropropane can be commercially produced from bio-based glycerol, BPA still depends entirely on petroleum resources, and its molar mass accounts for more than 67% of the total amount of bisphenol A epoxy resins. In addition, BPA, as an endocrine disruptor, has been classified as a reproductive toxicity R2 substance, which poses a significant threat to human health. Based on the above energy and health problems, developing sustainable and non-toxic bio-based epoxy resins to replace BPA has become a research hotspot.

[0004] Magnolol is a bioactive compound extracted from the bark of Magnolia officinalis, commonly used as a herbal medicine and cosmetic ingredient. It has been proven to be a safe substance with very low side effects. Notably, it is also an attractive multifunctional bio-based monomer, naturally containing a symmetrical bisphenol group and a diallyl structure within the molecule, which is very suitable for the synthesis of various bio-based polymers. Allyl groups, as reactive groups, have been widely used to increase the crosslinking density of polymers and improve the processing properties. In addition, the biphenyl structure in magnolol belongs to a highly aromatic group, which, when introduced into a polymer system, not only enhances thermal stability, but also forms a high-temperature-resistant carbon layer during combustion, thereby significantly improving the flame retardance of the material.

[0005] Currently, there are mainly the following ways to prepare solder resist ink:

[0006] Chinese patent CN202010017355.7 discloses a POSS modified photosensitive solder resist ink with low dielectric constant and a preparation method thereof, which comprises the following components by weight fraction: photosensitive resin 25-60 parts; polyimide resin 40-80 parts; modified POSS 10-50 parts; active acrylic monomer diluent 20-40 parts; photoinitiator 2-10 parts; pigment 0-30 parts; auxiliary agent 0-15 parts; the modified POSS is prepared by the following method: mixing POSS and silane coupling agent in a mass ratio of 1:1-5 under ultrasonic to obtain modified POSS. It proposes to use POSS modified resin, but it needs multi-step organic synthesis, which is costly, and the dispersion of nano filler is poor, which easily leads to the increase of dielectric loss.

[0007] Chinese patent CN202510189817.6 discloses a flame-retardant PBT / brominated polycarbonate composition, which comprises the following components by weight fraction: PBT 40-60 parts; brominated polycarbonate 30-50 parts; anti-dripping agent 0.2-0.5 parts; glycidyl methacrylate grafted toughening agent 10-15 parts; the viscosity average molecular weight of the brominated PC is in the range of 13000-30000, and the molar ratio of bisphenol A to tetrabromobisphenol A is 55-40:45-60. It proposes to use an external photocuring halogen-free flame retardant, although this patent solves the problem of flame retardance of solder resist ink to some extent, but does not consider the long-term effectiveness of solder resist ink.

[0008] Therefore, at present, the solder resist ink existing in the market can improve the flame retardance to some extent, but still has problems such as high dielectric constant, complex process, poor flexibility, etc., and there is an urgent need for an improved photocuring solder resist ink with low dielectric constant, high glass transition temperature, simple synthesis and hardness.

SUMMARY

[0009] One of the technical problems to be solved by the present application is to provide a fluorine-containing epoxy resin-based photocuring solder resist ink, which has excellent flame retardant performance, heat resistance, adhesion, low dielectric constant and high hardness, and solves the problems of high dielectric loss, insufficient flame retardancy and BPA toxicity of traditional inks.

[0010] The present application is thus implemented to solve one of the above technical problems:

[0011] A fluorine-containing epoxy resin-based photocuring solder resist ink comprises the following raw material components by mass: 20-60% of a fluorine-containing photocuring resin, 10-25% of an active diluent, 10-30% of a nano filler, 1-5% of a photoinitiator, 0.1-5% of an additive, and the balance of a solvent.

[0012] Further, the fluorine-containing photocuring resin is prepared by ring-opening reaction of an intermediate product, epoxy magnolol, generated after magnolol and epichlorohydrin are subjected to epoxidation reaction, and trifluoro-chlorothymol acid under catalysis of a tertiary amine compound; wherein the molar ratio of magnolol, epichlorohydrin and trifluoro-chlorothymol acid is 1:2-3:2-3.

[0013] Further, the fluorine-containing photocuring resin has the following structural formula (I):

[0014]

[0015] Further, the content of the fluorine-containing photocuring resin is 60%, the content of the active diluent is 15%, the content of the nano filler is 20%, and the content of the photoinitiator is 2%.

[0016] Further, the active diluent is one or more of tripropyleneglycol diacrylate, trimethylolpropane triacrylate, beta-hydroxyethyl methacrylate and pentaerythritol triacrylate;

[0017] The nano filler is one or more of silica powder, talc powder, fumed silica and barium sulfate;

[0018] The photoinitiator is one or more of 2-ethylanthraquinone, benzoin ethyl ether 651, (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide and 2-methyl 1-[4-(methylthio) phenyl]-2-morpholino-1-propanone;

[0019] The additive comprises a leveling agent and a defoaming agent, wherein the leveling agent is an organic silicon compound with a content of 0.5-2%, the defoaming agent is polyoxyethylene-polyoxypropylene block copolymer L62 with a content of 0.5-2%, and the ratio of the leveling agent to the defoaming agent is 6:4, with the leveling agent being dominant.

[0020] The solvent is at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate.

[0021] Furthermore, the leveling agent content is 1.2%, and the defoamer content is 0.8%.

[0022] The second technical problem to be solved by the present invention is to provide a method for preparing a fluorinated epoxy resin-based 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, thus solving the problems of high dielectric loss, insufficient flame retardancy and BPA toxicity of traditional inks.

[0023] The present invention achieves the second technical problem mentioned above in the following way:

[0024] A method for preparing a fluorinated epoxy resin-based photocurable solder resist ink, the method comprising the following steps:

[0025] S1: Mix the fluorine-containing light-curing resin with the solvent and stir at 1300-1800 r / min for a period of time;

[0026] S2: Add photoinitiator and nanofiller, and stir at 1300-1800r / min until uniform;

[0027] S3: Grind the mixed material in step S2 to a fineness of less than 8μm, and then add the additives and mix evenly;

[0028] S4: Adjust the viscosity to 100±20 Pa·s with an active diluent, and filter to obtain the finished product.

[0029] Furthermore, the preparation method of the fluorinated photocurable resin includes the following steps:

[0030] (1) A mixture of magnolol, epichlorohydrin and catalyst benzyltriethylammonium chloride (BTEAC) was stirred for 3 hours under nitrogen protection at 80°C. Then, 40% w / w sodium hydroxide aqueous solution was added dropwise to the reaction system and stirred for 1 hour at 80°C. After the reaction was completed, the inorganic salts generated were removed by filtration and the filtrate was washed with distilled water several times. The combined organic layers were then separated and dried with anhydrous Na2SO4. The dried organic layers were then concentrated under vacuum to remove excess epichlorohydrin and dried in a vacuum oven at 50°C for 24 hours to finally obtain the yellow liquid intermediate product, magnolol.

[0031] (2) Add epoxy magnolol and trifluorochloroquine to the reactor, add tertiary amine monomers, stir at 80°C for 4 hours to obtain fluorine-containing light-curing resin.

[0032] Furthermore, the tertiary amine monomers include at least one of triethylamine, triethanolamine, and 2,4,6-tris(dimethylaminomethyl)phenol;

[0033] The molar ratio of magnolol, epichlorohydrin and tertiary amine monomers is 1:2-3:0.05.

[0034] Furthermore, the molar ratio of the fluorinated epoxy intermediate honokiol to the trifluorochloroquine monomer is 1:2-3.

[0035] The present invention has the following advantages:

[0036] 1. The solder resist ink of this invention contains a fluorinated photocurable resin. This resin is obtained by introducing a fluorinated compound, trifluorochloroquine, into the epoxy product of the reaction of magnolol and epichlorohydrin, followed by a tertiary amine compound catalytic reaction. This fluorinated photocurable resin, as a flame retardant, has a high fluorine content, resulting in a low dielectric constant and flame retardant effect. 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 low experimental conditions, has low viscosity, and exhibits good processability. In summary, this preparation method, by replacing traditional epoxy resin with magnolol, significantly reduces the dielectric constant of the prepared photocurable solder resist ink, and has the significant advantages of outstanding flame retardancy and safe use, making it fully suitable for the production of PCB substrates used in high-frequency communication.

[0037] 2. 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, and post-processing is convenient or unnecessary, making the production process simple and efficient.

[0038] 3. The solder resist ink prepared by this invention has excellent flame retardant properties, heat resistance, adhesion, low dielectric constant and high hardness.

Detailed Implementation Methods

[0039] 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.

[0040] 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.

[0041] This invention relates to a fluorinated epoxy resin-based photocurable solder resist ink, comprising the following raw material components by weight: 20%-60% fluorinated photocurable resin, 10%-25% reactive diluent, 10%-30% nanofiller, 1%-5% photoinitiator, 0.1%-5% additives, and the balance being solvent.

[0042] In some embodiments, the fluorinated photocurable resin is prepared by reacting magnolol with epichlorohydrin via an epoxidation reaction, and then reacting the intermediate product, epichlorohydrin, with trifluorochloroquine acid under the catalysis of a tertiary amine compound to undergo a ring-opening reaction; wherein the molar ratio of magnolol, epichlorohydrin, and trifluorochloroquine acid is 1:2-3:2-3.

[0043] In some embodiments, the fluorinated photocurable resin has the following structural formula (I):

[0044]

[0045] In some embodiments, the content of the fluorinated 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%.

[0046] In some embodiments, the reactive diluent is one or more of tripropylene glycol diacrylate, trimethylolpropane triacrylate, β-hydroxyethyl methacrylate, and pentaerythritol triacrylate;

[0047] The nanofiller is one or more of silica powder, talc powder, fumed silica, and barium sulfate;

[0048] 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;

[0049] 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 6:4, with leveling agent as the main component.

[0050] The solvent is at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, cyclohexanone, and ethyl lactate.

[0051] In some embodiments, the leveling agent content is 1.2%, and the defoamer content is 0.8%.

[0052] The preparation method of the fluorinated epoxy resin-based photocurable solder resist ink includes the following steps:

[0053] S1: Mix the fluorine-containing light-curing resin with the solvent and stir at 1300-1800 r / min for a period of time;

[0054] S2: Add photoinitiator and nanofiller, and stir at 1300-1800r / min until uniform;

[0055] S3: Grind the mixed material in step S2 to a fineness of less than 8μm, and then add the additives and mix evenly;

[0056] S4: Adjust the viscosity to 100±20 Pa·s with an active diluent, and filter to obtain the finished product.

[0057] In some embodiments, the preparation method of the fluorinated photocurable resin includes the following steps:

[0058] (1) A mixture of magnolol, epichlorohydrin and the catalyst benzyltriethylammonium chloride (BTEAC) was stirred for 3 hours under nitrogen protection at 80°C. Then, 40% w / w sodium hydroxide aqueous solution was added dropwise to the reaction system and stirred for 1 hour at 80°C. After the reaction was completed, the inorganic salts generated were removed by filtration and the filtrate was washed with distilled water several times. The combined organic layers were then separated and dried with anhydrous Na2SO4. The dried organic layers were then concentrated under vacuum to remove excess epichlorohydrin and dried in a vacuum oven at 50°C for 24 hours to finally obtain the yellow liquid intermediate product, magnolol.

[0059] (2) Add epoxy magnolol and trifluorochloroquine to the reactor, add tertiary amine monomers, stir at 80°C for 4 hours to obtain fluorine-containing light-curing resin.

[0060] In some embodiments, the tertiary amine monomer includes at least one of triethylamine, triethanolamine, and 2,4,6-tris(dimethylaminomethyl)phenol;

[0061] The molar ratio of magnolol, epichlorohydrin and tertiary amine monomers is 1:2-3:0.05.

[0062] In some embodiments, the molar ratio of the fluorinated epoxy intermediate honokiol to the trifluorochloroquine monomer is 1:2-3.

[0063] In some embodiments, the present invention selects photocurable solder resist ink prepared using trifluorochloroquine (2,2-dimethyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)cyclopropanecarboxylic acid) to obtain a cured film with low dielectric constant and low dielectric loss after coating and curing.

[0064] Trifluorochloroquine, chemical formula C9H 10 ClF3O2 (2,2-dimethyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-cyclopropane hydroxy acid, CAS: 72748-35-7), its chemical structural formula is as follows:

[0065]

[0066] The structural formula of the fluorine-containing photocurable resin is shown in formula (I) below:

[0067]

[0068] The reaction route of the trifluorochlorophenate-modified fluorinated photocurable resin is shown below:

[0069]

[0070]

[0071] Through the above reaction route, it is clear that each mole of epoxy group can correspond to one mole of trifluorochloroquine through a ring-opening reaction, thereby introducing one mole of unsaturated double bond and three moles of fluorine atoms, thus obtaining a fluorine-containing photocurable resin modified with an unsaturated reactive monomer containing fluorine atoms. This invention utilizes the fluorine-containing property of trifluorochloroquine to significantly reduce the dielectric constant and dielectric loss of the prepared photocurable solder resist ink.

[0072] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments.

[0073] Example 1

[0074] The preparation method of the fluorine-containing photocurable resin includes the following steps:

[0075] (1) Magnolol, epichlorohydrin, and the catalyst benzyltriethylammonium chloride (BTEAC) were sequentially added to a three-necked round-bottom flask. The mixture was stirred vigorously for 3 hours under nitrogen protection at 80°C. Subsequently, a 40% w / w sodium hydroxide aqueous solution was added dropwise to the reaction system, and stirring was continued for 1 hour at 80°C. After the reaction was completed, the generated inorganic salts were removed by filtration, and the filtrate was transferred to a separatory funnel and washed repeatedly with distilled water. The combined organic layers were then separated with anhydrous Na2SO4 and dried overnight. The dried organic layers were then concentrated under vacuum to remove excess epichlorohydrin, and then dried in a vacuum oven at 50°C for 24 hours to finally obtain the yellow liquid intermediate product, epichlorohydrin.

[0076] (2) Add epoxy magnolol and trifluorochloroquine to the reactor, add tertiary amine monomers, stir at 80°C for 4 hours to obtain fluorine-containing light-curing resin.

[0077] The tertiary amine monomer is triethylamine; the molar ratio of magnolol, epichlorohydrin, and the tertiary amine monomer is 1:2:0.05. The molar ratio of the fluorinated epoxy intermediate, epichlorohydrin, to the trifluorochloropyric acid monomer is 1:2.

[0078] The method for preparing solder resist ink according to the embodiments of this application is as follows: Weigh 60 parts of fluorine-containing 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.

[0079] The reactive diluent is prepared by mixing tripropylene glycol diacrylate and trimethylolpropane triacrylate in a 1:1 ratio.

[0080] The photoinitiator is 2-ethylanthraquinone.

[0081] The nanofiller is silicon dioxide powder.

[0082] 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 6:4, and the leveling agent is the main component.

[0083] The solvent is cyclohexanone.

[0084] In a cleanroom environment, the fluorinated photocurable resin and solvent were first mixed and stirred at 1500 rpm for 240 min at room temperature. Then, the 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 the additives were added and mixed evenly. The evenly mixed material was tested, and after testing, the viscosity was adjusted to 100 Pa·s with an active diluent. After filtration, the solder resist ink was obtained.

[0085] 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.

[0086] Example 2

[0087] Unlike Example 1, in the preparation of the solder resist ink, 50 parts of fluorine-containing 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.

[0088] Example 3

[0089] Unlike Example 1, in the preparation of the solder resist ink, 40 parts of fluorine-containing 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.

[0090] Example 4

[0091] Unlike Example 1, in the preparation of the solder resist ink, 30 parts of fluorine-containing 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.

[0092] spare.

[0093] Table 1. Raw materials and content of each application example corresponding to the embodiments.

[0094] Example 1 Example 2 Example 3 Example 4 Fluorine-containing photocurable resin 60 50 40 30 Active diluent 15 15 15 15 Photoinitiator 2 2 2 2 Nanofiller 10 10 10 10 Auxiliary agent 1 1 1 1 Solvent 12 22 32 42

[0095] 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:

[0096] 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 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 minutes, 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.

[0097] Table 2. Flame Retardant Test Material Classification Table

[0098]

[0099]

[0100] Table 3 Performance Tests of Each Application Example and Comparative Application Examples

[0101] Test item Example 1 Example 2 Example 3 Example 4 Pencil hardness (H) 7 6 6 5 Adhesion test √ √ √ √ Heat resistance test (°C) 280 265 260 245 Acid and alkali resistance test √ √ √ √ UL-94 test V-0 V-0 V-0 V-0 Dielectric constant ε 2.8 3.1 3.2 3.8 Dielectric loss tan δ 0.013 0.015 0.02 0.023

[0102] As shown in Table 3, the resins used in Examples 1-4 were all the fluorinated photocurable resins prepared in Example 1, with the only difference being the proportion of fluorinated photocurable resin in the solder resist ink. By changing the proportion of the matrix resin, it was found that a higher proportion of fluorinated photocurable resin had little impact on the flame retardant properties of the coating, but resulted in higher pencil hardness, better heat resistance, a lower dielectric constant, and lower dielectric loss, making it suitable for high-frequency, high-speed solder resist inks. This indicates that under the same formulation conditions, a higher amount of fluorinated photocurable resin results 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. When allyl groups are oxidized and decomposed, they produce carbon-containing free radicals, which can quench hydroxyl radicals (·OH) during combustion and inhibit the spread of flames; at the same time, the carbon layer formed by the polymerization of double bonds can isolate oxygen and heat.

[0103] In summary, this invention provides a fluorinated epoxy resin-based photocurable solder resist ink through a low-cost and simple process. While providing good flame retardant properties to meet the requirements of welding, it also ensures good processability and heat resistance, and has a low dielectric constant.

[0104] 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 fluorinated epoxy resin-based photocurable solder resist ink, characterized in that: The raw material components, by weight, are as follows: 20%-60% fluorinated 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 fluorinated photocurable resin is prepared by epoxidation of magnolol and epichlorohydrin, followed by ring-opening reaction of the intermediate product epichlorohydrin with trifluorochloroquine acid under the catalysis of a tertiary amine compound; wherein the molar ratio of magnolol, epichlorohydrin and trifluorochloroquine acid is 1:2-3:2-3.

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

4. The solder resist ink according to claim 1, characterized in that: The content of the fluorinated 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, 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 6:4, 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 1.2%, and the defoamer content is 0.8%.

7. A method for preparing a fluorinated epoxy resin-based 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 fluorine-containing light-curing resin with the solvent and stir at 1300-1800 r / min for a period of time; 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 100±20 Pa·s with an active diluent, and filter to obtain the finished product.

8. The method for preparing solder resist ink according to claim 7, characterized in that: The preparation method of the fluorine-containing photocurable resin includes the following steps: (1) A mixture of magnolol, epichlorohydrin and catalyst benzyltriethylammonium chloride (BTEAC) was stirred for 3 hours under nitrogen protection at 80°C. Then, 40% w / w sodium hydroxide aqueous solution was added dropwise to the reaction system and stirred for 1 hour at 80°C. After the reaction was completed, the inorganic salts generated were removed by filtration and the filtrate was washed with distilled water several times. The combined organic layers were then separated and dried with anhydrous Na2SO4. The dried organic layers were then concentrated under vacuum to remove excess epichlorohydrin and dried in a vacuum oven at 50°C for 24 hours to finally obtain the yellow liquid intermediate product, magnolol. (2) Add epoxy magnolol and trifluorochloroquine to the reactor, add tertiary amine monomers, stir at 80°C for 4 hours to obtain fluorine-containing light-curing resin.

9. The method for preparing solder resist ink according to claim 8, characterized in that: The tertiary amine monomers include at least one of triethylamine, triethanolamine, and 2,4,6-tris(dimethylaminomethyl)phenol; The molar ratio of magnolol, epichlorohydrin and tertiary amine monomers is 1:2-3:0.

05.

10. The method for preparing solder resist ink according to claim 8, characterized in that: The molar ratio of the fluorinated epoxy intermediate magnolol to the trifluorochloroquine monomer is 1:2-3.

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