Application method of a photosensitive solder resist ink with a high glass transition temperature

Abstract

The present invention provides an application method for a photosensitive solder resist ink with a high glass transition temperature. The photosensitive solder resist ink is mainly composed of an alkali-soluble photosensitive epoxy resin modified with an alkynyl active monomer and a photoinitiator. The alkali-soluble photosensitive epoxy resin modified with the alkynyl active monomer is obtained by first carrying out a ring-opening reaction between an epoxy resin and an alkynyl active monomer, and then carrying out an esterification reaction with an unsaturated anhydride. The present invention grafts and modifies the epoxy resin with an alkynyl active monomer to prepare a photosensitive solder resist ink with a high glass transition temperature, which is suitable for the production and manufacturing of PCB substrates in the development and application of high-end fields. In addition, through experiments, it is found that when applying this photosensitive solder resist ink with a high glass transition temperature, it can still have a high glass transition temperature when the conversion rate of its triple bond is relatively low under specific curing conditions, breaking the traditional understanding of curing conditions and the conversion rate of unsaturated bonds in the past.

Description

[0001] This application is a divisional application. The original application number is: 202210645518.5, the application date is: June 8, 2022, and the invention title is: A novel photo-curable solder resist ink with a high glass transition temperature. Technical Field

[0002] The present invention belongs to the technical field of photo-curable solder resist inks, and particularly relates to a novel photo-curable solder resist ink with a high glass transition temperature. Background Art

[0003] A printed circuit board (PCB) is a substrate for modern electrical component installation and connection, and is an important basic assembly in the electronics industry.

[0004] Among them, photo-curable solder resist ink is one of the key materials for printed circuit boards (PCBs). It refers to a protective coating covering the copper wires of printed circuits, which is used to prevent circuit corrosion and breakage, prevent short circuits caused by excessive solder joints, adjust the solder adhesion amount, reduce the dissolution pollution of copper in the weld seam, save solder, reduce the weight of the instrument, increase the high density of wiring, avoid false soldering, and improve the inspection speed.

[0005] With the advent of high-frequency communication, PCB substrates are also developing towards high density and refinement, and the performance requirements for solder resist coatings are also getting higher and higher. Usually, in the PCB processing process, a lead-tin soldering process above 260 °C is required, that is, it needs to be resistant to solder heat treatment. Among them, the glass transition temperature of the solder resist ink is the most critical.

[0006] Traditional photo-curable solder resist inks usually consist of components such as polymerizable monomers, photoinitiators, and inhibitors. At present, the photo-curable solder resist inks commonly used in solder resist films generally include a photo-polymerization initiator and a combination of a photo-curable and thermo-curable resin containing carboxyl groups. Among them, the photo-curable and thermo-curable resin is generally epoxy acrylate resin. Although it has advantages such as good photo-curability, developability, and mechanical properties, the crosslinking density of the cured film is not large after curing, resulting in poor heat resistance. It is easy to foam or lose oil during soldering and cannot meet the requirements on high-demand electrical circuit boards. In addition, its resolution is low and it is not suitable for making high-precision circuit boards, which is not conducive to the development and application of solder resist inks in high-end fields.

[0007] Through the long-term research experience summary of the inventor and referring to the existing technical literature, it is found that in order to increase the glass transition temperature of photo-curable solder resist inks, those skilled in the art often use modified photo-curable epoxy resins to increase the content of unsaturated double bonds in the ink system, and then increase the crosslinking density to obtain a solder resist ink with a high glass transition temperature.

[0008] For example, the inventors of the present invention's previously authorized invention patent "A High-Heat-Resistant and High-Crosslinking-Density Photo-Curable Solder Mask Ink and Its Preparation Method" (CN110527350B) increased the density of unsaturated double bonds in the system by increasing the hydroxyl density of the system, and increased the crosslinking density after curing, so that the cured product has good heat resistance. However, in the above technical solution, it is obvious that in order to increase the density of unsaturated double bonds in the system, on the one hand, it is necessary to replace acrylic acid with a dihydroxy group carboxylic acid with a longer carbon chain and more branched chains on the photo-curable epoxy resin, and on the other hand, more hydroxyl groups are required, so an unsaturated anhydride with double the molar amount is added to achieve a higher double bond density, and then the product has a higher crosslinking density.

[0009] In the specific production practice process of the above previously authorized invention patent, it was found that when the content of the added unsaturated anhydride is greater than a certain value (the threshold values of different systems may vary), due to the excessive double bond content and the enhanced steric hindrance effect in the system during the resin synthesis process, gelation is likely to occur during the preparation process, resulting in reaction failure and difficulty in preparation; and when the amount of anhydride added is too large, the acid value of the prepared solder mask ink will be too high, and overdevelopment is likely to occur during use. At the same time, when the chain length of the grafted compound in the system is relatively large, that is, the density of flexible chains in the system increases, the glass transition temperature of the cured material will decrease, and the heat resistance of the material will be damaged.

[0010] Therefore, it is necessary to provide a photo-curable solder mask ink with a high glass transition temperature from a new perspective, which can not only have very excellent heat resistance but also keep the product quality excellent. Summary of the Invention

[0011] In order to solve the above problems in the prior art, the present invention provides a new type of photo-curable solder mask ink with a high glass transition temperature, and a photo-curable solder mask ink with a high glass transition temperature is prepared by grafting and modifying epoxy resin with an alkynyl active monomer.

[0012] To achieve the above object, the present invention is realized by a technical solution composed of the following technical measures.

[0013] A new type of photo-curable solder mask ink with a high glass transition temperature, the raw materials of which mainly include, by weight:

[0014] 100 parts of an alkali-soluble photo-curable epoxy resin modified with an alkynyl active monomer,

[0015] 1 - 10 parts of a photoinitiator;

[0016] Among them, the alkali-soluble photo-curable epoxy resin modified with an alkynyl active monomer is obtained by first carrying out a ring-opening reaction between an epoxy resin and an alkynyl active monomer, and then carrying out an esterification reaction with an unsaturated anhydride;

[0017] The alkyne-containing active monomer is a monomer having an active group capable of reacting with an epoxy group and at least one alkyne group in its molecular structure, and the number of carbon atoms is not higher than 5;

[0018] The unsaturated acid anhydride is any one of tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride;

[0019] The alkyne-containing active monomer is added in a molar ratio of (1 to 1.2):1 to the epoxy groups of the epoxy resin, and the unsaturated acid anhydride is added in a molar ratio of (1 to 1.2):1 to the epoxy groups of the epoxy resin.

[0020] Among them, the epoxy resin selected has a viscosity of 700 to 20,000 mPa·s at 25°C and an epoxy equivalent of 180 to 280 g / eq.

[0021] Preferably, the epoxy resin selected includes any one of bisphenol A epoxy resin, phenol novolac epoxy resin, o-cresol novolac epoxy resin, p-tert-butylphenol novolac epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, diglycidyl phthalate, diglycidyl tetrahydrophthalate, triglycidyl isocyanurate, and dicyclopentadiene diepoxide.

[0022] Generally, the photoinitiator is a commonly used photoinitiator in the photo-curable solder resist ink in the art, and those skilled in the art can select a suitable photoinitiator according to the existing technical literature or actual process conditions.

[0023] Generally, the alkyne-containing active monomer is a monomer having an active group capable of reacting with an epoxy group and at least one alkyne group in its molecular structure, and the active group capable of reacting with an epoxy group includes any one of a carboxyl group, an amino group, and an acid anhydride.

[0024] To further reduce the influence of steric hindrance, preferably, the number of active groups capable of reacting with an epoxy group in the alkyne-containing active monomer is 1, and the number of alkyne groups in the alkyne-containing active monomer is 1.

[0025] To better illustrate the present invention and provide a reference for the selection of alkyne-containing active monomers, the alkyne-containing active monomer is preferably any one of propiolic acid, 2-butynoic acid, 1-butynoic acid, 1-pentynoic acid, 2-pentynoic acid, and propynamine.

[0026] The inventive point of the present invention lies in that the alkyne group provides unsaturated bonds. One mole of alkyne group has two moles of unsaturation, which is greater than the one mole of saturation of one mole of alkene group. Theoretically, a network space structure with a higher crosslinking density can be formed during the crosslinking and curing process. Therefore, one mole of alkyne group can replace two moles of alkene group, which can weaken the steric hindrance effect in the system and at the same time has a higher crosslinking reaction efficiency.

[0027] To better illustrate the principle of the present invention, one of the technical solutions is taken as an example for illustration:

[0028] When the unsaturated anhydride is selected as tetrahydrophthalic anhydride and the alkyne-containing active monomer is selected as propiolic acid or 2-butynoic acid, the reaction routes of the alkali-soluble photocurable epoxy resins modified by the alkyne-containing active monomer (named (a) EPAT and (b) EBAT respectively) are as follows:

[0029]

[0030] Through the above reaction routes, it can be clearly seen that each mole of epoxy group can correspond to one mole of propiolic acid or 2-butynoic acid through ring-opening reaction, thereby introducing one mole of unsaturated triple bonds. Each branch of the obtained product has 1 hydroxyl group, which can correspond to 1 mole of unsaturated anhydride (especially monobasic anhydride) through esterification reaction. At this time, each branch of the obtained product has 1 carboxyl group, that is, the alkali-soluble photocurable epoxy resin modified by the alkyne-containing active monomer is obtained.

[0031] Furthermore, when selecting the alkyne-containing active monomer, according to the common knowledge in the art, propiolic acid has higher activity due to the terminal alkyne group than 2-butynoic acid. Therefore, in the technical solution using propiolic acid during the photocuring process, the conversion rate of the unsaturated triple bond is higher than that of the technical solution using 2-butynoic acid. For example, the photocurable solder mask ink prepared by propiolic acid has a photocuring conversion rate of 98.5% under the conditions of ultraviolet light irradiation for 40 min and heat curing for 1 h, while the photocurable solder mask ink prepared by 2-butynoic acid has a photocuring conversion rate of only 38.5% under the same conditions. The level of photocuring conversion rate can indirectly illustrate its crosslinking density. That is, only through the above comparative experiment, it can be considered that the crosslinking density of the coating film in the technical solution using propiolic acid is higher than that of the coating film in the technical solution using 2-butynoic acid. Therefore, without considering the influence of steric hindrance, theoretically the glass transition temperature of the former coating film should be significantly higher than that of the latter coating film.

[0032] However, the inventors of the present invention unexpectedly found during the implementation of the experiment that for the photocurable solder resist ink actually prepared using propiolic acid, the glass transition temperature of the film after use was 140.6 °C; while for the photocurable solder resist ink prepared using 2-butynoic acid, the glass transition temperature of the film after use was 143.2 °C. Obviously, the experimental results did not conform to the above theoretical speculation, and the technical effect of the prepared product was clearly beyond the expectation of those skilled in the art. The mechanism for why the technical solution using 2-butynoic acid has a higher glass transition temperature is temporarily unclear.

[0033] It should be emphasized additionally that the inventors also found through comparative experiments that the selection of the unsaturated anhydride is a key factor. When the inventors compared the use of conventional unsaturated anhydrides in the art, it was found that when the unsaturated anhydride was selected as itaconic anhydride, maleic anhydride and other conventional unsaturated anhydrides, very serious gelation occurred after the esterification reaction, and it was impossible to further prepare the photocurable solder resist ink. The same phenomenon also occurred after replacing other types of epoxy resins. Therefore, through actual experimental verification, the unsaturated anhydride in the technical solution of the present invention can only be limited to any one of tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride.

[0034] The occurrence of the above gelation phenomenon may be speculated to be caused by the too high activity of the alkynyl group. This phenomenon is somewhat similar to the gelation phenomenon caused by the relatively complex spatial conformation and the too large addition ratio of the anhydride in the prior authorized invention of the present invention, "A Photocurable Solder Resist Ink Suitable for High-Frequency Communication and Its Preparation Method". However, in the experimental records of the above prior authorized invention, the above gelation phenomenon can also be prevented by adjusting the molar amount of the unsaturated anhydride. The above phenomenon only occurs when the unsaturated anhydride is added in a large amount (the addition of the unsaturated anhydride is carried out in a molar ratio of 4:1 to the epoxy group of the epoxy resin). In the present invention, when the unsaturated anhydride is added in an appropriate amount (the addition of the unsaturated anhydride is carried out in a molar ratio of 1:1 to the epoxy group of the epoxy resin), a very serious gelation phenomenon occurs, and thus it is impossible to prepare the solder resist ink product. It is temporarily impossible to reasonably infer the cause of this technical problem. Therefore, based on the spirit of seeking truth from facts in experimental facts, the technical solution of the present invention only limits the tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride that have been experimentally verified not to show gelation phenomenon as the selection of the unsaturated anhydride.

[0035] Furthermore, in order to better illustrate the present invention, a preparation method of an alkynyl-containing active monomer-modified alkali-soluble photocurable epoxy resin is provided for reference, including the following steps:

[0036] (1) Under a nitrogen atmosphere, preheat the solvent to 70 - 90 °C, add epoxy resin and dissolve it. After cooling to 50 - 60 °C, add the alkyne-containing active monomer and inhibitor, then heat up to 70 - 80 °C, add the cyclic ester ring-opening polymerization catalyst, and then adjust the temperature to 80 - 120 °C. Stir and react for 3 - 6 hours until the acid value of the reaction solution is less than 3 mgKOH / g, then an epoxy resin solution containing the alkyne-containing active monomer is obtained;

[0037] (2) Cool the epoxy resin solution containing the alkyne-containing active monomer obtained in step (1) to 70 - 80 °C, then add and mix the unsaturated anhydride and inhibitor, and continue to stir and react at 90 - 100 °C for 3 - 7 hours to obtain an alkali-soluble photocurable epoxy resin modified with the alkyne-containing active monomer.

[0038] Generally, the cyclic ester ring-opening polymerization catalyst described in step (1) is a cyclic ester ring-opening polymerization catalyst commonly used in the epoxy resin ring-opening polymerization reaction in the technical field of the present invention. Those skilled in the technical field of the present invention can select a suitable cyclic ester ring-opening polymerization catalyst according to actual needs. For the convenience of further illustrating the present invention, preferably, the cyclic ester ring-opening polymerization catalyst described in step (1) is one of triethylamine, triethanolamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, tetramethylammonium chloride, N,N-dimethylbenzylamine, and triphenylphosphine; the addition amount of the cyclic ester ring-opening polymerization catalyst is 0.2 - 1 wt% of the epoxy resin.

[0039] Generally, the solvent described in step (1) is selected from solvents commonly used in the technical field of the present invention for preparing epoxy resin solutions from epoxy resins. Those skilled in the technical field of the present invention can select a suitable solvent according to the selection of epoxy resin and actual needs. For the convenience of further illustrating the present invention, the solvent described in step (1) is at least one of high-boiling-point environmentally friendly solvents of dibasic acid esters, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, mesitylene, and pseudocumene; in step (1), the mass ratio of the solvent to the epoxy resin = (0.5 - 1.5):1.

[0040] Among them, for the addition of the alkyne-containing active monomer in step (1), in order to improve the reaction efficiency and reduce the loss caused by the adhesion of solid reactants to the reaction vessel wall, it is usually selected to first dissolve the alkyne-containing active monomer in an appropriate amount of solvent and then add it; the solvent can be the same solvent as that used to dissolve the epoxy resin above.

[0041] Among them, for the addition of the cyclic ester ring-opening polymerization catalyst in step (1), in order to improve the reaction efficiency and reduce the loss caused by the adhesion of solid reactants to the reaction vessel wall, it is usually selected to first dissolve the cyclic ester ring-opening polymerization catalyst in an appropriate amount of solvent and then add it; the solvent can be the same solvent as that used to dissolve the epoxy resin above.

[0042] Among them, for the addition of unsaturated anhydride in step (2), in order to improve the reaction efficiency and reduce the loss caused by the adhesion of solid reactants to the reaction vessel wall, it is usually preferred to first dissolve the unsaturated anhydride in an appropriate amount of solvent and then add it; the solvent can be the same solvent as that for dissolving epoxy resin above.

[0043] Among them, the polymerization inhibitors used in steps (1) and (2) are the polymerization inhibitors commonly used in the art for photo-curable solder resist inks. Those skilled in the art can select appropriate polymerization inhibitors according to the selection of epoxy resin and actual requirements. For the convenience of explaining the present invention, the polymerization inhibitors described in steps (1) and (2) are selected from at least one of hydroquinone, o-methylhydroquinone, p-methoxyphenol, p-benzoquinone, and 2,6-di-tert-butyl-4-methylphenol. Preferably, the polymerization inhibitors added twice are the same polymerization inhibitor, and the addition amount of the polymerization inhibitor is 0.4-2.5 wt% of the epoxy resin described in step (1).

[0044] Generally, the stirring reactions described in steps (1) and (2) are the stirring reactions conventionally used in the art, including magnetic stirring or mechanical stirring. Those skilled in the art can select a suitable stirring reaction method according to the production scale or the current process conditions. For better explaining the present invention and providing a process scheme suitable for the laboratory operation environment, the stirring reaction can be carried out under the condition that the stirring rate is 100-300 rpm.

[0045] Furthermore, the novel photo-curable solder resist ink with a high glass transition temperature mainly includes the following raw materials by weight:

[0046]

[0047] Among them, in order to improve the physical strength of the coating film after the solder resist ink is used, the solder resist ink composition includes fillers, and the fillers are well-known inorganic or organic fillers, preferably one or more of titanium dioxide, bentonite, barium sulfate, spherical silica, nano calcium carbonate, and talc. Further, it is preferred to use well-known metal oxides as both fillers and pigments.

[0048] Among them, the additives are one or more combinations of pigments, thermal polymerization inhibitors, tackifiers, defoamers, leveling agents, coupling agents, antioxidants, and rust inhibitors. Generally, the above pigments, thermal polymerization inhibitors, tackifiers, defoamers, leveling agents, coupling agents, antioxidants, and rust inhibitors are well-known and commonly used.

[0049] For the preparation method of the above novel photo-curable solder resist ink with a high glass transition temperature, the preparation method can refer to the prior art to mix all components for preparation. For example, after pre-mixing each component in a blender, it is kneaded with a three-roll mill to obtain the novel photo-curable solder resist ink.

[0050] When using the above solder resist ink, coat it on a substrate, dry it appropriately (about 60 - 120 °C), then expose it through a pattern film, etc., to obtain a cured coating film, and develop the unexposed part. During development, solvent development can be carried out using the above solvents or well-known and commonly used halogen-based solvents such as trichloroethylene. However, since carboxyl groups are introduced into the alkali-soluble photocurable epoxy resin modified with alkynyl active monomers, the unexposed part will dissolve in the alkaline aqueous solution, so alkaline development is preferably carried out. For alkaline solvent development, alkali metal compounds such as sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc. can be selected; alkaline earth metal compounds such as calcium hydroxide can also be selected; alkaline solution ammonia water can also be selected; water-soluble organic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, dimethylpropylamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, dimethylaminoethyl methacrylate, polyethyleneimine, etc. can also be selected.

[0051] After development, it is preferably heat-treated at about 140 - 200 °C for 1 h to further thermally cure the photocured coating film.

[0052] Generally, for the above-mentioned novel photocurable solder resist ink with a high glass transition temperature, in addition to the method of directly coating it in a liquid state onto a substrate, it can also be used in the state of a dry film of a solder resist layer formed by previously coating and drying on a film such as PET.

[0053] Furthermore, although by adopting the above technical solution, the glass transition temperature of the coating film of the photocurable solder resist ink can be significantly increased, the inventors of the present invention noticed that for the novel photocurable solder resist ink prepared by the above technical solution, the coating film requires a long time for ultraviolet curing or a thermosetting-assisted method to have better coating film quality.

[0054] Therefore, to improve the above photocuring reaction rate, the present invention also provides an improved solution:

[0055] A novel photocurable solder resist ink prepared by click chemistry, and its raw materials mainly include, by weight:

[0056] 100 parts of an alkali-soluble photocurable epoxy resin modified with an alkynyl active monomer,

[0057] 10 - 20 parts of a thiol compound,

[0058] 3 - 5 parts of a photoinitiator;

[0059] Among them, the alkali-soluble photocurable epoxy resin modified with an alkynyl active monomer is obtained by first carrying out a ring-opening reaction between an epoxy resin and an alkynyl active monomer, and then carrying out an esterification reaction with an unsaturated acid anhydride.

[0060] The alkynyl-containing active monomer is a monomer having an active group capable of reacting with an epoxy group and at least one alkynyl group in its molecular structure, and the number of carbon atoms is not higher than 5;

[0061] The unsaturated acid anhydride is any one of tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride;

[0062] The addition of the alkynyl-containing active monomer is carried out in a molar ratio of (1 to 1.2):1 to the epoxy groups of the epoxy resin, and the addition of the unsaturated acid anhydride is carried out in a molar ratio of (1 to 1.2):1 to the epoxy groups of the epoxy resin.

[0063] In the above improvement scheme, the thiol-alkyne reaction is generated by adding a thiol compound. The thiol-alkyne reaction is a free-radical-mediated click reaction, which is carried out in two steps: the thiol adds to the carbon-carbon triple bond to form an intermediate vinyl sulfide, and then a thiol-ene reaction occurs with the remaining thiol to form a 1,2-bisadduct. By the addition of the above click reaction, the photocuring reaction rate of the novel photocurable solder resist ink prepared is greatly improved.

[0064] Among them, the thiol compound includes but is not limited to any one of dipentaerythritol hexa(3-mercaptopropionate), tetra(3-mercaptopropyl)trimethoxysilane, and pentaerythritol tetra(3-mercaptopropionate). Those skilled in the art can select a suitable thiol compound according to the above thiol-alkyne reaction.

[0065] Through a control experiment, under the condition of ultraviolet photocuring for 20 min, for the photocurable solder resist ink prepared without adding a thiol compound, the photocuring conversion rates are 16.79% (propiolic acid) and 3.61% (2-butynoic acid) respectively; for the novel photocurable solder resist ink prepared by adding a thiol compound and using click chemical reaction, the photocuring conversion rates are 82.13% (propiolic acid) and 52.59% (2-butynoic acid) respectively.

[0066] Furthermore, for the novel photocurable solder resist ink prepared by using click chemical reaction, its raw materials mainly include, by weight:

[0067]

[0068]

[0069] For the specific selection, precautions, usage methods, and application methods of the above raw materials, reference can be made to the above technical solutions, or adjustments can be made according to the actual situation of those skilled in the art.

[0070] The present invention has the following beneficial effects:

[0071] 1. The present invention graft-modifies epoxy resin with an alkynyl active monomer, increasing the crosslinking density after curing and endowing it with a high glass transition temperature, which is suitable for the production and manufacturing of PCB substrates for high-end applications.

[0072] 2. Through actual experiments, it is found that the novel photocurable solder mask ink prepared by using the alkali-soluble photocurable epoxy resin modified with 2-butynoic acid with lower activity has a better glass transition temperature for the applied coating film.

[0073] 3. Through actual experiments, it is found that the selection of unsaturated anhydride is a key factor. In the technical solution of the present invention, the unsaturated anhydride can only be limited to any one of tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride to avoid the phenomenon of gel during the preparation process.

[0074] 4. The preparation method of the present invention is relatively simple, the reaction degree of each step is very high, and the influence of side reactions involved is very small, thereby improving the overall quality of the product. The technical solution of the present invention is suitable for industrial application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 It is a physical photo of the alkynoic acid-modified alkali-soluble photocurable epoxy resin and (EPAT) 2-butynoic acid-modified alkali-soluble photocurable epoxy resin (EBAT) prepared in Synthesis Example 1 and Synthesis Example 2 of the present invention.

[0076] Figure 2 It is an infrared spectrum diagram of the alkynoic acid-modified alkali-soluble photocurable epoxy resin and (EPAT) 2-butynoic acid-modified alkali-soluble photocurable epoxy resin (EBAT) prepared in Synthesis Example 1 and Synthesis Example 2 of the present invention.

[0077] Figure 3 It is a comparative diagram of the thermal weight loss curves of the coating films of the photocurable solder mask ink prepared in Example 3 and the photocurable solder mask ink prepared in Example 4 of the present invention under different curing conditions. In the figure, the subscripts 20, 60, and 20-1 respectively refer to ultraviolet light curing for 20 minutes, ultraviolet light curing for 60 minutes, and heat curing for 1 hour after ultraviolet light curing for 20 minutes.

[0078] Figure 4 It is a comparative diagram of the loss tangent curves of the DMA test of the photocurable solder mask ink prepared in Examples 1 to 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0079] The present invention will be further described below by way of examples in conjunction with the accompanying drawings. It should be noted that the given examples should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention should still fall within the scope of protection of the present invention.

[0080] In the following examples, the reagents and instruments used are as follows:

[0081] Epoxy cresol novolac (EOCN, epoxy equivalent 200 - 230 g / equiv) was provided by Guangdong Yanmo Technology Co., Ltd.

[0082] The catalyst 4-dimethylaminopyridine (DMAP), the polymer inhibitor hydroquinone (HQ), and 1-hydroxycyclohexyl phenyl ketone (photoinitiator 184) for photopolymerization were all purchased from Chengdu Huaxia Chemical Reagent Co., Ltd.

[0083] 1,2,5,6-Tetrahydrophthalic anhydride (THPA), pentaerythritol tetra(3-mercaptopropionate), ethanol, and 2-(2-ethoxyethoxy)ethyl acetate (DCAC) as solvents were provided by Chengdu Kelong Chemical Engineering Reagent Factory.

[0084] Propiolic acid was purchased from Alfa Aesar Chemical Co., Ltd.

[0085] 2-Butynoic acid was purchased from Adamas.

[0086] Fourier transform infrared spectroscopy (FT-IR) was measured using a Nicolet 560 Fourier transform infrared spectrometer; the thermal stability of the samples was determined by a TG 209F1 thermogravimetric analyzer (Netzsch, Germany).

[0087] Infrared test method: The resin was thinly coated on the surface of a potassium bromide flake crystal, and the transmission method was used for testing;

[0088] Thermogravimetric test method: Weigh 3 - 8 mg of the cured film sample, and heat it from 25 °C to 700 °C at a rate of 10 °C per minute under nitrogen protection;

[0089] DMA test method: The cured film was made into a sample strip about 15 - 25 μm thick, 8 mm wide, and 10 - 12 mm long, and tested from 25 °C to 200 °C at a rate of 5 °C per minute at a frequency of 1 Hz.

[0090] Specific parameters for ultraviolet curing: Ultraviolet light wavelength: 395 nm, intensity: 25.0 mW / cm 2 。

[0091] Specific parameters for thermal curing are as follows: Forced air oven at 150 °C, thermal curing for 1 hour.

[0092] Synthesis Example 1

[0093] The preparation method of the alkali-soluble photocurable epoxy resin modified with the alkyne-containing active monomer described in this synthesis example includes the following steps:

[0094] (1) Under a nitrogen atmosphere, add 100 g of diethylene glycol monoethyl ether acetate (DCAC) to a 1 L three-necked flask equipped with a stirrer, heat up to 85 °C, add 100 g of novolac epoxy resin (EOCN), and keep it at a constant temperature for one hour to fully dissolve it. Cool down to 60 °C and add 33 g of propargylic acid and 1 g of inhibitor hydroquinone dissolved in 40 g of diethylene glycol monoethyl ether acetate (DCAC). Heat up to 70 °C and then add 1 g of catalyst 4-dimethylaminopyridine dissolved in 1 g of diethylene glycol monoethyl ether acetate. Carry out a constant-temperature stirring reaction at 90 °C for 1 hour, then heat up to 100 °C and carry out a constant-temperature stirring reaction for 5 hours until the acid value of the reaction solution is less than 3 mg KOH / g, thus obtaining an epoxy resin solution containing propargylic acid groups;

[0095] (2) Cool down the epoxy resin solution containing propargylic acid groups obtained in step (1) to 80 °C, add 71 g of tetrahydrophthalic anhydride (THPA) and 0.5 g of inhibitor hydroquinone dissolved in 70 g of diethylene glycol monoethyl ether acetate, and heat up to 95 °C for a stirring reaction for 3 hours to obtain the alkali-soluble photocurable epoxy resin modified with propargylic acid.

[0096] The alkali-soluble photocurable epoxy resin modified with propargylic acid obtained in this synthesis example is denoted as EPAT.

[0097] Synthesis Example 2

[0098] The preparation method of the alkali-soluble photocurable epoxy resin modified with the alkyne-containing active monomer described in this synthesis example includes the following steps:

[0099] (1) Under a nitrogen atmosphere, add 100 g of diethylene glycol monoethyl ether acetate (DCAC) to a 1 L three-necked flask equipped with a stirrer, heat up to 85 °C, add 100 g of novolac epoxy resin (EOCN), and keep it at a constant temperature for one hour to fully dissolve it. Cool down to 60 °C and add 39 g of butynoic acid and 1 g of inhibitor hydroquinone dissolved in 40 g of diethylene glycol monoethyl ether acetate (DCAC). Heat up to 70 °C and then add 1 g of catalyst 4-dimethylaminopyridine dissolved in 1 g of diethylene glycol monoethyl ether acetate. Carry out a constant-temperature stirring reaction at 90 °C for 1 hour, then heat up to 100 °C and carry out a constant-temperature stirring reaction for 5 hours until the acid value of the reaction solution is less than 3 mg KOH / g, thus obtaining an epoxy resin solution containing 2-butynoic acid groups;

[0100] (2) Cool down the epoxy resin containing 2-butynoic acid groups obtained in step (1) to 80 °C, add 71 g of tetrahydrophthalic anhydride (THPA) dissolved in 70 g of diethylene glycol monoethyl ether acetate and 0.5 g of inhibitor hydroquinone, and then heat up to 95 °C and stir for reaction for 3 hours to obtain the alkali-soluble photocurable epoxy resin modified with 2-butynoic acid.

[0101] Denote the alkali-soluble photocurable epoxy resin modified with 2-butynoic acid obtained in this synthesis example as EBAT.

[0102] Example 1

[0103] The novel photocurable solder mask ink with a high glass transition temperature in this example mainly includes the following raw materials by weight:

[0104] 100 parts of EPAT,

[0105] 3 parts of photoinitiator;

[0106] Mix the above-mentioned components and their proportion (by weight), pre-mix in a stirrer, and then knead with a three-roll mill to prepare an alkali-developable photocurable solder mask ink.

[0107] After testing, when the photocuring conditions are ultraviolet light irradiation for 40 min followed by thermal curing for 1 h, the glass transition temperature of the coating film is 140.6 °C.

[0108] Example 2

[0109] The novel photocurable solder mask ink with a high glass transition temperature in this example mainly includes the following raw materials by weight:

[0110] 100 parts of EBAT,

[0111] 3 parts of photoinitiator;

[0112] Mix the above-mentioned components and their proportion (by weight), pre-mix in a stirrer, and then knead with a three-roll mill to prepare an alkali-developable photocurable solder mask ink.

[0113] After testing, when the photocuring conditions are ultraviolet light irradiation for 40 min followed by thermal curing for 1 h, the glass transition temperature of the coating film is 143.2 °C.

[0114] Example 3

[0115] The novel photocurable solder mask ink is prepared by click chemistry in this example. The raw materials mainly include the following by weight:

[0116] 100 parts of EPAT,

[0117] 15 parts of pentaerythritol tetrakis(3-mercaptopropionate),

[0118] 3 parts of photoinitiator;

[0119] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0120] After testing, when the photocuring conditions are ultraviolet light irradiation for 40 min followed by thermal curing for 1 h, the glass transition temperature of the coating film is 100.4 °C;

[0121] Example 4

[0122] This example uses click chemistry to prepare a novel photocurable solder resist ink. Its raw materials mainly include, by parts by weight:

[0123] 100 parts of EBAT,

[0124] 15 parts of pentaerythritol tetra(3 - mercaptopropionate),

[0125] 3 parts of photoinitiator;

[0126] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0127] After testing, when the photocuring conditions are ultraviolet light irradiation for 40 min followed by thermal curing for 1 h, the glass transition temperature of the coating film is 105.8 °C.

[0128] Then, for the photocurable solder resist inks prepared in Examples 1 - 4 above, test the triple - bond conversion rate under different curing conditions. The results are as follows in the table:

[0129]

[0130] Synthesis Comparative Example 1

[0131] Replace the tetrahydrophthalic anhydride (THPA) in Synthesis Example 1 with itaconic anhydride, and keep the other process conditions the same as those in Synthesis Example 1.

[0132] During the process of heating to 95 °C and stirring for reaction for 3 h in step (2), very serious gelation occurred, resulting in the inability to continue the reaction.

[0133] Synthesis Comparative Example 2

[0134] Replace the tetrahydrophthalic anhydride (THPA) in Synthesis Example 1 with maleic anhydride, and keep the other process conditions the same as those in Synthesis Example 1.

[0135] During the process of heating to 95 °C and stirring for 3 hours in step (2), a very serious gelation phenomenon occurred, resulting in the inability to continue the reaction.

[0136] Synthesis Comparative Example 3

[0137] Replace the tetrahydrophthalic anhydride (THPA) in Synthesis Example 2 with itaconic anhydride, and the remaining process conditions are the same as those in Synthesis Example 2.

[0138] During the process of heating to 95 °C and stirring for 3 hours in step (2), a very serious gelation phenomenon occurred, resulting in the inability to continue the reaction.

[0139] Synthesis Comparative Example 4

[0140] Replace the tetrahydrophthalic anhydride (THPA) in Synthesis Example 2 with maleic anhydride, and the remaining process conditions are the same as those in Synthesis Example 2.

[0141] During the process of heating to 95 °C and stirring for 3 hours in step (2), a very serious gelation phenomenon occurred, resulting in the inability to continue the reaction.

[0142] Synthesis Example 3

[0143] The preparation method of the alkalisoluble photocurable epoxy resin modified with the alkyne-containing active monomer described in this synthesis example includes the following steps:

[0144] (1) Under a nitrogen atmosphere, preheat propylene glycol methyl ether to 70 °C, add bisphenol A epoxy resin and dissolve it. After cooling to 50 °C, add 2-butynoic acid and p-methoxyphenol, then heat to 70 °C, add triethanolamine, and then adjust the temperature to 100 °C and stir for 5 hours until the acid value of the reaction solution is less than 3 mgKOH / g, then an epoxy resin solution containing an alkyne-containing active monomer is obtained;

[0145] Among them, the mass ratio of propylene glycol methyl ether to bisphenol A epoxy resin = 0.8:1;

[0146] The molar ratio of 2-butynoic acid to the epoxy group of bisphenol A epoxy resin is 1.2:1;

[0147] The addition amount of p-methoxyphenol is 0.5 wt% of bisphenol A epoxy resin;

[0148] The addition amount of triethanolamine is 0.5 wt% of bisphenol A epoxy resin;

[0149] (2) Cool the epoxy resin solution containing the alkyne-containing active monomer obtained in step (1) to 70 °C, then add methyltetrahydrophthalic anhydride and p-methoxyphenol and mix, and continue to stir and react at 90 °C for 7 hours to obtain the alkalisoluble photocurable epoxy resin modified with the alkyne-containing active monomer;

[0150] Among them, the molar ratio of methyltetrahydrophthalic anhydride to the epoxy groups of bisphenol A epoxy resin is 1.2:1;

[0151] The addition amount of p-methoxyphenol is 0.5 wt% of bisphenol A epoxy resin.

[0152] Synthesis Example 4

[0153] For the alkali-soluble photocurable epoxy resin modified with an alkynyl active monomer described in this synthesis example, its preparation method includes the following steps:

[0154] (1) Under a nitrogen atmosphere, preheat mesitylene to 90 °C, add diglycidyl phthalate and dissolve it, cool down to 60 °C, then add 2-butynoic acid and 2,6-di-tert-butyl-4-methylphenol, and then heat up to 80 °C, add tetrabutylammonium bromide, and then adjust the temperature to 120 °C, and stir and react for 3 hours until the acid value of the reaction solution is less than 3 mg KOH / g, then an epoxy resin solution containing an alkynyl active monomer is obtained;

[0155] Among them, the mass of mesitylene: the mass of diglycidyl phthalate = 1.5:1;

[0156] The molar ratio of 2-butynoic acid to the epoxy groups of diglycidyl phthalate is 1:1;

[0157] The addition amount of 2,6-di-tert-butyl-4-methylphenol is 2 wt% of diglycidyl phthalate;

[0158] The addition amount of tetrabutylammonium bromide is 1 wt% of diglycidyl phthalate;

[0159] (2) Cool the epoxy resin solution containing an alkynyl active monomer obtained in step (1) to 80 °C, then add hexahydrophthalic anhydride and 2,6-di-tert-butyl-4-methylphenol and mix, and continue to stir and react at 100 °C for 3 hours to obtain an alkali-soluble photocurable epoxy resin modified with an alkynyl active monomer;

[0160] Among them, the molar ratio of methyltetrahydrophthalic anhydride to the epoxy groups of diglycidyl phthalate is 1.2:1;

[0161] The addition amount of 2,6-di-tert-butyl-4-methylphenol is 2 wt% of diglycidyl phthalate.

[0162] Synthesis Example 5

[0163] For the alkali-soluble photocurable epoxy resin modified with an alkynyl active monomer described in this synthesis example, its preparation method includes the following steps:

[0164] (1) Under a nitrogen atmosphere, preheat propylene glycol methyl ether to 80 °C, add p-tert-butylphenol phenolic epoxy resin and dissolve it. After cooling to 55 °C, add propargylamine and p-benzoquinone, then heat up to 75 °C, add triphenylphosphine, and then adjust the temperature to 100 °C. Stir and react for 5 hours until the acid value of the reaction solution is less than 3 mg KOH / g, then an epoxy resin solution containing an alkynyl active monomer is obtained;

[0165] Among them, the mass ratio of propylene glycol methyl ether to p-tert-butylphenol phenolic epoxy resin is 1:1;

[0166] The molar ratio of propargylamine to the epoxy groups of p-tert-butylphenol phenolic epoxy resin is 1:1;

[0167] The addition amount of p-benzoquinone is 1 wt% of p-tert-butylphenol phenolic epoxy resin;

[0168] The addition amount of triphenylphosphine is 0.8 wt% of p-tert-butylphenol phenolic epoxy resin;

[0169] (2) Cool the epoxy resin solution containing an alkynyl active monomer obtained in step (1) to 75 °C, then add methylhexahydrophthalic anhydride and p-benzoquinone and mix. Continue to stir and react at 95 °C for 5 hours to obtain an alkali-soluble photocurable epoxy resin modified with an alkynyl active monomer;

[0170] Among them, the molar ratio of methylhexahydrophthalic anhydride to the epoxy groups of p-tert-butylphenol phenolic epoxy resin is 1:1;

[0171] The addition amount of p-benzoquinone is 1 wt% of p-tert-butylphenol phenolic epoxy resin.

[0172] Example 5

[0173] The novel photocurable solder resist ink of this example with a high glass transition temperature mainly includes the following raw materials by weight:

[0174] 100 parts of EPAT,

[0175] 8 parts of photoinitiator (photoinitiator 907);

[0176] Mix the above-mentioned various components and their component ratios (by weight), preliminarily mix them in a stirrer, and then knead them with a three-roll mill to prepare an alkali-developable photocurable solder resist ink.

[0177] Example 6

[0178] The novel photocurable solder resist ink of this example with a high glass transition temperature mainly includes the following raw materials by weight:

[0179]

[0180] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0181] Example 7

[0182] The novel photocurable solder resist ink of this example has a high glass transition temperature. Its raw materials mainly include, by parts by weight:

[0183]

[0184]

[0185] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0186] Example 8

[0187] The novel photocurable solder resist ink of this example has a high glass transition temperature. Its raw materials mainly include, by parts by weight:

[0188]

[0189] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0190] Example 9

[0191] The novel photocurable solder resist ink of this example is prepared by click chemistry reaction. Its raw materials mainly include, by parts by weight:

[0192] EPAT 100 parts,

[0193] Dipentaerythritol hexa(3 - mercaptopropionate) 10 parts,

[0194] Photoinitiator 5 parts;

[0195] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0196] Example 10

[0197] The novel photocurable solder resist ink of this example is prepared by click chemistry reaction. Its raw materials mainly include, by parts by weight:

[0198] EBAT 100 parts,

[0199] Tetrakis(3 - mercaptopropyl)silane 20 parts,

[0200] 3 parts of photoinitiator;

[0201] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead and mix them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0202] Example 11

[0203] This example uses click chemistry to prepare a new type of photocurable solder resist ink. Its raw materials mainly include, by parts by weight:

[0204]

[0205] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead and mix them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0206] Example 12

[0207] This example uses click chemistry to prepare a new type of photocurable solder resist ink. Its raw materials mainly include, by parts by weight:

[0208]

[0209]

[0210] Mix the above - shown components and their component ratios (parts by weight), preliminarily mix them in a stirrer, and then knead and mix them with a three - roll mill to prepare an alkali - developable photocurable solder resist ink.

[0211] It should be noted that the selection and proportioning of each component in the above examples are only for conveniently illustrating the technical effects of the present invention. Those skilled in the art should understand that on the premise that the alkali - soluble photocurable epoxy resin modified with alkynyl active monomer is determined, according to the relevant prior art of photocurable solder resist ink, any selection and adjustment of other components except the alkali - soluble photocurable epoxy resin modified with alkynyl active monomer will have the technical effects described in the present invention.

Claims

1. A method for applying a photosensitive solder resist ink with a high glass transition temperature, characterized in that When the high glass transition temperature photocurable solder resist ink is in use, its photocuring conditions are ultraviolet light irradiation for 40 minutes followed by thermal curing for 1 hour; The high glass transition temperature photocurable solder resist ink, by weight, comprises the following raw materials: 100 parts of an alkynyl active monomer-modified alkali-soluble photocurable epoxy resin, 3 parts of a photoinitiator; Among them, the preparation method of the alkynyl active monomer-modified alkali-soluble photocurable epoxy resin comprises the following steps: (1) Under a nitrogen atmosphere, preheat the solvent to 70 - 90 °C, add the epoxy resin and dissolve it, cool down to 50 - 60 °C, then add the alkynyl active monomer and the inhibitor, and then heat up to 70 - 80 °C, add the cyclic ester ring-opening polymerization catalyst, and then adjust the temperature to 80 - 120 °C, stir and react for 3 - 6 hours until the acid value of the reaction solution is less than 3 mgKOH / g, thus obtaining an epoxy resin solution containing an alkynyl active monomer; (2) Cool down the epoxy resin solution containing the alkynyl active monomer obtained in step (1) to 70 - 80 °C, then add the unsaturated acid anhydride and the inhibitor and mix them, and continue to stir and react at 90 - 100 °C for 3 - 7 hours to obtain the alkynyl active monomer-modified alkali-soluble photocurable epoxy resin; The epoxy resin is selected from any one of phenol novolac epoxy resin, o-cresol novolac epoxy resin, and p-tert-butylphenol novolac epoxy resin; The alkynyl active monomer is 2-butynoic acid; The unsaturated acid anhydride is any one of tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride; The addition of the alkynyl active monomer is carried out in a molar ratio of (1 - 1.2):1 to the epoxy groups of the epoxy resin, and the addition of the unsaturated acid anhydride is carried out in a molar ratio of (1 - 1.2):1 to the epoxy groups of the epoxy resin.

2. The application method according to claim 1, wherein: The cyclic ester ring-opening polymerization catalyst in step (1) is one of triethylamine, triethanolamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, tetramethylammonium chloride, N,N-dimethylbenzylamine, and triphenylphosphine; the addition amount of the cyclic ester ring-opening polymerization catalyst is 0.2 - 1 wt% of the epoxy resin.

3. The application method according to claim 1, characterized in that: The solvent in step (1) is at least one of ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, mesitylene, and pseudocumene; in step (1), the mass ratio of the solvent to the epoxy resin is (0.5 - 1.5):

1.

4. The application method according to claim 1, wherein: The inhibitors selected in steps (1) and (2) include at least one of hydroquinone, o-methylhydroquinone, p-methoxyphenol, p-benzoquinone, and 2,6-di-tert-butyl-4-methylphenol; the addition amount of the inhibitor is 0.4 - 2.5 wt% of the epoxy resin in step (1).

5. The application method according to claim 1, characterized in that The high glass transition temperature photocurable solder resist ink, by weight, comprises the following raw materials: 100 parts of an alkynyl active monomer-modified alkali-soluble photocurable epoxy resin, 3 parts of a photoinitiator, 20 - 50 parts of a filler, 1 - 25 parts of an additive.

Images