Preparation method of low-halogen alkali-soluble photosensitive resin and solder resist ink

Abstract

The invention relates to the technical field of electronic materials, in particular to a preparation method of low-halogen alkali-soluble photosensitive resin and solder resist ink. Comprising the following steps: adding amino resin, alcohol olefin and a catalyst A into a solvent, mixing, and carrying out an ether exchange reaction to obtain an initial etherified product; adding peroxide into the initial etherification product, and carrying out epoxidation reaction to obtain an epoxy resin intermediate; adding an olefine acid compound, a catalyst B and a polymerization inhibitor into the epoxy resin intermediate, and carrying out ring-opening esterification reaction to obtain an epoxy acrylate intermediate; and adding acid anhydride into the epoxy acrylate intermediate, and carrying out carboxylation reaction to obtain the low-halogen alkali-soluble photosensitive resin. The problem of high halogen content of the existing alkali-soluble photosensitive resin is solved, and the solder resist ink prepared from the alkali-soluble photosensitive resin has high sensitivity, high resolution, high heat resistance, high acid and alkali resistance and high electrical insulation property.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic materials, and in particular to a preparation method of a low-halogen alkali-soluble photosensitive resin and a solder resist ink. Background Art

[0002] In the chemical production of traditional epoxy resins, excessive use of epichlorohydrin leads to residual chlorine. PCB manufacturing has long relied on halogens as flame retardants. However, these elements release toxic gases such as dioxins upon combustion, polluting the environment and endangering human health through the food chain. With the strengthening of global environmental regulations, the electronics manufacturing industry is transitioning to halogen-free materials. Halogen-free materials replace halogens with phosphorus and nitrogen atoms, reducing the polarity of the epoxy resin molecular chain, significantly improving insulation resistance and breakdown resistance, and enhancing the stability of PCBs in high-frequency and high-temperature environments. The current halogen-free process demonstrates the following trends: first, the continuous optimization of new flame retardant materials (such as organophosphorus-based materials) and production processes; second, a coordinated response from the global supply chain. For example, the IEC 61249-2-21 standard stipulates that the bromine and chlorine contents of halogen-free materials must be less than 900 ppm each, and not more than 1500 ppm in total; and third, driven by both market demand and policy support, reducing halogen content while improving the overall performance of resins is a hot topic in industry research.

[0003] Chinese invention patent application CN110698639A discloses an alkali-soluble photosensitive resin and a preparation method thereof. The method comprises: mixing isocyanate, polyol, catalyst and polymerization inhibitor, reacting at a first reaction temperature to obtain an initial product; adding hydroxy acrylate to the initial product, reacting at a second reaction temperature to obtain a polyurethane acrylate intermediate; adding an acid anhydride compound to the polyurethane acrylate intermediate, reacting to obtain the alkali-soluble photosensitive resin, and preparing polyurethane acrylates of different molecular weights by adjusting the ratio of polyol and isocyanate and the molecular weight of the polyol used, thereby obtaining an alkali-soluble photosensitive resin with different hardness and adjustable performance. Although it does not contain halogen elements, the invention does not explore the chemical resistance, insulation and adhesion of the photosensitive resin. Summary of the Invention

[0004] A first aspect of the present invention provides a method for preparing a low-halogen alkali-soluble photosensitive resin, comprising the following steps:

[0005] The amino resin, alcohol olefin and catalyst A are added to a solvent and mixed to carry out an ether exchange reaction to obtain an initial etherification product;

[0006] adding peroxide to the initial etherification product to carry out epoxidation reaction to obtain an epoxy resin intermediate;

[0007] Adding an olefinic acid compound, catalyst B and a polymerization inhibitor to the epoxy resin intermediate to carry out a ring-opening esterification reaction to obtain an epoxy acrylate intermediate;

[0008] Acid anhydride is added to the epoxy acrylate intermediate to carry out a carboxylation reaction to obtain a low-halogen alkali-soluble photosensitive resin;

[0009] The peroxide does not contain halogen elements.

[0010] Optionally, the peroxide includes at least one of hydrogen peroxide, performic acid, peracetone, peracetic acid, tert-butyl perbenzoate, p-nitroperbenzoic acid, tert-butyl peroxide, isopropyl peroxide, and cyclohexene peroxide.

[0011] The ether exchange reaction satisfies at least one of the following conditions:

[0012] a. The temperature of the ether exchange reaction is 80-130° C.; b. The molar ratio of the ether bond in the amino resin to the alcohol olefin is 1:(0.8-1.0); c. The mass ratio of the amino resin to catalyst A is 100:(0.5-3); d. The mass ratio of the amino resin to the solvent is 100:(30-200).

[0013] Optionally, the ether exchange reaction satisfies conditions ad.

[0014] The epoxidation reaction satisfies at least one of the following conditions:

[0015] e. The temperature of the epoxidation reaction is 50-90° C.; f. The molar ratio of unsaturated double bonds to peroxide in the initial etherification product is 1:(0.7-1.0).

[0016] Optionally, the epoxidation reaction satisfies the ef condition.

[0017] The ring-opening esterification reaction satisfies at least one of the following conditions:

[0018] g. The temperature of the ring-opening esterification reaction is 90-130°C; h. The molar ratio of the epoxy group in the epoxy resin intermediate to the carboxyl group in the olefinic acid compound is 1:(0.8-1.0); i. The mass ratio of the epoxy resin intermediate to catalyst B is 100:(0.5-5); j. The mass ratio of the epoxy resin intermediate to the polymerization inhibitor is 1000:(1-20).

[0019] Optionally, the ring-opening esterification reaction satisfies the gj condition.

[0020] The carboxylation reaction satisfies at least one of the k1 conditions:

[0021] k, the temperature of the carboxylation reaction is 80-120° C.; l, the molar ratio of hydroxyl group to acid anhydride in the epoxy acrylate intermediate is 100:(10-100).

[0022] Optionally, the carboxylation reaction satisfies the k1 condition.

[0023] The amino resin includes a triazine ring structure.

[0024] Optionally, the amino resin includes at least one of methylated melamine formaldehyde resin, butylated melamine formaldehyde resin, phenylated melamine formaldehyde resin and mixed etherified melamine formaldehyde resin.

[0025] The catalyst A comprises at least one of toluenesulfonic acid, styrenesulfonic acid, aminosulfonic acid, phthalic acid, benzoic acid, phenylacetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid.

[0026] The catalyst B includes at least one of triphenylphosphine, tetrabutylammonium bromide and triethylamine.

[0027] The polymerization inhibitor includes at least one of hydroquinone, p-methylphenol, 2,4,6-trinitrophenol, and 2,6-di-tert-butyl-p-cresol.

[0028] The olefinic acid compound includes acrylic acid or methacrylic acid.

[0029] The acid anhydride includes at least one of tetrahydrophthalic anhydride, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride.

[0030] The solvent includes at least one of propylene glycol methyl ether acetate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, tripropylene glycol diacrylate, and dipropylene glycol diacrylate.

[0031] The alcohol olefin includes an unsaturated alcohol with a carbon chain length of 3-20.

[0032] Optionally, the alcohol olefin includes an unsaturated alcohol with a carbon chain length of 3-8.

[0033] In the ether exchange reaction, an amino resin containing a rigid triazine ring is used as the starting material. The rigid triazine ring in the molecule is connected by ether bonds or methylene bonds, and is cross-linked with subsequently introduced epoxy groups and acrylates to form a three-dimensional network, forming a triple highly cross-linked network structure, which effectively improves the initial heat resistance and mechanical strength of the resin; in the epoxidation reaction, a peroxide that does not contain halogen elements is selected to convert the carbon-carbon double bonds of alcohol and olefins into epoxy groups through free radical reactions, effectively improving the high reactivity and thermal stability of the epoxy resin intermediate; in the ring-opening esterification reaction, an olefinic acid compound is introduced, and the double bonds of acrylates are introduced into the resin to provide photocuring active sites, which are quickly cross-linked under UV light to form a dense network. At the same time, the highly branched structure obtained by the epoxidation reaction can increase the double bond distribution density, shorten the exposure time, and significantly improve the sensitivity of the resin; in the carboxylation reaction, carboxyl groups are further introduced. Through specific reaction conditions and raw material ratios, the molecular weight of the resin is effectively controlled and matched with the pH of the developer, effectively solving the alkali solubility of the resin while strengthening the intermolecular force through hydrogen bonds, further improving the acid and alkali resistance.

[0034] The second aspect of the present invention provides a solder resist ink, comprising: 40-70 parts of a low-halogen alkali-soluble photosensitive resin, 15-30 parts of an organic solvent, 20-30 parts of a filler, 1-5 parts of a photoinitiator, and 0.5-5 parts of an auxiliary agent;

[0035] The photoinitiator does not contain halogen elements.

[0036] The filler includes titanium dioxide and barium sulfate.

[0037] Optionally, the mass ratio of the titanium dioxide to barium sulfate is 1:(3-5).

[0038] The auxiliary agent includes a solvent-free polymer dispersant.

[0039] The organic solvent includes an ester solvent, which can be propylene glycol methyl ether acetate.

[0040] The low-halogen alkali-soluble photosensitive resin is added to the solder resist ink in an amount of not less than 40 wt %.

[0041] Optionally, the low-halogen alkali-soluble photosensitive resin is added to the solder resist ink in an amount of not less than 50 wt %.

[0042] Beneficial effects

[0043] 1. The present invention sequentially undergoes ether exchange reaction, epoxidation reaction, ring-opening esterification reaction, and carboxylation reaction, and the solder resist ink prepared from the alkali-soluble photosensitive resin has chemical resistance and high temperature and high humidity resistance.

[0044] 2. A halogen-free peroxide is used in the epoxidation reaction, and a halogen-free photoinitiator is used in the solder mask ink. While maintaining the chemical resistance, high temperature and high humidity resistance, and insulation properties of the solder mask ink prepared from the alkali-soluble photosensitive resin, the halogen content of the prepared alkali-soluble photosensitive resin can be reduced to below 10 ppm.

[0045] 3. By controlling the addition amount of low-halogen alkali-soluble photosensitive resin in the solder resist ink to be not less than 40wt%, the adhesion and insulation performance of the solder resist ink can be further improved.

[0046] 4. The reaction conditions of the present invention are mild, highly controllable, and easy to scale up for industrial production.

[0047] 5. The solder resist ink of the present invention has high sensitivity and high resolution performance. DETAILED DESCRIPTION

[0048] Example 1

[0049] A method for preparing a low-halogen alkali-soluble photosensitive resin:

[0050] 390.44 g of methylated melamine formaldehyde resin (Jining Juyue New Materials Co., Ltd., brand JY-303), 348.5 g of allyl alcohol, 4 g of p-toluenesulfonic acid, and 400 g of propylene glycol methyl ether acetate were added to a four-necked flask equipped with a power stirring rod, a condenser reflux tube, a thermometer, and a water separator. Dry gas was introduced before heating, and the temperature was slowly raised to 110° C. The reaction was continued for 5 h to slowly remove small alcohol molecules from the reaction system, and the ether exchange product was obtained by cooling; the temperature was slowly raised to 110° C. The temperature was raised to 65°C, and 510 g of 40% hydrogen peroxide solution was slowly added dropwise. After keeping the temperature for 2 hours, the lower oily liquid was collected. Then, 7 g of triphenylphosphine and 1 g of hydroquinone were added. After the temperature was raised to 90°C, 345.6 g of acrylic acid was added dropwise. The addition was completed within 1 hour. The temperature was continued to be raised to 110°C and the reaction was continued for 4 hours. Finally, 510 g of tetrahydrophthalic anhydride was added and the reaction was continued for 4 hours. The temperature was then lowered to room temperature (25°C) to obtain an alkali-soluble photosensitive resin for use in subsequent solder mask inks.

[0051] A solder resist ink comprises, by mass, 50 parts of alkali-soluble photosensitive resin, 21 parts of solvent, 25 parts of filler, 3 parts of photoinitiator, and 1 part of auxiliary agent.

[0052] The solvent is propylene glycol methyl ether acetate.

[0053] The filler is a compound of titanium dioxide and barium sulfate, with a mass ratio of 1:4.

[0054] The titanium dioxide is rutile titanium dioxide, purchased from Jiangxi Tianguang Chemical Co., Ltd., model number TR-33; the barium sulfate is precipitated barium sulfate, purchased from Yunfu Hongzhi New Materials Co., Ltd., model number CB-500.

[0055] The photoinitiator is photoinitiator 184.

[0056] The auxiliary agent is a solvent-free polymer dispersant purchased from Guangzhou Songwei Trading Co., Ltd., model number MHDISPER 6653.

[0057] Example 2

[0058] A method for preparing a low halogen alkali-soluble photosensitive resin: 412.5g of butylated melamine formaldehyde resin (Xiamen Aikema Chemical Co., Ltd., brand BR220), 504.72g 1,4-Pentadien-3-ol, 4g p-toluenesulfonic acid, and 500g dipropylene glycol diacrylate were added to a four-necked flask equipped with a powered stirring rod, a condenser reflux tube, a thermometer, and an n-heptane water separator. Dry gas was introduced before heating, and the temperature was slowly increased to 115°C. The reaction was continued for 6 hours to slowly remove small alcohol molecules from the reaction system, and then cooled to obtain an ether exchange product. The temperature was slowly increased to 75°C, and 1020g of a 40% by weight peroxyformic acid solution was slowly added dropwise. After holding the temperature for 3 hours, the lower oily liquid was collected. Then, 10g triphenylphosphine and 1.5g hydroquinone were added. After heating to 95°C, 604.8g of acrylic acid was added dropwise. The addition was completed within 1 hour, and the temperature was continued to 110°C for 4 hours. Finally, 912g of tetrahydrophthalic anhydride was added, the reaction was continued for 4 hours, and the temperature was cooled to room temperature (25°C) to obtain an alkali-soluble photosensitive resin for subsequent use in solder mask ink.

[0059] A solder resist ink comprises, by mass, 50 parts of alkali-soluble photosensitive resin, 21 parts of solvent, 25 parts of filler, 3 parts of photoinitiator, and 1 part of auxiliary agent.

[0060] The solvent is propylene glycol methyl ether acetate.

[0061] The filler is a compound of titanium dioxide and barium sulfate, with a mass ratio of 1:4.

[0062] The titanium dioxide is rutile titanium dioxide, purchased from Jiangxi Tianguang Chemical Co., Ltd., model number TR-33; the barium sulfate is precipitated barium sulfate, purchased from Yunfu Hongzhi New Materials Co., Ltd., model number CB-500.

[0063] The photoinitiator is photoinitiator 184.

[0064] The auxiliary agent is a solvent-free polymer dispersant purchased from Guangzhou Songwei Trading Co., Ltd., model number MHDISPER 6653.

[0065] Comparative Example 1

[0066] The specific implementation is the same as that of Example 1; the difference is that the hydrogen peroxide in Example 1 is replaced by the same molar proportion of m-chloroperbenzoic acid.

[0067] Comparative Example 2

[0068] The specific implementation is the same as that of Example 2; the difference is that the peroxyformic acid in Example 2 is replaced by chlorine peroxide in the same molar proportion.

[0069] Comparative Example 3

[0070] The specific implementation method is the same as Example 1; the difference is that the preparation method of the solder mask ink formula in Comparative Example 3 is: 40 parts of photosensitive alkali-soluble resin, 31 parts of solvent, 25 parts of filler, 3 parts of photoinitiator, and 1 part of auxiliary agent, in parts by mass.

[0071] Comparative Example 4

[0072] The specific implementation is the same as that of Example 1; the difference is that the photoinitiator 184 in Example 1 is replaced by 4-chlorobenzophenone.

[0073] Performance testing methods

[0074] 1. The halogen content of the photosensitive alkali-soluble resin in the examples and comparative examples was tested (GB / T37861-2019 Determination of halogen content of electronic and electrical products-Ion chromatography), and the results are recorded in Table 1.

[0075] 2. The raw materials of the above embodiment and comparative example were mixed and dispersed at high speed and stirred evenly. The mixture was ground into a particle size of less than 15 μm by a ball mill. The mixture was coated on a plastic carrier film by a comma coater and baked in an oven at 80°C for 5-10 minutes. The dry film thickness was controlled to be 50-75 μm. The obtained solder resist dry film was hot pressed on a 0.15 mm SLP board (similar to a carrier board). The vacuum time was 30 seconds, the pressing was carried out at 100°C for 30 seconds, and the DI exposure machine was 1000 mJ / cm 2 After exposure to the energy of 1.000W, the film was allowed to stand for half an hour, and then heat cured at 160°C for 60 minutes. The protective film was removed and the film was heated at 30°C and a pressure of 1.0 kg / cm 2 After developing in 1wt% sodium carbonate solution for 60s, its performance was tested and the results are recorded in Table 1.

[0076] 1. 100-grid adhesion test: After development, the dry solder mask films prepared in the examples and comparative examples were tested using the 100-grid test method. A grid of 0.4 × 0.4 mm was drawn on the surface of the dry solder mask films. The adhesive tape was firmly adhered to the grid and quickly torn off at 180°. The test was repeated three times at the same location to observe whether it fell off. If no peeling occurred, it was considered qualified; otherwise, it was considered unqualified.

[0077] 2. Insulation test: After development, the dry solder resist films obtained in the examples and comparative examples were subjected to a CAF test in accordance with the requirements of IPC-TM-6502.6.25B. The test steps were as follows: solder the test wires, clean and remove the solder residues, bake the test wires at 105°C for half an hour, and test the baked test wires at 100VDC as the initial insulation resistance, which is recorded as R1; place the test wires at 85°C, 85% RH, high humidity and high heat conditions for 596 hours, and then test the insulation resistance of the test wires at 100VDC as R2.

[0078] 3. Chemical resistance and stability

[0079] Alkali resistance test: After development, the solder mask dry films obtained in the above examples and comparative examples were immersed in a 10 wt% NaOH aqueous solution at 35°C for 10 minutes to observe whether the dry films fell off. If no falling occurred, the films were qualified; otherwise, they were unqualified. The results are recorded in Table 1.

[0080] Acid resistance test: After development, the solder resist dry films obtained in the above examples and comparative examples were immersed in a 10 wt % H 2 SO 4 solution at 35° C. for 10 minutes to observe whether the dry films fell off. If no falling occurred, the films were considered qualified; otherwise, they were considered unqualified. The results are recorded in Table 1.

[0081] High temperature and high humidity resistance: After development, the solder mask dry films obtained in the above examples and comparative examples were placed under 85°C, 85% RH damp heat conditions for 596 hours according to IPC-TM-650. The dry films were then observed. If the dry films did not fall off or crack, they were considered qualified. Otherwise, they were considered unqualified. The results are recorded in Table 1.

[0082] 4. Resolution Test: As a resolution evaluation standard, a negative mask with a 60µm via opening is used to confirm the cross-sectional shape of the solder resist opening. Judgment criteria: ① positive tapered structure ② inverted tapered structure ③ undercut structure.

[0083] Table 1

[0084]

Claims

1. A method for preparing a low-halogen alkali-soluble photosensitive resin, characterized in that: The method comprises the following steps: adding an amino resin, an alcohol olefin, and a catalyst A into a solvent, mixing them, and performing an ether exchange reaction to obtain an initial etherification product; adding a peroxide into the initial etherification product, performing an epoxidation reaction, and obtaining an epoxy resin intermediate; adding an olefinic acid compound, a catalyst B, and a polymerization inhibitor into the epoxy resin intermediate, performing a ring-opening esterification reaction, and obtaining an epoxy acrylate intermediate; Acid anhydride is added to the epoxy acrylate intermediate to carry out a carboxylation reaction to obtain a low-halogen alkali-soluble photosensitive resin; and the peroxide does not contain halogen elements.

2. The method for preparing the low-halogen alkali-soluble photosensitive resin according to claim 1, characterized in that: The amino resin includes a triazine ring structure.

3. The method for preparing the low-halogen alkali-soluble photosensitive resin according to claim 2, characterized in that: The ether exchange reaction satisfies at least one of the following conditions: a. The temperature of the ether exchange reaction is 80-130° C.; b, the molar ratio of ether bond to alcohol olefin in the amino resin is 1:(0.8-1.0); c. The mass ratio of the amino resin to the catalyst A is 100:(0.5-3); d. The mass ratio of the amino resin to the solvent is 100:(30-200).

4. The method for preparing the low-halogen alkali-soluble photosensitive resin according to claim 2, wherein: The epoxidation reaction satisfies at least one of conditions e and f: e. The epoxidation reaction temperature is 50-90° C.; f. The molar ratio of unsaturated double bonds in the initial etherification product to peroxide is 1:(0.7-1.0).

5. The method for preparing the low-halogen alkali-soluble photosensitive resin according to claim 2, wherein: The ring-opening esterification reaction satisfies at least one of the following conditions: g, the temperature of the ring-opening esterification reaction is 90-130°C; h, the molar ratio of the epoxy group in the epoxy resin intermediate to the carboxyl group in the olefinic acid compound is 1:(0.8-1.0); i, the mass ratio of the epoxy resin intermediate to catalyst B is 100:(0.5-5); j, the mass ratio of the epoxy resin intermediate to the polymerization inhibitor is 1000:(1-20).

6. The method for preparing the low-halogen alkali-soluble photosensitive resin according to claim 2, characterized in that: The carboxylation reaction satisfies at least one of the conditions k and l: k, the temperature of the carboxylation reaction is 80-120°C; 1. The molar ratio of hydroxyl group to acid anhydride in the epoxy acrylate intermediate is 100:(10-100).

7. The method for preparing the low-halogen alkali-soluble photosensitive resin according to claim 1, characterized in that: The catalyst A comprises at least one of toluenesulfonic acid, styrenesulfonic acid, aminosulfonic acid, phthalic acid, benzoic acid, phenylacetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid.

8. The method for preparing the low-halogen alkali-soluble photosensitive resin according to claim 1, characterized in that: The catalyst B includes at least one of triphenylphosphine, tetrabutylammonium bromide and triethylamine.

9. A solder resist ink, characterized in that: The components include: 40-70 parts of the low-halogen alkali-soluble photosensitive resin according to any one of claims 1 to 8, 15-30 parts of an organic solvent, 20-30 parts of a filler, 1-5 parts of a photoinitiator, and 0.5-5 parts of an auxiliary agent; the photoinitiator does not contain halogen elements.

10. The solder resist ink according to claim 9, characterized in that: The low-halogen alkali-soluble photosensitive resin is added to the solder resist ink in an amount of not less than 40 wt %.

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