Preparation method of alkali-soluble resin for PCB photoresist

Abstract

The invention relates to the technical field of PCB (Printed Circuit Board) photoresist materials, in particular to a preparation method of alkali-soluble resin for PCB photoresistance, which comprises the following steps: preparing raw materials and monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, initiators: benzoyl peroxide and azodiisobutyronitrile, a chain transfer agent: lauryl mercaptan, and a solvent: 1, 2-dichloroethane; the crosslinking auxiliary agent is N-hydroxymethyl acrylamide and a hindered amine light stabilizer, the solvent is a mixed solvent of toluene and acetone, and the monomer raw materials are subjected to reduced pressure distillation to remove impurities and moisture. According to the preparation method of the alkali-soluble resin for the PCB photoresist, the molecular weight and molecular weight distribution of the alkali-soluble resin can be accurately controlled by utilizing an active free radical polymerization technology, so that the alkali-soluble resin is higher in alkali solubility, higher in dissolution rate and capable of being rapidly and completely dissolved; and the developing efficiency and the developing precision in the manufacturing process of the PCB photoresist are greatly improved, so that the quality and the stability of a photoetching pattern are improved.

Description

Technical Field

[0001] The invention relates to the technical field of PCB photoresist materials, in particular to a method for preparing an alkali-soluble resin for PCB photoresist. Background Art

[0002] Alkali-soluble resin for PCB photoresist is a special resin material used in the photolithography process to manufacture printed circuit boards. It can form a uniform coating on the substrate by spin coating or other methods before exposure. During the exposure and development process, the unexposed part can be dissolved and removed by the alkaline solution, while the exposed part is retained to form a circuit pattern. Its specific function in the photolithography process is that when the ultraviolet light source irradiates the photoresist material, the photoinitiator will trigger a chemical reaction of the resin, causing the resin in the exposed area to undergo cross-linking or other chemical changes, changing its chemical and physical properties, making it insoluble in the alkaline developer, while the resin in the unexposed area can be dissolved by the alkaline solution, thereby transferring the circuit pattern on the mask to the PCB substrate.

[0003] In the process of using alkali-soluble resins for PCB photoresists in photolithography processing, traditional alkali-soluble resins for PCB photoresists have gradually exposed their limitations in terms of sensitivity, resolution, chemical resistance, and synergistic performance with other additives, making it difficult to meet the complex requirements of modern PCB manufacturing processes. For example, in the process of making fine circuits, insufficient resolution of PCB photoresists will lead to defects such as rough circuit edges and short circuits. In subsequent processes such as chemical etching and electroplating, if the chemical resistance of the alkali-soluble resin is poor, it will affect the quality and performance stability of the PCB. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing an alkali-soluble resin for PCB photoresist to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing an alkali-soluble resin for PCB photoresist, the method for preparing the alkali-soluble resin comprising the following steps:

[0006] 1) preparing raw materials, monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, initiator: benzoyl peroxide and azobisisobutyronitrile, chain transfer agent: dodecyl mercaptan, crosslinking aid: N-hydroxymethyl acrylamide and hindered amine light stabilizer, solvent: a mixed solvent of toluene and acetone, and removing impurities and moisture from the monomer raw materials by reduced pressure distillation;

[0007] 2) adding the above monomer raw materials and solvent into a reactor, wherein a gas protection device is installed on the reactor, and the raw materials are charged into the reactor with protective gas, and after the protective gas is charged, the reactor is started for heating and mixing, and initiators, crosslinking aids and chain transfer agents are added one by one during the stirring and mixing process;

[0008] 3) After the raw materials are heated and stirred in the reactor, the epoxy compound is added dropwise to the reaction solution, and the catalyst is added at the same time, and then the stirring and mixing are continued. After that, when the temperature of the reactor reaches the set value, this temperature is maintained to ensure that the polymerization reaction is fully carried out;

[0009] 4) After the reaction of the reaction liquid in the reactor is completed, the toluene in the reaction liquid is first removed by vacuum distillation, and then the reaction liquid is subjected to high-temperature extraction with an extractant, and then cooled to room temperature, and the reaction liquid is slowly poured into deionized water, stirred and precipitated, and then vacuum filtered and washed, and then vacuum dried to obtain the alkali-soluble resin semi-finished product;

[0010] 5) Physically blending the dried alkali-soluble resin semi-finished product with a plasticizer and a coupling agent, stirring in a high-speed stirrer, and then continuing to vacuum dry to obtain an alkali-soluble resin finished product.

[0011] In a further embodiment, the molar ratio of methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer is 3:2:1:1, and the mixing volume ratio of toluene and acetone in the mixed solvent is 2:1.

[0012] In a further embodiment, the protective gas introduced by the gas protection device installed on the reactor is nitrogen, the time for introducing nitrogen is 30 minutes, the flow rate of nitrogen injection is 18 mL / min, the heating temperature of the alkali-soluble resin in the reactor is 100°C, and the stirring speed of the reactor can be adaptively adjusted according to the mixed viscosity of the raw materials and the reaction progress at different stages of the reaction, with an adjustment range of 100-150 rpm, and the reaction time is 3-5 hours.

[0013] In a further embodiment, the vacuum distillation temperature is 110-120°C, the vacuum distillation pressure is 50kPa, the vacuum drying temperature of the reaction liquid is 70°C, the time is 7-9 hours, the vacuum drying temperature of the alkali-soluble resin semi-finished product, the plasticizer and the coupling agent is 50-70°C, and the drying time is 5 hours.

[0014] In a further embodiment, the extractant is prepared by mixing ethyl acetate and water, the volume ratio of the mixed solution is 3:1, and the extractant extracts the reaction solution 3 times.

[0015] In a further embodiment, the plasticizer is dibutyl phthalate, and the addition amount of the dibutyl phthalate is 10% of the mass of the alkali-soluble resin semi-finished product; the coupling agent is silane coupling agent KH-560, and the addition amount of the silane coupling agent KH-560 is 3% of the mass of the alkali-soluble resin semi-finished product; the stirring speed of mixing the alkali-soluble resin semi-finished product with the coupling agent and the plasticizer is 900 rpm, and the stirring time is 35 minutes.

[0016] In a further embodiment, the reactor is composed of a high-efficiency stirring mechanism, a precision thermometer, a condenser and a gas protection device.

[0017] In a further embodiment, the volume of the deionized water is 4-6 times that of the reaction solution, the reaction solution is filtered in the deionized water by a vacuum filtration device, and after the filtration is completed, the reaction solution is washed again with deionized water, and the number of washing times with the deionized water is 2 times.

[0018] In a further embodiment, the mass ratio of the epoxy compound to the reaction liquid is 1:5, the epoxy compound is one or more of dioxane, epichlorohydrin and bisphenol A epoxy resin, the catalyst is triethylamine, and the amount of triethylamine added is 3% of the total mass of the reaction liquid.

[0019] In a further embodiment, the water content of the alkali-soluble resin after vacuum drying is less than 0.5% of the total mass of the alkali-soluble resin.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, the alkali-soluble resin utilizes active free radical polymerization technology, so that the alkali-soluble resin can accurately control the molecular weight and molecular weight distribution of the resin. Compared with the molecular weight distribution in the traditional polymerization method, it is narrower, and the problem of uneven resin performance caused by excessive molecular weight is prevented. The alkali-soluble resin has stronger alkali solubility and higher dissolution rate, and can be dissolved quickly and completely, which greatly improves the development efficiency and accuracy in the PCB photoresist manufacturing process, thereby improving the quality and stability of the photolithography pattern;

[0022] 2. In the present invention, the alkali-soluble resin is prepared by chemical modification, and epoxy groups are introduced during the preparation process of the alkali-soluble resin, which can effectively balance the alkali solubility of the resin with other properties, so that the resin can significantly improve the heat resistance, moisture resistance and chemical stability while maintaining good alkali solubility, and can better adapt the alkali-soluble resin for PCB photoresist to the high temperature, high humidity and contact with chemical reagents in the manufacturing process, so that the alkali-soluble resin has excellent tolerance, ensuring the quality stability of the alkali-soluble resin for PCB photoresist in the subsequent processing process;

[0023] 3. In the present invention, the alkali-soluble resin is mixed with auxiliary materials such as an initiator, a chain transfer agent, a plasticizer, a coupling agent and an additive, which further improves the flexibility of the resin and the adhesion to the substrate, improves the applicability and reliability of the alkali-soluble resin in the PCB photoresist manufacturing process, reduces the risk of rupture and peeling of the film layer on the surface of the PCB photoresist, and helps to improve the manufacturing quality and production efficiency of the PCB photoresist. In addition, each material has excellent compatibility and can form a uniform, stable and high-performance photoresist system, ensuring good coating performance, adhesion and long-term stability of the photoresist film on the PCB photoresist substrate;

[0024] 4. In the present invention, the alkali-soluble resin is purified during its preparation, and the purification steps include reduced-pressure distillation, extraction and vacuum drying. The purification treatment of the alkali-soluble resin can effectively remove residual monomers, initiators and other impurities, thereby improving the purity and performance stability of the resin, reducing the adverse effects on the quality of PCB photoresist products, and improving the product quality of PCB photoresist. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a block diagram of the specific steps of the method for preparing the alkali-soluble resin of the present invention;

[0026] Figure 2 The present invention is a flowchart of the preparation process of the alkali-soluble resin. DETAILED DESCRIPTION

[0027] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Comparative Example

[0029] This embodiment provides a method for preparing an alkali-soluble resin for PCB photoresist, and the method for preparing the alkali-soluble resin comprises the following steps:

[0030] The alkali soluble resin is prepared by polymerization of:

[0031] 30-40 parts of methacrylic acid, 20-30 parts of styrene, 5-10 parts of hydroxyethyl acrylate, 3-8 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 1-3 parts of benzoyl peroxide, 0.5-2 parts of azobisisobutyronitrile, 0.5-1.5 parts of dodecyl mercaptan, 0.5-2 parts of N-hydroxymethyl acrylamide, 0.1-0.5 parts of hindered amine light stabilizer and 100-130 parts of a mixed solvent of toluene and acetone;

[0032] Accurately weigh 35 parts of methacrylic acid, 28 parts of styrene, 9 parts of hydroxyethyl acrylate, 7 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 3 parts of benzoyl peroxide, 1.5 parts of azobisisobutyronitrile, 1.5 parts of dodecyl mercaptan, 1.5 parts of N-hydroxymethyl acrylamide, 0.5 parts of hindered amine light stabilizer and 120 parts of a mixed solvent of toluene and acetone;

[0033] The above-mentioned alkali-soluble resin is prepared by the following method:

[0034] 1) preparing raw materials, monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, initiator: benzoyl peroxide and azobisisobutyronitrile, chain transfer agent: dodecyl mercaptan, crosslinking aid: N-hydroxymethyl acrylamide and hindered amine light stabilizer, solvent: a mixed solvent of toluene and acetone, and removing impurities and moisture from the monomer raw materials by reduced pressure distillation;

[0035] 2) adding the above monomer raw materials and solvent into a reactor, which is equipped with a gas protection device, and charging the raw materials into the reactor with protective gas. After the protective gas is charged, the reactor is started for heating and mixing, and initiators, crosslinking aids and chain transfer agents are added one by one during the stirring and mixing process;

[0036] 3) After the raw materials are heated and stirred in the reactor, the epoxy compound is added dropwise to the reaction solution, and the catalyst is added at the same time, and then the stirring and mixing are continued. After that, when the temperature of the reactor reaches the set value, this temperature is maintained to ensure that the polymerization reaction is fully carried out;

[0037] 4) After the reaction of the reaction liquid in the reactor is completed, the toluene in the reaction liquid is first removed by vacuum distillation, and then the reaction liquid is subjected to high-temperature extraction with an extractant, and then cooled to room temperature, and the reaction liquid is slowly poured into deionized water, stirred and precipitated, and then vacuum filtered and washed, and then vacuum dried to obtain an alkali-soluble resin semi-finished product;

[0038] 5) Physically blending the dried alkali-soluble resin semi-finished product with a plasticizer and a coupling agent, stirring in a high-speed stirrer, and then continuing to vacuum dry to obtain an alkali-soluble resin finished product.

[0039] Optionally, the alkali-soluble resin prepared above is prepared into a photosensitive resin composition (i.e., the raw material of the photoresist) in the following proportions: 20% alkali-soluble resin, 13% blue-green pigment mixed with phthalocyanine green pigment with index number C.I74260 and phthalocyanine blue pigment with index number C.I74160, 22% dispersion resin with the trade name TPU5778, 15% monomer dipentaerythritol hexaacrylate, 5% 1-hydroxy-cyclohexyl-phenyl ketone, and 25% propylene glycol methyl ether acetate.

[0040] The components and contents of the above-mentioned photosensitive resin composition are within the scope of the prior art. This embodiment is only applicable to the photosensitive resin composition for experimentation, and other components and contents of the components may also be used.

[0041] A portion of the above-mentioned photosensitive resin composition was added to a 0.3% sodium hydroxide solution to perform an alkali solubility test; the remaining portion was coated on a glass substrate by a coating machine to form a photosensitive resin film layer, and then the glass substrate coated with the alkali-soluble resin was placed in a PCB photoresist exposure test device to perform an exposure test under 365nm ultraviolet light; the photosensitive resin composition was made into a film, and was immersed in an etching solution (such as a cupric chloride solution) and an electroplating solution (such as a copper sulfate solution) commonly used for PCB photoresist for 24 hours, and its chemical resistance was evaluated by observing indicators such as the integrity, weight change, and surface morphology of the film; the photosensitive resin composition was mixed with a variety of common PCB photoresist additives in different proportions, and the dispersion state and particle size distribution of the mixture were observed using an optical microscope, a particle size analyzer, and other equipment; a standard sample made of resin was tested for tensile strength and hardness using a material strength testing machine, and the test results are shown in Table 1.

[0042] Example 1

[0043] A method for preparing an alkali-soluble resin for PCB photoresist, the method for preparing the alkali-soluble resin comprising the following steps:

[0044] The alkali soluble resin is prepared by polymerization of:

[0045] 30-40 parts of methacrylic acid, 20-30 parts of styrene, 5-10 parts of hydroxyethyl acrylate, 3-8 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 1-3 parts of benzoyl peroxide, 0.5-2 parts of azobisisobutyronitrile, 0.5-1.5 parts of dodecyl mercaptan, 0.5-2 parts of N-hydroxymethyl acrylamide, 0.1-0.5 parts of hindered amine light stabilizer and 100-130 parts of a mixed solvent of toluene and acetone;

[0046] Accurately weigh 35 parts of methacrylic acid, 28 parts of styrene, 9 parts of hydroxyethyl acrylate, 6 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 2 parts of benzoyl peroxide, 1 part of azobisisobutyronitrile, 1.2 parts of dodecyl mercaptan, 1.2 parts of N-hydroxymethyl acrylamide, 0.4 parts of hindered amine light stabilizer and 110 parts of a mixed solvent of toluene and acetone;

[0047] The above-mentioned alkali-soluble resin is prepared by the following method:

[0048] 1) preparing raw materials, monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, initiator: benzoyl peroxide and azobisisobutyronitrile, chain transfer agent: dodecyl mercaptan, crosslinking aid: N-hydroxymethyl acrylamide and hindered amine light stabilizer, solvent: a mixed solvent of toluene and acetone, and removing impurities and moisture from the monomer raw materials by reduced pressure distillation;

[0049] 2) adding the above monomer raw materials and solvent into a reactor, which is equipped with a gas protection device, and charging the raw materials into the reactor with protective gas. After the protective gas is charged, the reactor is started for heating and mixing, and initiators, crosslinking aids and chain transfer agents are added one by one during the stirring and mixing process;

[0050] 3) After the raw materials are heated and stirred in the reactor, the epoxy compound is added dropwise to the reaction solution, and the catalyst is added at the same time, and then the stirring and mixing are continued. After that, when the temperature of the reactor reaches the set value, this temperature is maintained to ensure that the polymerization reaction is fully carried out;

[0051] 4) After the reaction of the reaction liquid in the reactor is completed, the toluene in the reaction liquid is first removed by vacuum distillation, and then the reaction liquid is subjected to high-temperature extraction with an extractant, and then cooled to room temperature, and the reaction liquid is slowly poured into deionized water, stirred and precipitated, and then vacuum filtered and washed, and then vacuum dried to obtain an alkali-soluble resin semi-finished product;

[0052] 5) Physically blending the dried alkali-soluble resin semi-finished product with a plasticizer and a coupling agent, stirring in a high-speed stirrer, and then continuing to vacuum dry to obtain an alkali-soluble resin finished product.

[0053] Optionally, the alkali-soluble resin prepared above is prepared into a photosensitive resin composition (i.e., the raw material of the photoresist) in the following proportions: 20% alkali-soluble resin, 13% blue-green pigment mixed with phthalocyanine green pigment with index number C.I74260 and phthalocyanine blue pigment with index number C.I74160, 22% dispersion resin with the trade name TPU5778, 15% monomer dipentaerythritol hexaacrylate, 5% 1-hydroxy-cyclohexyl-phenyl ketone, and 25% propylene glycol methyl ether acetate.

[0054] The components and contents of the above-mentioned photosensitive resin composition are within the scope of the prior art. This embodiment is only applicable to the photosensitive resin composition for experimentation, and other components and contents of the components may also be used.

[0055] A portion of the above-mentioned photosensitive resin composition was added to a 0.3% sodium hydroxide solution to perform an alkali solubility test; the remaining portion was coated on a glass substrate by a coating machine to form a photosensitive resin film layer, and then the glass substrate coated with the alkali-soluble resin was placed in a PCB photoresist exposure test device to perform an exposure test under 365nm ultraviolet light; the photosensitive resin composition was made into a film, and was immersed in an etching solution (such as a cupric chloride solution) and an electroplating solution (such as a copper sulfate solution) commonly used for PCB photoresist for 24 hours, and its chemical resistance was evaluated by observing indicators such as the integrity, weight change, and surface morphology of the film; the photosensitive resin composition was mixed with a variety of common PCB photoresist additives in different proportions, and the dispersion state and particle size distribution of the mixture were observed using an optical microscope, a particle size analyzer, and other equipment; a standard sample made of resin was tested for tensile strength and hardness using a material strength testing machine, and the test results are shown in Table 1.

[0056] Example 2

[0057] A method for preparing an alkali-soluble resin for PCB photoresist, the method for preparing the alkali-soluble resin comprising the following steps:

[0058] The alkali soluble resin is prepared by polymerization of:

[0059] 30-40 parts of methacrylic acid, 20-30 parts of styrene, 5-10 parts of hydroxyethyl acrylate, 3-8 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 1-3 parts of benzoyl peroxide, 0.5-2 parts of azobisisobutyronitrile, 0.5-1.5 parts of dodecyl mercaptan, 0.5-2 parts of N-hydroxymethyl acrylamide, 0.1-0.5 parts of hindered amine light stabilizer and 100-130 parts of a mixed solvent of toluene and acetone;

[0060] Accurately weigh 35 parts of methacrylic acid, 28 parts of styrene, 9 parts of hydroxyethyl acrylate, 3 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 1.5 parts of benzoyl peroxide, 0.8 parts of azobisisobutyronitrile, 0.8 parts of dodecyl mercaptan, 0.8 parts of N-hydroxymethyl acrylamide, 0.3 parts of hindered amine light stabilizer and 100 parts of a mixed solvent of toluene and acetone;

[0061] The above-mentioned alkali-soluble resin is prepared by the following method:

[0062] 1) preparing raw materials, monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, initiator: benzoyl peroxide and azobisisobutyronitrile, chain transfer agent: dodecyl mercaptan, crosslinking aid: N-hydroxymethyl acrylamide and hindered amine light stabilizer, solvent: a mixed solvent of toluene and acetone, and removing impurities and moisture from the monomer raw materials by reduced pressure distillation;

[0063] 2) adding the above monomer raw materials and solvent into a reactor, which is equipped with a gas protection device, and charging the raw materials into the reactor with protective gas. After the protective gas is charged, the reactor is started for heating and mixing, and initiators, crosslinking aids and chain transfer agents are added one by one during the stirring and mixing process;

[0064] 3) After the raw materials are heated and stirred in the reactor, the epoxy compound is added dropwise to the reaction solution, and the catalyst is added at the same time, and then the stirring and mixing are continued. After that, when the temperature of the reactor reaches the set value, this temperature is maintained to ensure that the polymerization reaction is fully carried out;

[0065] 4) After the reaction of the reaction liquid in the reactor is completed, the toluene in the reaction liquid is first removed by vacuum distillation, and then the reaction liquid is subjected to high-temperature extraction with an extractant, and then cooled to room temperature, and the reaction liquid is slowly poured into deionized water, stirred and precipitated, and then vacuum filtered and washed, and then vacuum dried to obtain an alkali-soluble resin semi-finished product;

[0066] 5) Physically blending the dried alkali-soluble resin semi-finished product with a plasticizer and a coupling agent, stirring in a high-speed stirrer, and then continuing to vacuum dry to obtain an alkali-soluble resin finished product.

[0067] Optionally, the alkali-soluble resin prepared above is prepared into a photosensitive resin composition (i.e., the raw material of the photoresist) in the following proportions: 20% alkali-soluble resin, 13% blue-green pigment mixed with phthalocyanine green pigment with index number C.I74260 and phthalocyanine blue pigment with index number C.I74160, 22% dispersion resin with the trade name TPU5778, 15% monomer dipentaerythritol hexaacrylate, 5% 1-hydroxy-cyclohexyl-phenyl ketone, and 25% propylene glycol methyl ether acetate.

[0068] The components and contents of the above-mentioned photosensitive resin composition are within the scope of the prior art. This embodiment is only applicable to the photosensitive resin composition for experimentation, and other components and contents of the components may also be used.

[0069] A portion of the above-mentioned photosensitive resin composition was added to a 0.3% sodium hydroxide solution to perform an alkali solubility test; the remaining portion was coated on a glass substrate by a coating machine to form a photosensitive resin film layer, and then the glass substrate coated with the alkali-soluble resin was placed in a PCB photoresist exposure test device to perform an exposure test under 365nm ultraviolet light; the photosensitive resin composition was made into a film, and was immersed in an etching solution (such as a cupric chloride solution) and an electroplating solution (such as a copper sulfate solution) commonly used for PCB photoresist for 24 hours, and its chemical resistance was evaluated by observing indicators such as the integrity, weight change, and surface morphology of the film; the photosensitive resin composition was mixed with a variety of common PCB photoresist additives in different proportions, and the dispersion state and particle size distribution of the mixture were observed using an optical microscope, a particle size analyzer, and other equipment; a standard sample made of resin was tested for tensile strength and hardness using a material strength testing machine, and the test results are shown in Table 1.

[0070] Example 3

[0071] A method for preparing an alkali-soluble resin for PCB photoresist, the method for preparing the alkali-soluble resin comprising the following steps:

[0072] The alkali soluble resin is prepared by polymerization of:

[0073] 30-40 parts of methacrylic acid, 20-30 parts of styrene, 5-10 parts of hydroxyethyl acrylate, 3-8 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 1-3 parts of benzoyl peroxide, 0.5-2 parts of azobisisobutyronitrile, 0.5-1.5 parts of dodecyl mercaptan, 0.5-2 parts of N-hydroxymethyl acrylamide, 0.1-0.5 parts of hindered amine light stabilizer and 100-130 parts of a mixed solvent of toluene and acetone;

[0074] Accurately weigh 35 parts of methacrylic acid, 28 parts of styrene, 9 parts of hydroxyethyl acrylate, 2 parts of maleic anhydride-perfluoroalkyl vinyl ether copolymer, 0.8 parts of benzoyl peroxide, 0.6 parts of azobisisobutyronitrile, 0.5 parts of dodecyl mercaptan, 0.5 parts of N-hydroxymethyl acrylamide, 0.2 parts of hindered amine light stabilizer and 85 parts of a mixed solvent of toluene and acetone;

[0075] The above-mentioned alkali-soluble resin is prepared by the following method:

[0076] 1) preparing raw materials, monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, initiator: benzoyl peroxide and azobisisobutyronitrile, chain transfer agent: dodecyl mercaptan, crosslinking aid: N-hydroxymethyl acrylamide and hindered amine light stabilizer, solvent: a mixed solvent of toluene and acetone, and removing impurities and moisture from the monomer raw materials by reduced pressure distillation;

[0077] 2) adding the above monomer raw materials and solvent into a reactor, which is equipped with a gas protection device, and charging the raw materials into the reactor with protective gas. After the protective gas is charged, the reactor is started for heating and mixing, and initiators, crosslinking aids and chain transfer agents are added one by one during the stirring and mixing process;

[0078] 3) After the raw materials are heated and stirred in the reactor, the epoxy compound is added dropwise to the reaction solution, and the catalyst is added at the same time, and then the stirring and mixing are continued. After that, when the temperature of the reactor reaches the set value, this temperature is maintained to ensure that the polymerization reaction is fully carried out;

[0079] 4) After the reaction of the reaction liquid in the reactor is completed, the toluene in the reaction liquid is first removed by vacuum distillation, and then the reaction liquid is subjected to high-temperature extraction with an extractant, and then cooled to room temperature, and the reaction liquid is slowly poured into deionized water, stirred and precipitated, and then vacuum filtered and washed, and then vacuum dried to obtain an alkali-soluble resin semi-finished product;

[0080] 5) Physically blending the dried alkali-soluble resin semi-finished product with a plasticizer and a coupling agent, stirring in a high-speed stirrer, and then continuing to vacuum dry to obtain an alkali-soluble resin finished product.

[0081] Optionally, the alkali-soluble resin prepared above is prepared into a photosensitive resin composition (i.e., the raw material of the photoresist) in the following proportions: 20% alkali-soluble resin, 13% blue-green pigment mixed with phthalocyanine green pigment with index number C.I74260 and phthalocyanine blue pigment with index number C.I74160, 22% dispersion resin with the trade name TPU5778, 15% monomer dipentaerythritol hexaacrylate, 5% 1-hydroxy-cyclohexyl-phenyl ketone, and 25% propylene glycol methyl ether acetate.

[0082] The components and contents of the above-mentioned photosensitive resin composition are within the scope of the prior art. This embodiment is only applicable to the photosensitive resin composition for experimentation, and other components and contents of the components may also be used.

[0083] A portion of the above-mentioned photosensitive resin composition was added to a 0.3% sodium hydroxide solution to perform an alkali solubility test; the remaining portion was coated on a glass substrate by a coating machine to form a photosensitive resin film layer, and then the glass substrate coated with the alkali-soluble resin was placed in a PCB photoresist exposure test device to perform an exposure test under 365nm ultraviolet light; the photosensitive resin composition was made into a film, and was immersed in an etching solution (such as a cupric chloride solution) and an electroplating solution (such as a copper sulfate solution) commonly used for PCB photoresist for 24 hours, and its chemical resistance was evaluated by observing indicators such as the integrity, weight change, and surface morphology of the film; the photosensitive resin composition was mixed with a variety of common PCB photoresist additives in different proportions, and the dispersion state and particle size distribution of the mixture were observed using an optical microscope, a particle size analyzer, and other equipment; a standard sample made of resin was tested for tensile strength and hardness using a material strength testing machine, and the test results are shown in Table 1.

[0084] Table 1 is a performance comparison table of alkali soluble resins

[0085] Group / Performance Alkali solubility (g / min) <![CDATA[Photosensitivity (mJ / cm 2 )]]> Chemical resistance compatibility strength Comparative Example 2.56 70 5.56％ I 34、76 Example 1 2.24 56 8.14％ I 30、72 Example 2 1.82 48 9.89％ II 28、69 Example 3 1.57 40 10.26％ II 25、64

[0086] Among them, in the above table, compatibility is divided into I (good compatibility), II (average compatibility) and III (poor compatibility), and strength refers to tensile strength (unit: MPa) and Shore hardness (unit: HD).

[0087] It can be seen from Table 1 that the performance of the photosensitive resin compositions of Examples 1, 2 and 3 is significantly improved compared with the photosensitive resin composition of the comparative example.

[0088] Table 2 shows other performance data of alkali-soluble resin:

[0089] Group / Performance Resolution(μm) Adhesion Water resistance Heat resistance(℃) Comparative Example 40.25 0 I 130.5 Example 1 36.56 1 II 145.6 Example 2 32.58 1 II 167.3 Example 3 29.56 1 III 182.6

[0090] Among them, resolution refers to the minimum pattern size that the resin can form after exposure and development. It is generally measured by a cross-hatch test or a tape peeling test, that is, after the cross-hatch or tape peeling, the adhesion between the resin layer and the copper foil is good, without obvious shedding or peeling. Among them, level 0 represents obvious shedding and peeling, and level 1 represents no obvious shedding and peeling. Water resistance refers to the fact that after a humid environment or a boiling test, the performance of the resin, such as insulation resistance and adhesion, should change slightly. For example, after being placed in an environment of 40°C and 95% relative humidity for 72 hours, the insulation resistance does not drop by more than one order of magnitude. It is divided into three levels, among which level I represents a large insulation resistance drop, level II represents a small insulation resistance drop, and level III represents a negligible insulation resistance drop. Heat resistance refers to the temperature at which the resin changes from a glassy state to a highly elastic state, and the higher the required temperature, the better its heat resistance.

[0091] It can be seen from Table 2 that the performance of the photosensitive resin compositions of Examples 1, 2 and 3 is significantly improved compared to the photosensitive resin composition of the comparative example.

[0092] Example 4

[0093] Reference Figure 1-Figure 2 This embodiment provides a method for preparing an alkali-soluble resin for PCB photoresist, and the method for preparing the alkali-soluble resin comprises the following steps:

[0094] 1) Prepare raw materials, monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, the fluorine element contained in it can significantly reduce the surface energy of the resin, improve the water resistance and chemical corrosion resistance of the resin and the compatibility with other components in the photoresist, and the maleic anhydride group can participate in the polymerization reaction to enhance the cross-linking performance of the resin, initiator: benzoyl peroxide and azobisisobutyronitrile, chain transfer agent: dodecyl mercaptan, which can effectively control the molecular weight distribution of the polymer, improve the alkali solubility and dissolution rate of the alkali-soluble resin, cross-linking aid: N-hydroxy Methacrylamide and hindered amine light stabilizers, as crosslinking aids, can form a crosslinking network in the resin system, further improving the mechanical properties and chemical resistance of the resin. Solvent: a mixture of toluene and acetone. This solvent system can ensure that each raw material has good solubility and reactivity. The monomer raw material is distilled under reduced pressure to remove impurities and moisture. By removing impurities and moisture in the raw materials and additives by distillation under reduced pressure in advance, the quality of the alkali-soluble resin prepared and processed later can be improved, and the adhesion of the alkali-soluble resin caused by moisture and impurities can be prevented from being reduced, thereby affecting its performance.

[0095] 2) adding the above monomer raw materials and solvent into a reactor, which is equipped with a gas protection device, and charging the raw materials into the reactor with protective gas. After the charging of the protective gas is completed, the reactor is started for heating and mixing. Initiators, crosslinking aids and chain transfer agents are added one by one during the stirring and mixing process. Nitrogen gas for protection is charged into the reactor to exclude oxygen in the reaction, prevent oxygen from interfering with the polymerization reaction, and improve the polymer of the alkali-soluble resin to be able to mix and react more fully;

[0096] 3) After the raw materials are heated and stirred in the reactor, an epoxy compound is added dropwise to the reaction solution to react the epoxy group with the acidic functional group in the resin prepolymer, introduce the epoxy group, enhance the heat resistance, moisture resistance and chemical stability of the resin, and maintain good alkali solubility, and at the same time add a catalyst, and then continue to stir and mix. After that, when the temperature of the reactor reaches the set value, maintain this temperature to ensure that the polymerization reaction is fully carried out. During the heating and heat preservation period, the temperature of the reactor is kept stable by a condenser to prevent the influence of temperature fluctuations on the reaction process and product performance;

[0097] 4) After the reaction of the reaction liquid in the reactor is completed, the toluene in the reaction liquid is first removed by reduced pressure distillation, and then the reaction liquid is subjected to high-temperature extraction with an extractant, and then cooled to room temperature, and the reaction liquid is slowly poured into deionized water, stirred and precipitated, and then vacuum filtered and washed, and then vacuum dried to obtain an alkali-soluble resin semi-finished product, which can effectively remove residual monomers, initiators and other impurities, improve the purity and performance stability of the resin, and reduce the adverse effects on product quality;

[0098] 5) Physically blending the dried alkali-soluble resin semi-finished product with a plasticizer and a coupling agent, stirring in a high-speed stirrer, and then continuing to vacuum dry to obtain an alkali-soluble resin finished product, and by adding a plasticizer and a coupling agent, the functional additives are evenly dispersed in the alkali-soluble resin semi-finished product, and the flexibility, adhesion and other properties of the alkali-soluble resin are further improved to obtain a final alkali-soluble resin product for PCB photoresist, and the strength of the alkali-soluble resin is improved.

[0099] The molar ratio of methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer is 3:2:1:1, and the mixing volume ratio of toluene and acetone in the mixed solvent is 2:1.

[0100] The protective gas introduced by the gas protection device installed on the reactor is nitrogen. The time of nitrogen introduction is 30 minutes. The flow rate of nitrogen injection is 18mL / min. The heating temperature of the alkali-soluble resin in the reactor is 100°C. The stirring speed of the reactor can be adaptively adjusted according to the mixed viscosity of the raw materials and the reaction progress at different stages of the reaction. The adjustment range is 100-150 rpm, and the reaction time is 3-5 hours.

[0101] The vacuum distillation temperature is 110-120°C, the vacuum distillation pressure is 50kPa, the vacuum drying temperature of the reaction liquid is 70°C, the time is 7-9 hours, the vacuum drying temperature of the alkali-soluble resin semi-finished product, the plasticizer and the coupling agent is 50-70°C, and the drying time is 5 hours.

[0102] The extractant is prepared by mixing ethyl acetate and water, the volume ratio of the mixed solution is 3:1, the extractant extracts the reaction solution 3 times, the volume of deionized water is 4-6 times that of the reaction solution, the reaction solution is filtered in the deionized water through a vacuum filtration device, and after the filtration is completed, the reaction solution is washed again with deionized water, and the number of washing times with deionized water is 2 times. The high-temperature extraction of the reaction solution by the extractant and the filtration and washing with deionized water can effectively remove impurities appearing in the reaction process of the alkali-soluble resin, thereby reducing the quality impact of the impurities on the alkali-soluble resin finished product.

[0103] The plasticizer is dibutyl phthalate, and the added amount of dibutyl phthalate is 10% of the mass of the alkali-soluble resin semi-finished product. The coupling agent is silane coupling agent KH-560, and the added amount of silane coupling agent KH-560 is 3% of the mass of the alkali-soluble resin semi-finished product. The stirring speed of mixing the alkali-soluble resin semi-finished product with the coupling agent and the plasticizer is 900 rpm, and the stirring time is 35 minutes. By mixing the plasticizer and the coupling agent with the alkali-soluble resin, the flexibility, adhesion and other properties of the resin are further improved, and the final alkali-soluble resin product for PCB photoresist is obtained.

[0104] The reactor is composed of an efficient stirring mechanism, a precision thermometer, a condenser and a gas protection device. The precision thermometer is used to detect the temperature inside the reactor. The condenser is used to condense and cool down the reactor when the temperature is too high, thereby keeping the temperature of the reactor within a range suitable for the preparation of alkali-soluble resins, thereby improving the accuracy and efficiency of the preparation. The gas protection device is used to fill the reactor with protective gas to reduce the oxygen content, thereby reducing the oxidation of the alkali-soluble resin during the reaction process and ensuring the quality of the prepared alkali-soluble resin.

[0105] The mass ratio of the epoxy compound to the reaction liquid is 1:5, the epoxy compound is one or more of dioxane, epichlorohydrin and bisphenol A epoxy resin, the catalyst is triethylamine, and the added amount of triethylamine is 3% of the total mass of the reaction liquid. The epoxy compound has good heat resistance, mechanical strength and chemical stability, and the cured resin has excellent comprehensive properties, can effectively improve the hardness, heat resistance and chemical corrosion resistance of the alkali-soluble resin, and can improve the performance of the alkali-soluble resin.

[0106] The water content of the alkali-soluble resin after vacuum drying is lower than 0.5% of the total mass of the alkali-soluble resin. By reducing the water content of the alkali-soluble resin, the dimensional stability of the alkali-soluble resin during exposure and development is enhanced, and the internal chemical environment is more stable. At the same time, the reduction in moisture reduces the possibility of chemical reaction between the alkali-soluble resin and corrosive substances, thereby ensuring the stability of the chemical properties of the alkali-soluble resin.

[0107] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an alkali-soluble resin for PCB photoresist, characterized in that: The preparation method of the alkali-soluble resin comprises the following steps: 1) preparing raw materials, monomer raw materials: methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer, initiator: benzoyl peroxide and azobisisobutyronitrile, chain transfer agent: dodecyl mercaptan, crosslinking aid: N-hydroxymethyl acrylamide and hindered amine light stabilizer, solvent: a mixed solvent of toluene and acetone, and removing impurities and moisture from the monomer raw materials by reduced pressure distillation; 2) adding the above monomer raw materials and solvent into a reactor, wherein a gas protection device is installed on the reactor, and the raw materials are charged into the reactor with protective gas, and after the protective gas is charged, the reactor is started for heating and mixing, and initiators, crosslinking aids and chain transfer agents are added one by one during the stirring and mixing process; 3) After the raw materials are heated and stirred in the reactor, the epoxy compound is added dropwise to the reaction solution, and the catalyst is added at the same time, and then the stirring and mixing are continued. After that, when the temperature of the reactor reaches the set value, this temperature is maintained to ensure that the polymerization reaction is fully carried out; 4) After the reaction of the reaction liquid in the reactor is completed, the toluene in the reaction liquid is first removed by vacuum distillation, and then the reaction liquid is subjected to high-temperature extraction with an extractant, and then cooled to room temperature, and the reaction liquid is slowly poured into deionized water, stirred and precipitated, and then vacuum filtered and washed, and then vacuum dried to obtain the alkali-soluble resin semi-finished product; 5) Physically blending the dried alkali-soluble resin semi-finished product with a plasticizer and a coupling agent, stirring in a high-speed stirrer, and then continuing to vacuum dry to obtain an alkali-soluble resin finished product.

2. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The molar ratio of the methacrylic acid, styrene, hydroxyethyl acrylate and maleic anhydride-perfluoroalkyl vinyl ether copolymer is 3:2:1:1, and the mixed volume ratio of toluene and acetone in the mixed solvent is 2:

1.

3. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The protective gas introduced by the gas protection device installed on the reactor is nitrogen, the time of introducing nitrogen is 30 minutes, the flow rate of nitrogen rushing is 18mL / min, the heating temperature of the alkali-soluble resin in the reactor is 100°C, and the stirring speed of the reactor can be adaptively adjusted according to the mixed viscosity of the raw materials and the reaction progress at different stages of the reaction, the adjustment range is 100-150 rpm, and the reaction time is 3-5 hours.

4. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The vacuum distillation temperature is 110-120°C, the vacuum distillation pressure is 50kPa, the vacuum drying temperature of the reaction solution is 70°C, the time is 7-9 hours, the vacuum drying temperature of the alkali-soluble resin semi-finished product, the plasticizer and the coupling agent is 50-70°C, and the drying time is 5 hours.

5. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The extractant is prepared by mixing ethyl acetate and water, the volume ratio of the mixed solution is 3:1, and the extractant extracts the reaction solution 3 times.

6. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The plasticizer is dibutyl phthalate, and the addition amount of the dibutyl phthalate is 10% of the mass of the alkali-soluble resin semi-finished product. The coupling agent is silane coupling agent KH-560, and the addition amount of the silane coupling agent KH-560 is 3% of the mass of the alkali-soluble resin semi-finished product. The stirring speed of mixing the alkali-soluble resin semi-finished product with the coupling agent and the plasticizer is 900 rpm, and the stirring time is 35 minutes.

7. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The reaction kettle is composed of a high-efficiency stirring mechanism, a precision thermometer, a condenser and a gas protection device.

8. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The volume of the deionized water is 4-6 times that of the reaction solution. The reaction solution is filtered in the deionized water by a vacuum filtration device. After the filtration is completed, the reaction solution is washed again with deionized water. The number of washing times with the deionized water is 2 times.

9. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The mass ratio of the epoxy compound to the reaction liquid is 1:5, the epoxy compound is one or more of dioxane, epichlorohydrin and bisphenol A epoxy resin, the catalyst is triethylamine, and the addition amount of the triethylamine is 3% of the total mass of the reaction liquid.

10. The method for preparing an alkali-soluble resin for PCB photoresist according to claim 1, characterized in that: The water content of the alkali-soluble resin after vacuum drying is less than 0.5% of the total mass of the alkali-soluble resin.

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