Film-forming resin for photoresist as well as preparation method and application of film-forming resin

Abstract

The invention relates to the technical field of film-forming resin, in particular to film-forming resin for photoresist and a preparation method and application thereof.The film-forming resin for the photoresist is prepared from, by weight, 18-40 parts of acrylate monomers, 5-15 parts of methacrylic acid, 3-10 parts of styrene analogues, 0.1-1 part of initiator and 40-60 parts of solvent. The provided film-forming resin has obviously improved mechanical strength, chemical stability and heat resistance, solves the problems of low hardness, poor chemical resistance, high coefficient of thermal expansion (CTE) and the like of the existing photosensitive solder resist dry film, and better meets the actual application requirements.

Description

Technical Field

[0001] This invention relates to the field of film-forming resin technology, specifically to a film-forming resin for photoresist, its preparation method, and its application. Background Technology

[0002] With the development of semiconductor components, electronic devices are becoming thinner, smaller, and more powerful. Semiconductor packaging is becoming miniaturized and multi-pin, with practical applications such as BGA (Ball Grid Array), CSP (Chip Scale Package), and FC (Flip Chip). This necessitates further thinning of permanent coatings such as solder resist layers. Common raw materials for preparing solder resist dry films include modified acrylic resins, acrylate monomers, photoinitiators, curing agents, fillers, colorants, and solvents. The selection and proportioning of different types of modified acrylic resins (such as modified acrylic resins containing photocurable functional groups, acid-modified resins, etc.) and other components will affect the performance of the dry film. Different application scenarios have different requirements for the performance of solder resist dry films, such as chemical resistance, yellowing resistance, high adhesion, low warpage, and flexibility. For example, some solder resist dry films need to have high reflectivity and high heat resistance, but may have poor chemical resistance; while others need to meet requirements such as good resistance to chemical nickel-palladium-gold alloys and good flatness. With the rapid development of the electronics industry, the performance requirements for photosensitive solder resist dry films are becoming increasingly stringent, such as higher resolution, lower coefficient of thermal expansion, better chemical resistance, better flexibility, and flame retardancy. This also places higher demands on the film-forming resin. Chinese patent application (publication number CN117487044 A) discloses film-forming resins and their preparation methods, as well as photoresists and their preparation methods. The main purpose is to balance low cost and high resolution, but properties such as mechanical strength and chemical stability need further improvement to meet the application requirements of solder resist dry films. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a film-forming resin for photoresists. By optimizing the selection and formulation of the resin monomers, the provided film-forming resin exhibits significantly improved mechanical strength, chemical stability, and heat resistance. This solves the problems of low hardness, poor chemical resistance, and high coefficient of thermal expansion (CTE) found in existing photosensitive solder resist dry films, thus better meeting the needs of practical applications.

[0004] The present invention provides a film-forming resin for photoresist, comprising, by weight, the following raw materials: 18-40 parts acrylate monomer, 5-15 parts methacrylic acid, 3-10 parts styrene analog, 0.1-1 parts initiator, and 40-60 parts solvent.

[0005] In one embodiment, the acrylate monomer is a combination of methyl methacrylate and butyl acrylate or ethyl acrylate.

[0006] In one embodiment, the mass ratio of methyl methacrylate to butyl acrylate or ethyl acrylate is 18-21:4-5.

[0007] In one embodiment, the styrene analogue includes one or more of styrene, naphthalenestyrene, naphthaleneethylene, stilbene, anthraceneethylene, or phenanthreneethylene.

[0008] In one embodiment, the initiator includes one or more of benzoyl peroxide, hydrogen peroxide of benzoic acid, tert-butylhydroperoxide, azobisisobutyronitrile, azodicyanocyclohexane, azobisisobutyramidine hydrochloride, or azobisisoheptanenitrile.

[0009] In one embodiment, the solvent includes one or more of toluene, acetone, butanone, dichloromethane, dichloroethane, trichloroethane, chloroform, dioxane, methyl ethyl ketone, methanol, water, diethyl ether, propylene glycol methyl ether, or ethylene glycol methyl ether.

[0010] In one embodiment, the solvent is a combination of acetone or butanone with propylene glycol methyl ether or ethylene glycol methyl ether.

[0011] In one embodiment, the mass ratio of acetone or butanone to propylene glycol methyl ether or ethylene glycol methyl ether is 1-2:1.

[0012] The film-forming resin provided by this invention, by employing methacrylic acid in combination with acrylate monomers, styrene analogs, and other raw materials, further controls the addition amount of each raw material in the system. This results in the product exhibiting optimal comprehensive performance in key indicators such as hardness, heat resistance, chemical resistance, and fine processability, with a good balance achieved among these properties. Specifically, when the acrylate monomers are a combination of methyl methacrylate and butyl acrylate or ethyl acrylate in a mass ratio of 18-21:4-5, the addition of styrene analogs ensures balanced inter-chain forces between the molecular chains of the film-forming resin, forming a dense cross-linked network. This not only improves hardness but also prevents cracking during development, while significantly enhancing solvent resistance.

[0013] Furthermore, this invention optimizes the solvent in the system by using a combination of acetone or butanone with propylene glycol methyl ether or ethylene glycol methyl ether, especially the combination of butanone and propylene glycol methyl ether, to promote monomer dissolution and chain transfer reaction control in the system, thereby improving molecular weight distribution and crosslinking uniformity.

[0014] Another aspect of the present invention provides a method for preparing a film-forming resin for photoresist, comprising the following steps: adding 30-45 parts by weight of solvent to a container, and under stirring conditions, controlling the temperature at 70-75°C, adding dropwise a mixture containing 18-40 parts of acrylate monomer, 5-15 parts of methacrylic acid, 3-10 parts of styrene analog, 0.05-0.7 parts of initiator, and 5-8 parts of solvent, adding dropwise for 3-4 hours, and maintaining the temperature for 1-2 hours; adding dropwise the remaining mixture of initiator and solvent, adding dropwise for 0.25-0.5 hours, and raising the temperature to 85-90°C and maintaining the temperature for 5-6 hours.

[0015] A third aspect of the present invention provides a solder resist dry film, wherein the raw materials for preparing the solder resist dry film include: 20-40 parts film-forming resin, 20-30 parts photocurable resin, 20-35 parts thermocurable resin, 1-3 parts photoinitiator, 1-5 parts pigment, 0.01-0.05 parts defoamer, 20-35 parts inorganic filler, 2-8 parts diluent, and 0.2-1 parts polymerization inhibitor.

[0016] In one embodiment, the raw materials for preparing the solder resist dry film include: 25-30 parts film-forming resin, 20-25 parts photocurable resin, 25-28 parts thermocurable resin, 1.5-2 parts photoinitiator, 2-3 parts pigment, 0.01-0.02 parts defoamer, 25-28 parts inorganic filler, 4-5 parts diluent, and 0.3-0.5 parts polymerization inhibitor.

[0017] In one embodiment, the photocurable resin includes a phenolic epoxy acrylate resin, specifically model XY641, sourced from Anhui Xinyuan Technology Co., Ltd.

[0018] In one embodiment, the thermosetting resin includes bisphenol A epoxy resin, the type of which is BE188EL, and it is sourced from Chang Chun Chemical Co., Ltd. in Taiwan, China.

[0019] In one embodiment, the diluent comprises DPHA (dipentaerythritol hexaacrylate).

[0020] In one embodiment, the photoinitiator is designated Irgacure 369.

[0021] In one embodiment, the inorganic filler comprises barium sulfate.

[0022] In one embodiment, the pigment includes phthalocyanine green.

[0023] In one embodiment, the polymerization inhibitor comprises p-methoxyphenol.

[0024] In one embodiment, the defoamer is designated BYK-A 500.

[0025] The solder resist dry film provided by this invention, by using film-forming resin in combination with other raw materials, enables the product to meet many performance requirements such as high resolution, high hardness, and good chemical resistance, while greatly reducing exposure time and exposure energy. This allows it to achieve a relatively high exposure level at a lower energy, greatly improving production efficiency and facilitating large-scale industrial production.

[0026] Beneficial effects 1. This invention provides a film-forming resin for photoresist. By optimizing the selection and formulation of the film-forming resin monomers, the provided film-forming resin has significantly improved mechanical strength, chemical stability and heat resistance, solving the problems of low hardness, poor chemical resistance and high coefficient of thermal expansion (CTE) of existing photosensitive solder resist dry films, and better meeting the needs of practical applications.

[0027] 2. The film-forming resin provided by the present invention, by using methacrylic acid in combination with acrylate monomers and styrene analogs and other raw materials, further controls the amount of each raw material added in the system, so that the provided product exhibits the best comprehensive performance in key indicators such as hardness, heat resistance, chemical resistance and fine processability, and achieves a good balance among various properties.

[0028] 3. Especially when the acrylate monomers are a combination of methyl methacrylate and butyl acrylate or ethyl acrylate in a mass ratio of 18-21:4-5, the addition of styrene analogs ensures the balance of forces between the molecular chain segments of the film-forming resin, forming a dense cross-linked network, which not only improves hardness but also avoids cracking during development, while significantly enhancing solvent resistance.

[0029] 4. This invention optimizes the solvent in the system by using a combination of acetone or butanone and propylene glycol methyl ether or ethylene glycol methyl ether, especially the combination of butanone and propylene glycol methyl ether, to promote monomer dissolution and chain transfer reaction control in the system, and improve molecular weight distribution and crosslinking uniformity.

[0030] 5. The solder resist dry film provided by the present invention, by using film-forming resin in combination with other raw materials, enables the product to meet many performance requirements such as high resolution, high hardness, and good chemical resistance, while greatly reducing exposure time and exposure energy. This allows it to achieve a relatively high exposure level at a lower energy, greatly improving production efficiency and making it easy to realize large-scale industrial production. Detailed Implementation

[0031] Examples 1-8 Examples 1-8 of the present invention provide a film-forming resin for photoresist, the formulation of which is shown in Table 1 by weight.

[0032] Table 1

[0033] In another aspect, Examples 1-8 of the present invention provide a method for preparing a film-forming resin for photoresist, comprising the following steps: adding 41 parts by weight of solvent to a container, controlling the temperature at 75°C under stirring conditions, and dropwise adding a mixture containing acrylate monomer (Table 1 dosage), methacrylic acid or acrylic acid (Table 1 dosage), styrene analog (Table 1 dosage), 0.03 parts of initiator, and 7 parts of solvent, dropwise for 3 hours, and maintaining the temperature for 1 hour; dropwise adding the remaining mixture of initiator and solvent, dropwise for 0.5 hours, and raising the temperature to 90°C and maintaining the temperature for 6 hours.

[0034] Application Examples 1-8 Application Examples 1-8 of the present invention provide a solder resist dry film, the formulation of which is shown in Table 2 by weight.

[0035] Table 2

[0036] The preparation method of the solder resist dry film is as follows: stir and mix the raw materials in Table 2 to obtain a coating composition, dilute the coating composition with acetone (the mass ratio of coating composition to acetone is 20:1), coat it on the surface of the carrier film (PET film), and bake it at 110°C for 10 minutes to obtain the solder resist dry film.

[0037] Performance testing 1. Pencil hardness test (surface rigidity characterization): Referring to standard ASTM D3363, the solder resist dry film provided in the application example was cured for 24 hours at 23±2℃ and 50±5%RH. Mitsubishi pencils (6B-9H) with increasing hardness were used to advance 6.5mm at a 45° angle. According to the judgment criteria (pass: no scratches or only slight surface marks (<10% of film thickness); fail: obvious scratches or plastic deformation), the highest passing hardness grade of the 3 tests was taken. The results are shown in Table 3.

[0038] Table 3

[0039] Analysis of the data in Table 3 shows that the solder resist dry film pencil made from the film-forming resin synthesized in this invention has a high hardness, with Application Example 1 showing the best effect in terms of hardness improvement.

[0040] 2. Glass transition point (TG) test: Referring to standard ASTM D7028, the solder resist dry film provided in the application example was cured at 23±2℃ and 50±5%RH for 24 hours. After sampling, the TG was tested by differential scanning calorimetry (DSC). According to the judgment criteria (the measured TG value is considered passing if it is greater than 140℃, and failing if it is lower than 140℃), the average TG value during each heating process was taken as the result. The results are shown in Table 4. Table 4

[0041] Analysis of the data in Table 4 shows that the solder resist dry film made from the film-forming resin synthesized in this invention has a high TG (heat resistance). Among them, Application Example 1 shows the best effect in terms of TG improvement. This proves that the film-forming resin provided by this invention can effectively improve heat resistance, enhance the rigidity and dimensional stability of the material.

[0042] 3. Solvent resistance to wiping (MEK double wiping test): Refer to ASTM D5402 and conduct the test according to the following experimental procedure. The test results are shown in Table 5.

[0043] Experimental procedure: Wrap two layers of cotton gauze (5×5cm) around the bottom of a 500g weight; The solder resist dry film provided in the application example is impregnated with methyl ethyl ketone (MEK), and wiped once per second (one-way distance is 10cm). Replace the gauze every 50 times and record the number of times the film layer is exposed. The same sample was measured in three regions, and the average value was taken.

[0044] Table 5

[0045] Analysis of the data in Table 5 shows that the solder resist dry film made from the film-forming resin synthesized in this invention has high solvent wiping resistance. Among them, Application Example 1 has the best effect in terms of TG improvement. The number of MEK wipes of the solder resist dry film made from the film-forming resin of this invention is better than that of commercially available solder resist dry films, which proves that the film-forming resin of this invention can effectively form a denser and more stable three-dimensional cross-linked network, which greatly improves the solvent resistance and mechanical strength of the coating.

[0046] 4. Comparison Test of Resolution and Adhesion Performance 4.1 Exposure Test: The dry film was exposed using a 365nm UV-LED light source (intensity 30mW / cm²) through a resolution test substrate (containing 5-150μm linewidth patterns), with exposure energy gradients set to 600, 800, 1000, 1200, and 1400mJ / cm².

[0047] 4.2 Development: Develop by spraying with a 1wt% sodium carbonate aqueous solution (30℃, 0.2MPa pressure), then wash and dry.

[0048] 4.3 Resolution Evaluation: The resolution and adhesion of the dry film were observed using a metallographic microscope, and the results were then compared. See Table 6.

[0049] Table 6

[0050] Analysis of the data in Table 6 shows that the solder resist dry film made by the film-forming resin of the present invention has excellent resolution and adhesion, proving that the film-forming resin of the present invention can effectively improve the performance of the dry film and meet the needs of precision circuit manufacturing. It also shows that the film-forming resin in the present invention has good chemical resistance and high reliability.

Claims

1. A film-forming resin for photoresist, characterized in that, By weight parts, including the following raw materials: 18-40 parts of acrylate monomer, 5-15 parts of methacrylic acid, 3-10 parts of styrene analog, 0.1-1 parts of initiator, 40-60 parts of solvent.

2. The film forming resin according to claim 1, characterized by The acrylate monomer is a combination of methyl methacrylate and butyl acrylate or ethyl acrylate.

3. The film forming resin according to claim 2, characterized in that, The mass ratio of the methyl methacrylate and butyl acrylate or ethyl acrylate is 18-21:4-5.

4. The film forming resin according to claim 1, characterized by The styrene analog includes one or more of styrene, naphthalene styrene, naphthalene vinyl, diphenyl ethylene, anthracene ethylene or phenanthrene ethylene.

5. The film forming resin according to claim 1, wherein The initiator includes one or more of benzoyl peroxide, peroxide benzoic acid, tert-butoxy peroxide hydrogen peroxide, azobis diisobutyronitrile, azobis dicyanocyclohexane, azobis diisobutyramide hydrochloride or azobis diisobutyronitrile.

6. The film forming resin according to claim 1, wherein The solvent includes one or more of toluene, acetone, butanone, dichloromethane, dichloroethane, trichloroethane, chloroform, dioxane, methyl ethyl ketone, methanol, water, diethyl ether, propylene glycol methyl ether or ethylene glycol methyl ether.

7. The film forming resin according to claim 6, characterized in that, The solvent is a combination of acetone or butanone and propylene glycol methyl ether or ethylene glycol methyl ether.

8. A process for the preparation of a film-forming resin according to any one of claims 1 to 7, characterized in that, Including the following steps: 30-45 parts by weight of solvent are added to a container, and under stirring, the temperature is controlled at 70-75℃, and a mixture containing 18-40 parts of acrylate monomer, 5-15 parts of methacrylic acid, 3-10 parts of styrene analog, 0.05-0.7 parts of initiator, 5-8 parts of solvent is added dropwise, dropwise for 3-4h, and incubated for 1-2h; The mixture of the remaining amount of initiator and solvent is added dropwise for 0.25-0.5h, and the temperature is raised to 85-90℃ for 5-6h.

9. A solder resist dry film characterized by, The film-forming resin according to any one of claims 1-7.

10. The solder resist dry film according to claim 9, wherein The preparation raw materials of the solder resist dry film include: 20-40 parts of film-forming resin, 20-30 parts of photocuring resin, 20-35 parts of thermocuring resin, 1-3 parts of photoinitiator, 1-5 parts of pigment, 0.01-0.05 parts of defoaming agent, 20-35 parts of inorganic filler, 2-8 parts of diluent, 0.2-1 parts of polymerization inhibitor.

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