A photosensitive resin composition and a dry film resist laminate

Abstract

The present invention relates to a photosensitive resin composition and a dry film resist laminate thereof, belonging to the technical field of printed circuit boards. A photosensitive resin composition includes an alkali-soluble resin, a photopolymerizable monomer, and a photoinitiator. The alkali-soluble resin at least includes a segment formed by a vinyl carbonate I monomer, and the vinyl carbonate I is a vinyl carbonate with a benzene ring. The present invention uses vinyl carbonate I containing a benzene ring structure to prepare the photosensitive resin composition. In addition to having excellent resolution and adhesion, since the segment formed by the vinyl carbonate I monomer will decompose to form a structure with hydroxyl groups and CO2, it can interact with the stripping solution during the stripping process, which is beneficial to the peeling of the cured resist pattern. At the same time, the released gas will accelerate the stripping process, making it have a faster stripping speed, thereby improving the production efficiency.

Description

Technical Field

[0001] The present invention relates to a photosensitive resin composition and a dry film resist laminate thereof, belonging to the technical field of printed circuit boards. Background Art

[0002] Against the backdrop of the large-scale popularization of intelligent terminal devices and the rapid advancement of 5G construction, new changes are taking place in the technology of the printed circuit board (PCB) industry. For PCB products, high density, flexibility, and high integration are the future development directions. When manufacturing printed circuit boards, a photosensitive resin composition used as a resist material for pattern transfer in etching or electroplating and a dry film resist layer containing the photosensitive resin composition between a support film and a protective film are widely used. Generally, the dry film resist layer is laminated on a copper substrate, and after exposure, the unexposed part in the dry film resist layer is dissolved or dispersed and removed by a developer, and then subjected to etching or electroplating treatment to form a pattern. Finally, the cured resist pattern is peeled off by a stripping solution.

[0003] For the production of high-density and high-integration PCB products such as HDI boards and IC substrates, a precision of about 15 μm is generally required. This requires the dry film resist layer for pattern transfer to have higher resolution and excellent adhesion on the copper substrate to ensure that the dry film remains intactly attached to the copper clad laminate substrate after harsh processes such as high-pressure spraying, long-term contact with corrosive chemical reagents in development, electroplating, or etching.

[0004] In the dry film resist layer, the two most important properties are resolution and adhesion. Generally, in the prior art, methods such as reducing the film thickness of the dry film resist layer, reducing the molecular weight of the alkali-soluble resin, increasing the content of benzene ring-containing monomers in the alkali-soluble resin, and selecting polyfunctional photopolymerizable monomers can improve resolution and adhesion.

[0005] However, these methods will simultaneously affect the properties of the dry film resist layer such as masking hole performance, flexibility, and plating resistance, affecting the production of downstream clients and causing losses to the company.

[0006] It can be seen that for the properties of the dry film resist, it is necessary to balance high resolution, good adhesion on the copper substrate, good flexibility, and etching resistance.

[0007] Patent documents CN101568883B and CN109324480A improve the hydrophobic property of the photosensitive resist layer by increasing the content of (meth)acrylic acid benzyl ester derivatives and styrene derivatives in the alkali-soluble resin, thereby obtaining a dry film resist with good resolution and adhesion. CN102385253B uses an adhesive polymer with a specific structure, namely, a structure of (meth)acrylic acid benzyl ester and styrene in the polymer, to obtain a photosensitive resin composition with excellent resolution and stripping characteristics. Patent CN110531583A adds a (meth)acrylic acid hydroxyethyl ester structure to the alkali-soluble resin, significantly enhancing the resistance to acid etching solution and electroplating solution and the stripping performance; CN110632825A prepares an alkali-soluble resin with good flexibility and low monomer residue rate by connecting a carbon atom between the acyloxy group and the benzene ring in (meth)acrylic acid benzyl ester, which has excellent adhesion, resolution, and flexibility when used as a dry film resist.

[0008] By analyzing existing patents, generally good resolution and adhesion can be obtained, but there are still deficiencies in the development speed, stripping speed, and stripping fragments. Summary of the Invention

[0009] The present invention aims to solve the above problems and thus provides a photosensitive resin composition. In the photosensitive resin composition of the present invention, the alkali-soluble resin component contains a vinyl carbonate structure, so that the photosensitive resin composition not only has excellent resolution and adhesion, but also has a fast development speed and stripping speed, and the size of the stripping fragments is small, and the size is moderate and conducive to removal, effectively improving the product yield and production efficiency.

[0010] The technical solution for the present invention to solve the above problems is as follows:

[0011] A photosensitive resin composition, comprising an alkali-soluble resin, a photopolymerizable monomer, and a photoinitiator, wherein the alkali-soluble resin contains a segment formed by vinyl carbonate I monomer, and the vinyl carbonate I monomer is a vinyl carbonate with a benzene ring, and the structural formula is as follows:

[0012]

[0013] Where n is 0 to 12.

[0014] As a preference of the above technical solution, the vinyl carbonate I is selected from one or more of phenyl vinyl carbonate, benzyl vinyl carbonate, ethylphenyl vinyl carbonate, butylphenyl vinyl carbonate, undecylphenyl vinyl carbonate.

[0015] Preferably, as the above technical solution, the alkali-soluble resin further contains a chain segment formed by one or more of (meth)acrylic acid, (meth)acrylic acid alkyl ester, and (meth)styrene monomers.

[0016] Preferably, as the above technical solution, the (meth)acrylic acid alkyl ester is selected from one or more of (meth)acrylic acid alkyl esters having 1 to 12 carbon atoms; the (meth)styrene is selected from one or two of styrene and α-methylstyrene.

[0017] In the above technical solution of the present invention, C1-C12 refers to the number of central carbon atoms of the main chain alkyl ester.

[0018] Preferably, as the above technical solution, the alkali-soluble resin contains a chain segment formed by monomers in the following parts by mass:

[0019]

[0020] The weight-average molecular weight is 20,000 to 80,000, the acid value is 130 to 228 mgKOH / g, and the polydispersity index is 1 to 3.

[0021] In the above technical solution of the present invention, the polydispersity index is the weight-average molecular weight / number-average molecular weight.

[0022] In the above technical solution of the present invention, considering the developability and solvent resistance, an alkali-soluble resin with a weight-average molecular weight of 30,000 to 60,000 and an acid value of 130 to 190 mgKOH / g is further preferred.

[0023] Preferably, as the above technical solution, the polydispersity index of the alkali-soluble resin is 1.1 to 2.5.

[0024] In the above technical solution of the present invention, considering the resolution and adhesion, an alkali-soluble resin with a polydispersity index of 1.1 to 2.5 is further preferred.

[0025] The alkali-soluble resin further includes a chain segment formed by vinyl ester II and / or vinyl carbamate III monomers. The structural formula of vinyl ester II is as follows:

[0026]

[0027] Among them, R1 represents a carbon chain having a carbocyclic ring with 6 to 20 carbon atoms. The carbocyclic ring is saturated or unsaturated, and the carbon chain is saturated;

[0028] The structural formula of vinyl carbamate III is as follows:

[0029]

[0030] Among them, R2 represents hydrogen or methyl; R3 represents a carbocyclic carbon chain having 6 to 20 carbon atoms, the carbocyclic ring being saturated or unsaturated, and the carbon chain being saturated.

[0031] As a preference of the above technical solution, the photosensitive resin composition includes 45 to 65 parts by mass of the alkali-soluble resin, 30 to 50 parts by mass of the photopolymerizable monomer, and 0.1 to 10 parts by mass of the photoinitiator.

[0032] In the above technical solution of the present invention, considering film-forming property, photosensitivity, and resolution, the mass parts of the alkali-soluble resin are controlled at 45 to 65 parts. When it is less than 45 parts, the film-forming property is poor and the glue is likely to overflow during winding; when it is more than 65 parts, the photosensitivity is poor and the resolution is low.

[0033] In the above technical solution of the present invention, considering film-forming property, photosensitivity, and resolution, the mass parts of the photopolymerizable monomer are controlled at 30 to 50 parts. When it is less than 30 parts, there may be poor photosensitivity and low resolution; when it is more than 50 parts, the film-forming property is poor, and problems such as glue overflow and short storage life will occur.

[0034] In the above technical solution of the present invention, considering photosensitivity and resolution, the photoinitiator is controlled at 0.1 to 10 parts by mass. When the mass parts of the photoinitiator are within 0.1 to 10, it has better photosensitivity and resolution.

[0035] As a preference of the above technical solution, the photopolymerizable monomer is selected from one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, trimethylolpropane tri(meth)acrylate, ethoxylated (propoxylated) trimethylolpropane tri(meth)acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, hexanediol diacrylate, bisphenol A di(meth)acrylate, ethoxylated (propoxylated) bisphenol A di(meth)acrylate, polyethylene glycol (propylene glycol) di(meth)acrylate, ethoxylated (propoxylated) neopentyl glycol diacrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, nonylphenol acrylate, ethoxylated (propoxylated) nonylphenol acrylate, isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate.

[0036] As a preference of the above technical solution, the photoinitiator is selected from one or more of 2,4,5-triaryl imidazole dimer or its derivatives, N,N'-tetramethyl-4,4'-diaminobenzophenone, 9-phenylacridine, N-phenylglycine, coumarin-based compounds, thioxanthone-based compounds, anthraquinone or its derivatives.

[0037] Preferably, as the above technical solution, it further includes 0.5 to 5 parts by mass of an additive assistant, and the additive assistant includes dyes, color formers, color developing heat stabilizers, plasticizers, defoamers, fillers, adhesion promoters, leveling agents, peeling promoters, antioxidants, and thermal crosslinking agents.

[0038] Preferably, as the above technical solution, the dye is malachite green, the color former is leuco crystal violet, and the plasticizer is p-toluenesulfonamide.

[0039] Another object of the present invention is to provide a dry film resist laminate.

[0040] A dry film resist laminate includes a support layer and a photosensitive layer, and the photosensitive layer is formed from the above photosensitive resin composition.

[0041] In the above technical solution of the present invention, the support layer includes PET, PE, etc.

[0042] In summary, the present invention has the following beneficial effects:

[0043] 1. The present invention uses vinyl carbonate I containing a benzene ring structure to formulate a photosensitive resin composition. In addition to having excellent resolution and adhesion, since the vinyl carbonate chain segment will decompose to form a structure with hydroxyl groups and CO2, it can interact with the stripping solution during the stripping process, which is beneficial to the peeling of the cured resist pattern. At the same time, the released gas will accelerate the stripping process, making it have a faster stripping speed, thereby improving production efficiency;

[0044] 2. The present invention selects vinyl carbonate monomer I as the monomer for synthesizing the alkali-soluble resin. In addition to having excellent resolution and adhesion, the test shows that the development speed is fast, the stripping speed is fast, and the size of the stripping fragments is moderate, which is beneficial to removal, and can effectively improve the product yield and production efficiency;

[0045] 3. Vinyl carbonate I, vinyl ester II, and vinyl carbamate III used in the resin have lower biological toxicity compared to (meth)acrylate monomers, and are more excellent monomer choices. Adding vinyl ester II on the basis of vinyl carbonate I can increase flexibility, and adding vinyl carbamate III can increase toughness and adhesion. Detailed Embodiments

[0046] In order to further illustrate the technical effects of the present invention, the embodiments of the present invention will be described in detail below.

[0047] This specific embodiment is only an interpretation of the present invention and does not limit the present invention. Any changes made by those skilled in the art after reading this specification will be protected by the patent law as long as they are within the scope of the claims.

[0048] 1. Alkaline-soluble resin A: Prepared by solution polymerization, with acetone as the solvent

[0049]

[0050]

[0051] 2. Photopolymerizable monomer B

[0052] B1: (8) Ethoxylated nonylphenol acrylate;

[0053] B2: (10) Ethoxylated bisphenol A diacrylate;

[0054] B3: (3) Ethoxylated trimethylolpropane triacrylate;

[0055] B4: Polyethylene glycol (400) dimethacrylate;

[0056] 3. Photoinitiator C

[0057] C1: 2,2’,4-Tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4’,5’-diphenyl-1,1’-diimidazole;

[0058] C2: N-Phenylglycine;

[0059] 4. Additive D

[0060] D1: Malachite green;

[0061] D2: Leuco crystal violet;

[0062] D3: Tribromomethylphenyl sulfone;

[0063] D4: p-Toluenesulfonamide;

[0064] According to the following parts by weight of each component of the dry film resist, mix in proportion, add a certain amount of methyl ethyl ketone or acetone, and then stir well until completely dissolved to prepare an anti-corrosion solution with a solid content of 42%. Use a coater to evenly coat it on the surface of a 15-μm-thick PET support film, place it in an oven at 90 °C for 8 minutes to form a 25-μm-thick dry film resist layer, which appears blue-green under a yellow light. Then, attach a 18-μm-thick polyethylene film protective layer to its surface to obtain a three-layer structured photosensitive dry film.

[0065] 5. Parts by weight of the dry film resist

[0066]

[0067] The following describes the sample preparation methods (including film lamination, exposure, development, and film stripping), sample evaluation methods, and evaluation results of the examples and comparative examples.

[0068]

Film Laminating

[0069] The copper clad laminate is polished on its copper surface by a grinding machine, washed with water, and dried to obtain a bright and fresh copper surface. Set the temperature of the pressure roller of the film laminating machine to 110°C, the conveying speed to 1.5 m / min, and perform thermal lamination under standard pressure.

[0070]

Exposure

[0071] After film lamination, the sample is left standing for more than 15 minutes. Use Orbotech exposure machine, model: Paragon - 8000M, a laser direct imaging (LDI) exposure machine with a wavelength of 355 nm for exposure. Use a stouffer 41 - step exposure scale for photosensitivity testing. The exposure grid count is controlled within 14 - 20 grids, and the exposure energy is 8 - 20 mJ / cm 2 。

[0072]

Development

[0073] After exposure, the sample is left standing for more than 15 minutes. The development temperature is 30°C, the pressure is 1.2 Kg / cm 2 , the developer is a 1% wt aqueous sodium carbonate solution, the development time is 1.5 - 2.0 times the minimum development time, and after development, it is washed with water and dried.

[0074]

Film Stripping

[0075] The film stripping solution is NaOH, with a concentration of 3.0 wt%, a temperature of 50°C, and a development pressure of 1.2 Kg / cm 2 , the film stripping time is 1.5 - 2.0 times the minimum film stripping time, and after film stripping, it is washed with water and dried.

[0076]

Evaluation of Resolution

[0077] Use a mask with a wiring pattern having widths of the exposed part and the unexposed part of n:n (n is 10 - 100 μm) for exposure. After developing with 1.5 times the minimum development time, take the minimum mask width at which the cured resist lines are normally formed as the resolution value and observe it with a magnifying glass.

[0078]

Evaluation of Adhesion

[0079] Stack a photosensitive dry film resist on the copper plate by thermal lamination. Use a mask with a wiring pattern having widths of the exposed part and the unexposed part of n:400 (n is 10 - 100 μm) for exposure. After developing with 1.5 times the minimum development time, take the minimum mask width at which the cured resist lines are normally formed as the adhesion value and observe it with a magnifying glass.

[0080]

Minimum Development Time

[0081] After applying the film, let it stand for more than 15 min, the developing temperature is 30 °C, and the pressure is 1.2 Kg / cm 2 . The developing solution is a 1% wt aqueous sodium carbonate solution, and the minimum time required to completely dissolve the unexposed part of the resist layer is taken as the minimum developing time.

[0082]

Evaluation of stripping speed

[0083] Take 1 substrate after film application, exposure, and development, cut it into a 4*5 cm square, put it into a beaker containing 100 mL of stripping solution (concentration 3 wt%, temperature 50 °C), and after magnetic stirring for 1 min, record the time when the dry film completely falls off. The stripping speed is evaluated by measuring the stripping time. The shorter the stripping time, the faster the stripping speed.

[0084]

Evaluation of stripping fragment size

[0085] Take 1 substrate after film application, exposure, and development, cut it into a 4*5 cm square, put it into a beaker containing 100 mL of stripping solution (concentration 3 wt%, temperature 50 °C), and after magnetic stirring for 1 min, observe the size of the stripping fragments. Good: The fragment size is 5 - 15 mm; General: The fragment size is 20 - 30 mm; Poor: The fragment size is more than 30 mm or less than 5 mm.

[0086]

[0087] By comparing Examples 1 - 12 with Comparative Examples 1 - 2, it can be found that: in Examples 1 - 12, photosensitive resin compositions with excellent resolution and adhesion, and fast developing and stripping speeds were obtained; in terms of the stripping fragment size, the stripping fragment sizes of Examples 1 - 5, 7 - 9, and 12 were good, and those of Examples 6 and 10 - 11 were general; while Comparative Example 1 showed poor performance in terms of development, stripping, and stripping fragments, and Comparative Example 2 was general. Thus, it can be seen that the present invention selects vinyl carbonate monomer I as the monomer for synthesizing the alkali-soluble resin, making the obtained photosensitive resin composition have excellent resolution and adhesion, and showing better performance in development and stripping.

Claims

1. A photosensitive resin composition, characterized in that: It includes an alkali-soluble resin, a photopolymerizable monomer and a photoinitiator. The alkali-soluble resin contains a segment formed from a vinyl carbonate I monomer, and the vinyl carbonate I monomer is a vinyl carbonate with a benzene ring, and the structural formula is as follows: Where n is from 0 to 12.

2. The photosensitive resin composition according to claim 1, wherein: The vinyl carbonate I is selected from one or more of phenyl vinyl carbonate, benzyl vinyl carbonate, ethylphenyl vinyl carbonate, butylphenyl vinyl carbonate, undecylphenyl vinyl carbonate.

3. The photosensitive resin composition according to claim 1, wherein: The alkali-soluble resin further contains a segment formed from one or more of (meth)acrylic acid, (meth)acrylic acid alkyl ester, (meth)styrene monomers.

4. A photosensitive resin composition according to claim 3, characterized in that: The (meth)acrylic acid alkyl ester is selected from one or more of (meth)acrylic acid alkyl esters with C1-C12; the (meth)styrene is selected from one or two of styrene and α-methylstyrene.

5. The photosensitive resin composition according to claim 3, wherein: The alkali-soluble resin contains a segment formed from the following mass parts of monomers: The weight average molecular weight is from 20,000 to 80,000, the acid value is from 130 to 228 mgKOH / g, and the polydispersity index is 1-3.

6. The photosensitive resin composition according to claim 1, characterized in that: The alkali-soluble resin further includes a segment formed from a vinyl ester II and / or a vinyl carbamate III monomer, and the structural formula of the vinyl ester II is as follows: Wherein, R1 represents a carbon chain with a carbocyclic ring having 6 to 20 carbon atoms, the carbocyclic ring is saturated or unsaturated, and the carbon chain is saturated; The structural formula of the vinyl carbamate III is as follows: Wherein, R3 represents a carbon chain with a carbocyclic ring having 6 to 20 carbon atoms, the carbocyclic ring is saturated or unsaturated, and the carbon chain is saturated; R2 represents hydrogen or methyl.

7. A photosensitive resin composition according to claim 1, characterized in that: The photosensitive resin composition includes 45 to 65 parts by weight of an alkali-soluble resin, 30 to 50 parts by weight of a photopolymerizable monomer, and 0.1 to 10 parts by weight of a photoinitiator.

8. A photosensitive resin composition according to claim 1, characterized in that: The photopolymerizable monomer is selected from one or several of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, trimethylolpropane tri(meth)acrylate, ethoxylated (propoxylated) trimethylolpropane tri(meth)acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, hexanediol diacrylate, bisphenol A di(meth)acrylate, ethoxylated (propoxylated) bisphenol A di(meth)acrylate, polyethylene glycol (propylene glycol) di(meth)acrylate, ethoxylated (propoxylated) neopentyl glycol diacrylate, (meth)acrylic acid isooctyl ester, (meth)acrylic acid lauryl ester, nonylphenol acrylate, ethoxylated (propoxylated) nonylphenol acrylate, (meth)acrylic acid isobornyl ester, (meth)acrylic acid tetrahydrofuran ester.

9. The photosensitive resin composition according to claim 1, wherein: The photoinitiator is selected from one or several of 2,4,5-triaryl imidazole dimers or their derivatives, N,N'-tetramethyl-4,4'-diaminobenzophenone, 9-phenyl acridine, N-phenylglycine, coumarin compounds, thioxanthone compounds, anthraquinone or its derivatives.

10. A dry film resist laminate, comprising a support layer and a photosensitive layer, characterized in that: The photosensitive layer is formed of the photosensitive resin composition according to any one of claims 1 to 9, and the support layer is one or more of a PET layer and a PP layer.

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