Photosensitive dry film resist and preparation method and application thereof

Abstract

The invention provides a photosensitive dry film resist and a preparation method and application thereof, and the photosensitive dry film resist comprises the following components in percentage by weight: 40-60% of alkali-soluble polyacrylic resin; 30%-50% of a photopolymerization monomer; 1%-5% of a photopolymerization initiator; 5%-15% of an additive; the alkali-soluble polyacrylic resin is obtained through reaction of a first monomer, a second monomer and a third monomer. The photosensitive dry film resist provided by the invention has excellent adhesive force, high resolution and electroplating resistance, has a phenolic hydroxyl structure, is good in water solubility, and is beneficial to acceleration of development and film stripping speed and improvement of production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of photosensitive materials technology, and relates to a photosensitive dry film resist, its preparation method and application, specifically a photosensitive dry film resist with high adhesion, high resolution, anti-electroplating, and rapid development, its preparation method and application. Background Technology

[0002] Photosensitive dry film photoresists are widely used in printed circuit boards (PCBs), semiconductor packaging (ICs), and lead frames. Leveraging the significant difference in their physicochemical properties before and after exposure, they completely transfer pre-set, precise patterns onto the corresponding substrate. PCBs are a core component of the electronics and information technology industry. With the rise and explosive growth of the artificial intelligence (AI) industry in the past two years, a new wave of AI product innovation and application demands has emerged in areas such as smartphones, personal computers (PCs), and intelligent vehicles. Correspondingly, PCBs require significant upgrades in materials and structural design. AI electronic products demand higher circuit density on PCBs, meaning more integrated circuits within the same area. Therefore, extremely stringent requirements are placed on the photosensitive dry film materials used to manufacture these high-end PCB circuits in terms of adhesion, resolution, and electroplating resistance.

[0003] To improve the adhesion, resolution, and electroplating resistance of photosensitive dry film resists, a common practice is to introduce comonomers with benzyl ring structures, such as benzyl (meth)acrylate and its derivatives, and styrene and its derivatives, into alkali-soluble polyacrylic acid resins. This aims to utilize the conjugation effect of benzyl rings with copper atoms to enhance the adhesion strength between the resist layer and the copper substrate, as well as improve the electroplating solution's resistance to electroplating. Simultaneously, the rigid structure of the benzyl ring itself is used to improve the resolution of the resist lines. Typically, the benzyl ring and its derivative structures introduced into the alkali-soluble resin constitute a relatively large proportion, generally between 5% and 30%, to achieve a certain degree of improvement in the adhesion and resolution of the dry film resist, but still not reaching the target product quality of high yield. However, the high benzyl ring content in the resin structure results in a higher glass transition temperature, reducing the flexibility of the formulated dry film resist layer, leading to insufficient adhesion and bonding with the copper-clad laminate substrate, causing plating problems in the electroplating solution. This cannot meet the demands of increasingly high-end and fine-grained circuit board manufacturing.

[0004] Researchers have discovered that marine mussels can firmly adhere to marine rocks because they secrete a 3,4-dihydroxyphenyl-L-alanine containing a catechol (also known as catechin) group. Catechol is key to the tight interfacial bonding of adhesive proteins. The catechol group can form complex coordination with metal ions, forming monodentate, bidentate, and tripentate complex coordination depending on the ion type and pH value. It can also form hydrogen bonds and π-π non-covalent bonds. Utilizing this property of catechol, it (such as its dopamine structure) has been incorporated into the side chains of polymer systems, leading to the development of various biomimetic adhesives.

[0005] Therefore, by introducing a polyhydroxystyrene derivative structure similar to the catechol group into alkali-soluble polyacrylic acid resin, even a small proportion can significantly improve the adhesion between the dry film resist and the copper surface through the metal coordination between its bis / polyphenolic hydroxyl groups and the copper substrate. This avoids the resist layer becoming hard and brittle due to an excessive number of benzene ring structural groups, thus simultaneously ensuring high resolution, high electroplating resistance, and high toughness. Furthermore, since the polyphenolic hydroxyl group (such as catechol) structure can form hydrogen bonds well with water, it helps to shorten the development time of the resist layer during the development process, accelerating production efficiency. However, most of the currently developed biomimetic polymers containing catechol introduce dopamine structures as comonomers, which are relatively expensive and cannot be used for large-scale industrial production.

[0006] Therefore, in order to improve the production efficiency and yield of high-end PCB boards, it is urgent for the industry to develop a type of alkali-soluble polyacrylic acid resin with readily available monomer raw materials. When applied to photosensitive dry film resist, it can simultaneously possess high resolution, electroplating resistance, fast development speed, and excellent adhesion performance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a photosensitive dry film resist, its preparation method, and its application. Specifically, it provides a photosensitive dry film resist with high adhesion, high resolution, electroplating resistance, and rapid development, along with its preparation method and application. This invention provides a novel alkali-soluble polyacrylic acid resin with a polyphenolic hydroxyl styrene derivative monomer unit structure. The photosensitive dry film resist prepared using the alkali-soluble polyacrylic acid resin of this invention exhibits excellent adhesion to copper-clad laminates, and also possesses excellent high resolution, resistance to electroplating and etching, and rapid development efficiency.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a photosensitive dry film resist (which is a photosensitive resin composition), said photosensitive dry film resist comprising, by weight percentage, the following components: Alkali-soluble polyacrylic acid resin 40%~60%; Photopolymerizable monomers 30%~50%; Photopolymerization initiator 1%~5%; Additives 5%~15%; The alkali-soluble polyacrylic acid resin is obtained by reacting a first monomer, a second monomer, and a third monomer. The first monomer has the structure shown in Formula I: Formula I; In Formula I, R1 is a hydrogen atom or a methyl group; The second monomer has the structure shown in Formula II: Formula II; In Formula II, R2 is a hydrogen atom or a methyl group, and R3, R4, and R5 are each independently selected from any one of the following: hydrogen atom, acetoxy group, benzoyl group, tert-butyldimethylsiloxy group, alkoxy group of C1 to C6 (e.g., C1, C2, C3, C4, C5, or C6), and alkoxycarbonyl group of C1 to C8 (e.g., C1, C2, C3, C4, C5, C6, C7, or C8); The third monomer has the structure shown in Formula III: Formula III; In Formula III, R6 is a hydrogen atom or a methyl group, and R7 is selected from alkyl groups of C1 to C12 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12).

[0009] The alkali-soluble polyacrylic acid resin of this invention incorporates some polyphenolic hydroxyl styrene derivative structural units on the resin side groups, which can effectively enhance the etching resistance and adhesion to copper substrates of the photosensitive dry film resist, reducing short circuits and plating problems encountered in circuit board manufacturing processes. The photosensitive dry film resist provided by this invention has excellent adhesion, high resolution, and electroplating resistance. Its phenolic hydroxyl structure provides good water solubility, which helps to accelerate development and stripping speeds, thereby improving production efficiency.

[0010] In this invention, alkali-soluble polyacrylic acid resin plays a decisive role in the photosensitive dry film resist and is a core component of the system. By introducing specific functional groups (hydroxystyrene derivative structure) into the resin structure, many properties of the photosensitive dry film resist, such as adhesion, electroplating resistance and development rate, can be significantly improved.

[0011] As shown in the above structure, the first monomer is (meth)acrylic acid, the second monomer is a styrene derivative, and the third monomer is (meth)acrylate.

[0012] In this invention, the amount of alkali-soluble polyacrylic acid resin used in the photosensitive dry film resist can be 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, 60%, etc., by weight percentage.

[0013] In this invention, the amount of photopolymerizable monomers in the photosensitive dry film resist can be 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, etc., by weight percentage.

[0014] In this invention, the amount of photopolymerization initiator in the photosensitive dry film resist can be 1%, 2%, 3%, 4%, 5%, etc., by weight percentage.

[0015] In this invention, the amount of additives used in the photosensitive dry film resist can be 5%, 6%, 8%, 10%, 12%, 13%, 15%, etc., by weight percentage.

[0016] Preferably, the first monomer is selected from acrylic acid compounds, and more preferably from at least one of acrylic acid or methacrylic acid.

[0017] Preferably, the second monomer is a styrene derivative, and more preferably selected from polyfunctional hydroxystyrene and its derivatives.

[0018] Preferably, the third monomer is selected from at least two of methyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, hydroxyethyl methacrylate, and alkyl methacrylate.

[0019] Preferably, with the total mass of the first monomer, second monomer, and third monomer being 100%, the mass percentage of the first monomer is 10% to 40%, for example, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, etc., and the mass percentage of the second monomer is 5% to 40%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, etc. The percentages of the third monomer are 20% to 85%, such as 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, 60%, 62%, 64%, 65%, 66%, 68%, 70%, 72%, 74%, 75%, 76%, 78%, 80%, 82%, 84%, 85%, etc.

[0020] Preferably, the alkali-soluble polyacrylic acid resin is prepared by the following method: (1) Mix the first monomer, the second monomer, the third monomer, the initiator and the solvent to obtain a mixed solution. Add part of the mixed solution to the reactor and react. Then add the remaining mixed solution and continue the reaction. Increase the temperature and then add the initiator and solvent to react again to obtain the alkali-soluble polyacrylic acid resin precursor. (2) The alkali-soluble polyacrylic acid resin precursor obtained in step (1) is mixed with an organic solvent, and then an alkaline solution is added. The mixture is reacted and then post-treated to obtain the alkali-soluble polyacrylic acid resin.

[0021] Preferably, the initiator in step (1) includes azobisisobutyronitrile and / or azobisisoheptanenitrile.

[0022] Preferably, the total amount of the initiator added in step (1) is 1% to 1.5% of the sum of the masses of the first monomer, the second monomer, and the third monomer, for example, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, etc.

[0023] Preferably, the initiator added in step (1) accounts for 10% to 30% of the total mass of the initiator, for example, 10%, 15%, 20%, 25%, 30%, etc.

[0024] Preferably, the solvent in step (1) includes butanone.

[0025] Preferably, the mixed solution in step (1) accounts for 20% to 40% of the total mass of the mixed solution, for example, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, etc.

[0026] Preferably, the reaction temperature in step (1) is 70~85℃, for example 70℃, 75℃, 80℃, 85℃, etc., and the reaction time is 0.5~2h, for example 0.5h, 1h, 1.5h, 2h, etc.

[0027] Preferably, the temperature for the continued reaction in step (1) is 70~85℃, for example 70℃, 75℃, 80℃, 85℃, etc., and the reaction time is 2~4h, for example 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0028] Preferably, the temperature rise in step (1) is to 88~95℃, such as 88℃, 90℃, 92℃, 93℃, 95℃, etc.

[0029] Preferably, the reaction time in step (1) is 2 to 4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc.

[0030] Preferably, the organic solvent in step (2) includes tetrahydrofuran.

[0031] Preferably, the alkaline solution in step (2) includes an aqueous solution of K2CO3.

[0032] Preferably, the concentration of the alkaline solution in step (2) is 0.05~0.2 mol / L, for example 0.05 mol / L, 0.08 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, etc.

[0033] Preferably, in step (2), the amount of alkaline solution used is 10~30mL, for example, 10mL, 15mL, 20mL, 25mL, 30mL, etc., based on the amount of alkali-soluble polyacrylic acid resin precursor used being 100g.

[0034] Preferably, the reaction temperature in step (2) is 30~50℃, for example 30℃, 35℃, 40℃, 45℃, 50℃, etc., and the reaction time is 5~7h, for example 5h, 6h, 7h, etc.

[0035] Preferably, the post-processing in step (2) includes sedimentation, washing, filtration and drying.

[0036] Preferably, the alkali-soluble polyacrylic acid resin has a weight-average molecular weight of 25,000 to 60,000, such as 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, etc., an acid value of 120 to 250 mg KOH / g, such as 120 mg KOH / g, 140 mg KOH / g, 150 mg KOH / g, 160 mg KOH / g, 180 mg KOH / g, 200 mg KOH / g, 220 mg KOH / g, 240 mg KOH / g, 250 mg KOH / g, etc., and a molecular weight distribution index of 1.2 to 3.0, such as 1.2, 1.5, 1.8, 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3.0, etc. If the acid value of the alkali-soluble polyacrylic acid resin is less than 120 mg KOH / g, there is a tendency for decreased solubility and longer development and stripping times, which may lead to poor resolution. When it exceeds 250 mg KOH / g, it may cause poor resolution due to overdevelopment. The narrow molecular weight distribution of alkali-soluble polyacrylic acid resin is beneficial to improving the resolution of the resist; when the molecular weight distribution is greater than 3, the resolution will deteriorate significantly.

[0037] Preferably, the photopolymerizable monomer is an olefinic unsaturated double bond monomer.

[0038] Preferably, the photopolymerizable monomer is selected from at least one of ethoxylated (propoxylated) nonylphenol acrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated (propoxylated) di(meth)acrylate, ethoxylated (propoxylated) bisphenol A di(meth)acrylate, polyethylene glycol (propylene glycol) di(meth)acrylate, and ethoxylated (propoxylated) carbamate structure (meth)acrylate, and more preferably ethoxylated bisphenol A di(meth)acrylate and / or ethoxylated (propoxylated) nonylphenol acrylate.

[0039] Preferably, the photopolymerization initiator includes any one or a combination of at least two of the following: benzoin ether compounds, benzophenone and its derivatives, thioxanthone series compounds, anthraquinone and its derivatives, thioxanthone series compounds, and hexaaryldiimidazole series compounds.

[0040] Preferably, the benzoin ether compound is selected from any one or a combination of at least two of benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether.

[0041] Preferably, the benzophenone and its derivatives are selected from any one or a combination of at least two of N,N-tetramethyl-4,4-diaminobenzophenone (Michidone), N,N-tetraethyl-4,4-diaminobenzophenone, and 4-methoxy-4-dimethylaminobenzophenone.

[0042] Preferably, the anthraquinone and its derivatives are selected from any one or a combination of at least two of 2-ethylanthraquinone, phenanthraquinone, 2-tert-butylanthraquinone, and octamethylanthraquinone.

[0043] Preferably, the hexaaryl diimidazole series compounds include any one or a combination of at least two of 2,2,4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4,5-diphenyl-1,1-diimidazole, 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, and 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer.

[0044] Preferably, the additive includes any one or a combination of at least two of the following: dyeing agent, plasticizer, defoamer, leveling agent, and polymerization inhibitor.

[0045] Preferably, the staining agent includes any one or a combination of at least two of phthalocyanine green, malachite green, brilliant green, diamond green, methyl violet, crystal violet, methyl green, Victoria blue B, basic green, rhodamine B, and methyl orange.

[0046] Preferably, the plasticizer comprises any one or a combination of at least two of diethyl phthalate, diphenyl phthalate, p-toluenesulfonamide, and dibutyl phthalate.

[0047] Preferably, the polymerization inhibitor comprises any one or a combination of at least two of p-methoxyphenol, hydroquinone, pyrogallol, tert-butylcatechol, and aluminum N-nitrosophenylhydroxylamine.

[0048] The photosensitive dry film resist provided by this invention, in addition to containing alkali-soluble polyacrylic acid resin, photopolymerizable monomers, photopolymerization initiators, and the aforementioned additives, can also contain a certain amount of other types of auxiliaries according to performance requirements. For example, initiators can include 9-phenylacridine, N-phenylglycine, tribromomethylphenyl sulfone, etc.; photochromic agents can include tribromophenyl sulfone, stealth crystal violet, etc.; antioxidants can include 2,6-di-tert-butyl-p-cresol, trinonylphenyl phosphite, etc.; heat stabilizers can include methoxyphenol, hydroquinone, etc.; deodorants can include hydrogenated polydecylene, polyoxyethylene lauryl (dodecyl) ether, etc.; and other additives such as leveling agents and defoamers can also be added. Based on a total dosage of 100 wt.% of the alkali-soluble polyacrylic acid resin and photopolymerizable monomers, the preferred content of each additive is between 0.01 and 20 wt.%. These additives can be used individually or in combination, but are not limited to the use of the above additives.

[0049] In a second aspect, the present invention provides a method for preparing a photosensitive dry film resist as described in the first aspect, the method comprising the following steps: The alkali-soluble polyacrylic acid resin, photopolymerizable monomer, photopolymerization initiator, and additives are mixed in the specified amounts to obtain the photosensitive dry film resist.

[0050] Thirdly, the present invention provides a photosensitive dry film, the photosensitive dry film comprising a resist layer, the resist layer being prepared from the photosensitive dry film resist described in the first aspect.

[0051] For example, the photosensitive dry film is prepared by the following method: Photosensitive dry film resist and solvent are mixed to obtain a resin composition slurry with a solid content of 40%~50%. Using a laboratory-grade small coating device, with appropriate wire bar and coating speed, the above resin composition slurry is uniformly coated on the surface of a PET film with a thickness of 10~20µm. It is then baked in an oven at 80~100℃ for 5~15min. After cooling, a PE film with a thickness of 15~25µm is laminated onto the surface of the dry film resist under certain pressure and temperature to finally obtain a three-layer photosensitive dry film.

[0052] Preferably, the solvent includes any one or a combination of at least two of butanone, acetone, isopropanol, methanol, and ethanol.

[0053] Compared with the prior art, the present invention has the following beneficial effects: (1) The alkali-soluble polyacrylic acid resin of the present invention introduces some polyphenol hydroxy styrene derivative structural units on the resin side group, which can effectively enhance the etching resistance and adhesion of the photosensitive dry film resist to the copper substrate, and reduce the short circuit and plating problems encountered in the circuit board manufacturing process.

[0054] (2) The photosensitive dry film resist provided by the present invention has excellent adhesion (9~13µm), high resolution (9~13µm) and electroplating resistance. It has a phenolic hydroxyl structure and good water solubility, which is beneficial to accelerate the development and stripping speed (stripping speed: 28~32s) and improve production efficiency. Detailed Implementation

[0055] This invention provides a novel structure and preparation method of an alkali-soluble polyacrylic acid resin, as well as a photosensitive dry film resist with high adhesion, high resolution, electroplating resistance, and rapid development prepared from the resin. The invention is described in more detail below through examples; however, these examples are for illustrative purposes only and are not intended to limit the invention to its scope.

[0056] Synthesis example 1 This synthetic example provides a 3,4-diacetoxystyrene, and the synthetic route is shown below: The specific synthesis steps are as follows: In a three-necked flask equipped with a thermometer, a stirrer, and a reflux reflux device, 150 g of N,N-dimethylformamide, 20 g of caffeic acid, and 10 g of triethylamine were added sequentially. The reaction apparatus was placed in an oil bath at 100°C and reacted for 2 h. After that, the mixture was allowed to cool naturally to room temperature.

[0057] After the reaction was completed, the reaction solution was poured into 500 mL of water and extracted three times with 100 mL of dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous magnesium sulfate, filtered, and concentrated to obtain the crude product. The crude product was separated on an organosilicone column using a mixed solvent of petroleum ether and ethyl acetate (10:1) as the developing solvent. After drying, the intermediate product 3,4-dihydroxystyrene was obtained.

[0058] In a three-necked flask equipped with a thermometer and a stirrer, the reaction apparatus was placed in an ice bath at 0°C. 100 g of N,N-dimethylformamide, 10 g of the intermediate product 3,4-dihydroxystyrene, and 10 g of acetic anhydride were added sequentially. After reacting at room temperature for 2 hours, 1 g of HCl was added to terminate the reaction. After the reaction was complete, the reaction solution was poured into 500 mL of water and extracted three times with 100 mL of dichloromethane. The combined organic phases were washed with saturated NaHCO3, dried over anhydrous magnesium sulfate, filtered, and concentrated to obtain the crude product. The crude product was separated on an organosilicone column using a petroleum ether:ethyl acetate (20:1) mixture as the developing solvent. After drying, the target product, 3,4-diacetoxystyrene, was obtained.

[0059] Preparation Example 1 This preparation example provides an alkali-soluble polyacrylic acid resin, which is prepared by solution free radical polymerization. The preparation method includes the following steps: (1) Synthesis of alkali-soluble polyacrylic acid resin precursor The synthesis route is shown below: The synthesis steps are as follows: Weigh out the first, second, and third monomer raw materials according to the following ratio: methacrylic acid / 3,4-diacetoxystyrene / methyl methacrylate / ethyl acrylate = 20 / 5 / 45 / 30, totaling 100g. Mix thoroughly, then add 1g of initiator (AIBN) and 100g of butanone, stir to dissolve, and mix thoroughly. Add the 30% (w / w) mixed solution to a four-necked flask equipped with nitrogen protection and a reflux condenser using a peristaltic pump. Heat the flask to 80°C in an oil bath and stir for 1 hour. Then, slowly add the remaining mixed solution dropwise over 2 hours. Continue the reaction at this temperature for 3 hours, then raise the temperature to 90°C and add 20g of butanone solution containing 0.2g of initiator. After the addition is complete, maintain the temperature and stir for 3 hours to stop the reaction, obtaining an alkali-soluble polyacrylic acid resin precursor.

[0060] (2) Deprotection of alkali-soluble polyacrylic acid resin precursor The synthesis route is shown below: The synthesis steps are as follows: In a four-necked reaction flask, after setting up a stirrer, reflux evaporator, and thermometer, accurately weigh 100 g of alkali-soluble polyacrylic acid resin precursor and 100 mL of tetrahydrofuran. Turn on the stirrer and, after the precursor is completely dissolved, add 20 mL (0.1 M) of K2CO3 aqueous solution. Heat the mixture in an oil bath to 40°C and react for 6 hours. After precipitation with n-hexane, washing with water, filtration, and drying, alkali-soluble polyacrylic acid resin (denoted as alkali-soluble polyacrylic acid resin A) is obtained. Measure its molecular weight, distribution, and acid value.

[0061] Preparation Examples 2-6 (1) Alkali-soluble polyacrylic acid resin precursors A1-A6 were synthesized respectively. The only difference from step (1) of preparation example 1 is that the monomer types and / or amounts are different, as shown in Table 1. (2) Deprotection of alkali-soluble polyacrylic acid resin precursors to synthesize alkali-soluble polyacrylic acid resins B1-B6, which is the same as step (1) of preparation example 1. The molecular weight, distribution and acid value of the obtained alkali-soluble polyacrylic acid resins are shown in Table 2.

[0062] Comparative preparation examples 1-3 Alkali-soluble polyacrylic acid resin precursors A7-A9 were synthesized separately. The only difference from step (1) of preparation example 1 was the type and / or amount of monomers used, as shown in Table 1.

[0063] Table 1 Table 2 Unless otherwise specified, the following raw material information for the embodiments and comparative examples of this invention is as follows: (1) Alkali-soluble polyacrylic acid resins B1-B6 provided in Preparation Examples 1-6 and alkali-soluble polyacrylic acid resin precursors A7-A9 provided in Comparative Preparation Examples 1-3; (2) Photopolymerizable monomer C C1: Ethyltrimethylolpropane triacrylate, molecular weight 428 (Sartoma); C2: Ethyl oxynonylphenol acrylate, molecular weight 626 (Sartoma); C3: Dimethacrylate ethoxylate, molecular weight 598 (Meiyuan); (4) Photopolymerization initiator D D1: 2,2,4-Tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4,5-diphenyl-1,1-diimidazole (Suzhou Weisipu New Materials Co., Ltd.); D2: 9-Phenylacetidine (Suzhou Weisipu New Materials Co., Ltd.); (5) Additive E E1: Stealth Crystal Violet (Shanghai Bailingwei Chemical Technology Co., Ltd.); E2: Diamond Green GH (Shanghai Tixi Chemical Industry Development Co., Ltd.); E3: Tribromomethylphenyl sulfone (Shanghai TCI Chemical Industry Development Co., Ltd.); E4: p-Toluenesulfonamide (Adamas reagent); E5: 2,6-Di-tert-butyl-p-cresol (Shanghai Bailingwei Chemical Technology Co., Ltd.)

[0064] Example 1 This embodiment provides a photosensitive dry film resist, the components and amounts (parts by weight) of which are shown in Table 3.

[0065] The preparation method includes the following steps: The alkali-soluble polyacrylic acid resin, photopolymerizable monomer, photopolymerization initiator, and additives are mixed in the specified amounts to obtain the photosensitive dry film resist.

[0066] Examples 2-6, Comparative Examples 1-3 The only difference from Example 1 is that the specific components and / or amounts are different, as shown in Table 3.

[0067] Table 3 Preparation of photosensitive dry film The photosensitive dry film resists provided in the examples and comparative examples were poured into containers, acetone was added, and the mixture was thoroughly mixed using a stirring device to obtain a resin composition slurry with a solid content of 45%. Using a laboratory-grade small coating apparatus, the resin composition slurry was uniformly coated onto the surface of a 15µm thick PET film and baked in a 90°C oven for 10 minutes. After cooling, an 18µm thick PE film was laminated onto the dry film resist surface to finally obtain a three-layer photosensitive dry film.

[0068] Performance testing Sample preparation method [Screen protector] The copper surface of the copper-clad laminate is deeply polished using a grinding machine. After washing and drying, a bright, uniform, and clean copper surface is obtained. Then, a laminating machine is used to perform heat bonding and film application under standard pressure, with the pressure roller temperature set at 110℃ and the conveying speed at 1.6 m / min.

[0069]

exposure

[0070]

development

[0071] [Removal of film] A 3% (w / v) NaOH aqueous solution was prepared as the stripping solution. The stripping temperature was 60℃ and the pressure was 1.2 kg / cm². 2 The minimum time required for the photosensitive dry film to completely dissolve in the exposed area is taken as the minimum stripping time. The stripping time is 1.5 times the minimum stripping time. After stripping, the film is washed with water and dried.

[0072] Evaluation methods [Electroplating Resistance Evaluation] The temperature was set to 40℃. The developed substrate was immersed in a 10% acidic degreasing solution for 10 minutes, followed by a 5-minute water rinse. After micro-etching with sodium sulfate solution, it was immersed in a 10% sulfuric acid aqueous solution at 25℃ for 2 minutes. The substrate was then immersed in a pre-prepared copper plating solution for 60 minutes; followed by immersion in a 10% sulfuric acid aqueous solution at 25℃ for 2 minutes, and then immersed in a pre-prepared tin plating solution for 10 minutes. After rinsing, the cured dry film was removed, and the morphology and appearance of the dry film sample were observed using a high-resolution scanning electron microscope to check for plating penetration.

[0073] [Resolution Evaluation] Exposure is performed using a mask with a wiring pattern having a 1:1 width ratio between the exposed and unexposed portions. After development at 1.5 times the minimum development time, the minimum mask width that normally forms the cured resist lines is used as the resolution value.

[0074] [Adhesion Evaluation] Photosensitive dry film resist is laminated onto a copper plate by hot pressing. Exposure is performed using a mask with a wiring pattern of n:400, which has exposed and unexposed portions. After development at 1.5 times the minimum development time, the minimum mask width that normally forms cured resist lines is taken as the adhesion value.

[0075] Post-etching adhesion The developed copper plate was then etched using copper chloride as the etching solution at a rate of 1.0 m / min, a temperature of 50°C, an acidity of 2 mol / L, and a copper ion concentration of 140 g / L. The adhesion after etching was determined by observing the etching process with a magnifying glass, using the minimum mask width of the cured resist lines as the value. The resist lines were required to exhibit no lifting or flaking at their edges.

[0076] [Flexibility Evaluation] After lamination, exposure, and development, the flexible substrate is folded 20 times from different angles. The dry film is then observed for cracking, and the number of cracks is counted. The result is expressed numerically; the smaller the number, the better the flexibility of the dry film. (Good: 0-1 cracks after folding; Average: 2-5 cracks after folding; Poor: more than 5 cracks after folding.) The performance test results are shown in Table 4.

[0077] Table 4 As shown in Table 4, Examples 1-6 all yielded photosensitive dry film resists with excellent electroplating resistance, high resolution (9-13µm), high adhesion (9-13µm), good flexibility, and fast stripping speed (28-32s). Comparison with Comparative Examples 1-3 revealed that introducing a certain amount of dihydroxybenzene ring structures into the resin backbone of Examples 1-6 significantly improved the electroplating resistance, resolution, and stripping speed of the photosensitive dry film, demonstrating superior performance. Comparison of Examples 1-6 shows that the resin content has a significant impact on resolution and adhesion, reaching its optimal value at a resin content of 50%.

[0078] In summary, this invention provides an alkali-soluble polyacrylic acid resin that is resistant to electroplating, has high resolution, and high adhesion. The photosensitive dry film resist prepared from this resin can further improve the production quality and efficiency of PCBs.

[0079] The applicant declares that this invention illustrates the photosensitive dry film resist, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A photosensitive dry film resist, characterized in that, The photosensitive dry film resist comprises the following components by weight percentage: Alkali-soluble polyacrylic acid resin 40%~60%; Photopolymerizable monomers 30%~50%; Photopolymerization initiator 1%~5%; Additives 5%~15%; The alkali-soluble polyacrylic acid resin is obtained by reacting a first monomer, a second monomer, and a third monomer. The first monomer has the structure shown in Formula I: Equation I; In Formula I, R1 is a hydrogen atom or a methyl group; The second monomer has the structure shown in Formula II: Formula II; In Formula II, R2 is a hydrogen atom or a methyl group, and R3, R4, and R5 are each independently selected from any one of hydrogen atom, acetoxy group, benzoyl group, tert-butyldimethylsiloxy group, C1-C6 alkoxy group, and C1-C8 alkoxycarbonyl group. The third monomer has the structure shown in Formula III: Formula III; In Formula III, R6 is a hydrogen atom or a methyl group, and R7 is selected from C1 to C12 alkyl groups.

2. The photosensitive dry film resist according to claim 1, characterized in that, The first monomer is selected from acrylic acid compounds, preferably from at least one of acrylic acid or methacrylic acid; Preferably, the second monomer is a styrene derivative, and more preferably selected from polyfunctional hydroxystyrene and its derivatives. Preferably, the third monomer is selected from at least two of methyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, hydroxyethyl methacrylate, and alkyl methacrylate. Preferably, with the total mass of the first monomer, the second monomer, and the third monomer being 100%, the mass percentage of the first monomer is 10% to 40%, the mass percentage of the second monomer is 5% to 40%, and the mass percentage of the third monomer is 20% to 85%.

3. The photosensitive dry film resist according to claim 1 or 2, characterized in that, The alkali-soluble polyacrylic acid resin is prepared by the following method: (1) Mix the first monomer, the second monomer, the third monomer, the initiator and the solvent to obtain a mixed solution. Add part of the mixed solution to the reactor and react. Then add the remaining mixed solution and continue the reaction. Increase the temperature and then add the initiator and solvent to react again to obtain the alkali-soluble polyacrylic acid resin precursor. (2) The alkali-soluble polyacrylic acid resin precursor obtained in step (1) is mixed with an organic solvent, and then an alkaline solution is added. The mixture is reacted and then post-treated to obtain the alkali-soluble polyacrylic acid resin.

4. The photosensitive dry film resist according to claim 3, characterized in that, The initiator in step (1) includes azobisisobutyronitrile and / or azobisisoheptanenitrile; Preferably, the total amount of the initiator added in step (1) accounts for 1% to 1.5% of the sum of the masses of the first monomer, the second monomer, and the third monomer; Preferably, the initiator added in step (1) accounts for 10% to 30% of the total mass of the initiator; Preferably, the solvent in step (1) includes butanone; Preferably, the portion of the mixed solution in step (1) accounts for 20% to 40% of the total mass of the mixed solution; Preferably, the reaction temperature in step (1) is 70~85℃, and the reaction time is 0.5~2h; Preferably, the temperature for the continued reaction in step (1) is 70~85℃, and the reaction time is 2~4h; Preferably, the heating in step (1) is to raise the temperature to 88~95℃; Preferably, the reaction time in step (1) is 2 to 4 hours.

5. The photosensitive dry film resist according to claim 3 or 4, characterized in that, The organic solvent in step (2) includes tetrahydrofuran; Preferably, the alkaline solution in step (2) comprises an aqueous solution of K2CO3; Preferably, the concentration of the alkaline solution in step (2) is 0.05~0.2 mol / L; Preferably, in step (2), the amount of alkaline solution used is 10~30mL, based on the amount of alkali-soluble polyacrylic acid resin precursor used being 100g. Preferably, the reaction temperature in step (2) is 30~50℃ and the reaction time is 5~7h; Preferably, the post-processing in step (2) includes sedimentation, washing, filtration and drying.

6. The photosensitive dry film resist according to any one of claims 1-5, characterized in that, The alkali-soluble polyacrylic acid resin has a weight-average molecular weight of 25,000 to 60,000, an acid value of 120 to 250 mg KOH / g, and a molecular weight distribution index of 1.2 to 3.

0.

7. The photosensitive dry film resist according to any one of claims 1-6, characterized in that, The photopolymerization monomer is an olefinic unsaturated double bond monomer; Preferably, the photopolymerizable monomer is selected from at least one of ethoxylated (propoxylated) nonylphenol acrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated (propoxylated) di(meth)acrylate, ethoxylated (propoxylated) bisphenol A di(meth)acrylate, polyethylene glycol (propylene glycol) di(meth)acrylate, and ethoxylated (propoxylated) carbamate structure (meth)acrylate, and more preferably ethoxylated bisphenol A di(meth)acrylate and / or ethoxylated (propoxylated) nonylphenol acrylate.

8. The photosensitive dry film resist according to any one of claims 1-7, characterized in that, The photopolymerization initiator includes any one or a combination of at least two of the following: benzoin ether compounds, benzophenone and its derivatives, thioxanthone series compounds, anthraquinone and its derivatives, thioxanthone series compounds, and hexaaryldiimidazole series compounds; Preferably, the additive includes any one or a combination of at least two of the following: dyeing agent, plasticizer, defoamer, leveling agent, and polymerization inhibitor.

9. A method for preparing a photosensitive dry film resist as described in any one of claims 1-8, characterized in that, The preparation method includes the following steps: The alkali-soluble polyacrylic acid resin, photopolymerizable monomer, photopolymerization initiator, and additives are mixed in the specified amounts to obtain the photosensitive dry film resist.

10. A photosensitive dry film, characterized in that, The photosensitive dry film includes a resist layer, which is prepared from the photosensitive dry film resist of any one of claims 1-8.

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