A photosensitive resin composition, a method for preparing the same, and a method for using the same

Abstract

The present application relates to a photosensitive resin composition, and particularly relates to a photosensitive resin composition and a preparation method and application thereof, raw materials for preparation include 30-60 parts of alkali-soluble modified binder resin, 20-53 parts of photopolymerizable monomer, 0.1-10 parts of hydrophobic photoinitiator and 0.5-5 parts of functional additive by weight; the preparation raw materials of the alkali-soluble modified binder resin include mixed monomers, solvent and initiator A; the mixed monomers include 15-30% carboxyl monomer, 20-40% rigid alicyclic monomer and 5-25% long-chain alkyl acrylate monomer based on 100% of the total weight of the mixed monomers; the carbon chain length of the long-chain alkyl acrylate monomer is C8-C22. The present application provides a photosensitive resin composition which can maintain excellent alkali water developing characteristics, has moisture resistance after curing, and has high resolution and good mechanical properties.

Description

Technical Field

[0001] This invention relates to photosensitive resin compositions, and more specifically to a photosensitive resin composition, its preparation method, and its application. Background Technology

[0002] Since DuPont invented dry film photoresist in the late 1960s, this material has revolutionized the manufacturing process of electronic circuits. Compared to traditional liquid photoresist, dry film photoresist, with its unique "sandwich" structure—a polyester (PET) support film, a photosensitive resin layer, and a polyethylene (PE) protective film—offers superior thickness uniformity, a simplified process flow (eliminating the need for coating and baking equipment), and excellent via masking capabilities.

[0003] Over the past few decades, dry film photoresists have undergone technological iterations, evolving from solvent-developable to semi-aqueous developable, and finally to all-aqueous alkaline developable. Currently, mainstream dry film photoresists use a dilute sodium carbonate solution (typically 1% Na₂CO₃) as the developer, which not only reduces production costs but also significantly reduces environmental pollution from organic solvent emissions. To achieve this characteristic, the core film-forming resin in the dry film formulation must contain sufficient carboxyl groups (-COOH) to ensure that unexposed areas can undergo an acid-base neutralization reaction with the weak base and dissolve.

[0004] As electronic devices become thinner, lighter, and more multifunctional, the wiring density of PCBs and IC substrates is increasing exponentially. Current modified semi-additive process (mSAP) technology has pushed the line width / spacing (L / S) to 15 / 15 μm or even lower. At such a fine pitch, even tiny defects in the insulating material can be amplified by the electric field, leading to serious reliability issues.

[0005] The core challenge of existing all-water developable dry-film photoresists lies in the fact that, to ensure development speed and cleanliness, the resin must retain hydrophilic groups with a high acid value (typically 100-250 mgKOH / g). However, these hydrophilic groups remain in the cured film, becoming adsorption sites and transport channels for water molecules. Under high-temperature and high-humidity environments (such as 85℃ / 85%RH), or in subsequent wet processes such as electroless nickel-gold plating (ENIG) and immersion tin, moisture will penetrate into the film and the resist / copper interface along these hydrophilic channels. This hygroscopic behavior leads to problems such as decreased interfacial adhesion, electrochemical migration (ECM), dendrite growth, and high-frequency signal loss.

[0006] Chinese invention patent application CN118625599A discloses a photosensitive resin composition. This invention increases photosensitivity by introducing a specific photosensitive unit structure into a conventional anthracene sensitizer. Combined with suitable alkali-soluble resin, photopolymerizable monomers and other components, the resulting photosensitive resin composition meets the application requirements of high resolution, high adhesion and high thickness in high-precision IC substrate manufacturing and special application scenarios. However, its moisture resistance has not been effectively improved. Summary of the Invention

[0007] To address the problems in the prior art, the first aspect of the present invention provides a photosensitive resin composition, wherein, by weight, the raw materials include 30-60 parts of alkali-soluble modified adhesive resin, 20-53 parts of photopolymerizable monomer, 0.1-10 parts of hydrophobic photoinitiator, and 0.5-5 parts of functional additives. The raw materials for preparing the alkali-soluble modified adhesive resin include: mixed monomers, solvent and initiator A; based on the total weight of the mixed monomers as 100%, the mixed monomers include 15-30% carboxyl monomers, 20-40% rigid alicyclic monomers, 5-25% long-chain alkyl acrylate monomers, and the base monomers make up the balance. The carbon chain length of the long-chain alkyl acrylate monomer is C8-C22.

[0008] This invention grafts long-chain alkyl acrylate monomers and rigid alicyclic monomers onto an alkali-soluble adhesive resin. On one hand, during the development stage, carboxyl groups are uniformly distributed across the polymer chains, ensuring solubility in the alkaline solution. After drying and curing, the long-chain alkyl groups, due to their low surface energy, tend to migrate and orient towards the film surface and the interior of the free volume, forming a hydrophobic protective layer that physically shields the hydrophilic carboxyl groups from water molecule attack. On the other hand, the rigid alicyclic structure synergistically with the long-chain alkyl monomers to form "hydrophobic microregions" in the cured film, physically blocking water molecule penetration pathways. Furthermore, the rigid alicyclic structure, with its high three-dimensional volume and rigid framework, effectively restricts the swelling movement of the polymer chains during development, reducing lateral diffusion. Simultaneously, the rigid framework provides strength while the flexible segments provide toughness, avoiding the risk of brittleness.

[0009] This invention ensures that the material possesses good flexibility and processing properties without reducing hydrophobicity by controlling the amount of carboxyl monomers, rigid alicyclic monomers, long-chain alkyl acrylate monomers, and basic monomers.

[0010] In some embodiments, the rigid alicyclic monomer includes at least one of isobornyl methacrylate, tricyclodecane methacrylate, or adamantane methacrylate.

[0011] In some embodiments, the long-chain alkyl acrylate monomer includes at least one of lauryl methacrylate, stearyl methacrylate, isodecanyl methacrylate, 2-ethylhexyl methacrylate, and behenyl methacrylate.

[0012] In some embodiments, the alkali-soluble modified adhesive resin satisfies at least one of the following characteristics: (1) The amount of solvent used is 120-200% of the total weight of the mixed monomers; (2) The weight-average molecular weight of the alkali-soluble modified adhesive resin is 40,000-100,000 g / mol; (3) The acid value of the alkali-soluble modified adhesive resin is 130-160 mg KOH / g.

[0013] In some embodiments, the photopolymerizable monomer includes hydrophobic acrylates, which include at least one of ethoxylated trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, nonylphenol polyoxyethylene ether acrylate, tricyclodecanediethanol diacrylate, or polyurethane acrylate.

[0014] In some embodiments, the hydrophobic photoinitiator includes a HABI (hexaaryldiimidazole) initiator, a sensitizer, and a co-initiator, wherein the mass ratio of the HABI initiator, sensitizer, and co-initiator is (2.5-3):(0.8-1.2):(0.7-0.8).

[0015] Optionally, the HABI initiator includes 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-bisimidazole.

[0016] Optionally, the sensitizer includes 9-phenylacridine or 4,4'-diethylaminobenzophenone.

[0017] Optionally, the co-initiator includes at least one of N-phenylglycine and 2-mercaptobenzothiazole.

[0018] This invention uses hydrophobic acrylates and hydrophobic photoinitiators to form a high cross-linking density network in the exposure area, further locking hydrophilic groups, reducing free volume, and blocking ion migration channels. The lophyl radicals generated after photolysis of HABI-type initiators are hydrophobic and do not release gas, avoiding micropore defects. The co-initiator acts as a hydrogen donor to improve initiation efficiency, while forming a complex film with copper to prevent oxidation. Furthermore, the compounding of hydrophobic photoinitiator raw materials ensures high response to 355nm / 405nm lasers, meeting the production capacity requirements of high-speed direct-write exposure.

[0019] In some embodiments, the functional additives include at least one of color developers, dyes, polymerization inhibitors, and adhesion promoters.

[0020] Optionally, the polymerization inhibitor includes at least one of hydroquinone monomethyl ether and aluminum nitrosophenyl hydroxylamine.

[0021] Optionally, the adhesion promoter includes at least one of benzotriazole, 5-aminotetrazole, or a silane coupling agent.

[0022] Optionally, the color developer includes colorless crystal violet.

[0023] Optionally, the dye may include Victoria Blue or Malachite Green.

[0024] In some embodiments, the alkali-soluble modified adhesive resin satisfies at least one of the following characteristics: (1) The carboxyl monomer includes methacrylic acid or acrylic acid; (2) The basic monomer includes at least one of methyl methacrylate, styrene, or butyl acrylate; (3) The solvent includes propylene glycol monomethyl ether acetate and methyl ethyl ketone, and the mass ratio of propylene glycol monomethyl ether acetate to methyl ethyl ketone is (2-3):(1-2); (4) The weight-average molecular weight of the alkali-soluble modified adhesive resin is 40,000-100,000 g / mol, and the acid value is 130-160 mg KOH / g.

[0025] Optionally, the base monomers include methyl methacrylate, styrene, and butyl acrylate, wherein the mass ratio of methyl methacrylate, styrene, and butyl acrylate is (20-25):10:(8-10).

[0026] A second aspect of the present invention provides a method for preparing a photosensitive resin composition, comprising at least the following steps: S1. Mix the mixed monomers and 0.5wt% initiator evenly and then add them dropwise to the solvent. After the addition is complete, keep the temperature for 2-3 hours, add the remaining initiator and heat to react. After cooling, the alkali-soluble modified adhesive resin is obtained. S2. The alkali-soluble modified adhesive resin is mixed with photopolymerizable monomers, hydrophobic photoinitiators and functional additives in a light-protected environment, and then filtered to obtain the photosensitive resin composition.

[0027] In some embodiments, the dripping time in S1 is 3-4 hours.

[0028] In some implementations, S2 includes: S21. Add dye, color developer and adhesion promoter to the alkali-soluble modified adhesive resin, disperse until completely dissolved, to obtain a mixed solution; S22. Add a photopolymerizable monomer, a hydrophobic photoinitiator, and a polymerization inhibitor to the mixed solution, stir and mix in a light-protected environment, and then pass the mixture through 5μm and 1μm polypropylene depth filters in sequence to obtain the photosensitive resin composition.

[0029] In some embodiments, the rotational speed dispersed in S21 is 1500 rpm.

[0030] In some embodiments, the stirring speed in S22 is <500 rpm.

[0031] A third aspect of the present invention provides the application of a photosensitive resin composition in the preparation of a photosensitive dry film.

[0032] The method for preparing the photosensitive dry film includes: uniformly coating the photosensitive resin composition onto a PET film, drying it, hot-pressing it to form a PE protective film, and then winding it into a roll to obtain the photosensitive dry film.

[0033] In some embodiments, the coating thickness is 15-50 μm.

[0034] In some embodiments, the drying process is a three-stage drying process, specifically including: drying at 60-80℃ for 3-8 minutes, then raising the temperature to 80-95℃ for 5-10 minutes, and finally raising the temperature to 100-115℃ for 3-8 minutes.

[0035] Beneficial effects 1. This invention grafts long-chain alkyl acrylate monomers and rigid alicyclic monomers onto an alkali-soluble adhesive resin, achieving moisture resistance similar to that of hydrophobic materials without using fluorine-containing or organosilicon compounds. In an 85°C / 85%RH bias test, the insulation resistance remains at 10 ohms. 11 With a strength of Ω or higher, the risk of copper dendrite growth is completely eliminated, greatly improving the long-term reliability of 5G communication boards and automotive circuit boards.

[0036] 2. The introduction of the rigid alicyclic structure in this invention significantly reduces lateral swelling during the development process. Actual measurements show a resolution of L / S = 6 / 6 μm, perfectly suited for ultra-fine circuit manufacturing processes such as mSAP and SAP.

[0037] 3. The long-chain alkyl group of this invention provides internal plasticizing effect, reduces the rigidity of the molecular chain, and avoids the brittleness of the film caused by simple alicyclic monomers; at the same time, its hydrophobicity and side chain shielding effect work together to resolve the contradiction between rigidity and flexibility.

[0038] 4. The photosensitive resin composition provided by the present invention has a high response to 355nm / 405nm lasers, which meets the production capacity requirements of high-speed direct writing exposure.

[0039] 5. The dense hydrophobic cross-linked network of the photosensitive resin composition provided by the present invention effectively blocks the penetration of strong acid solutions such as electroless nickel plating and immersion tin plating, solving the industry pain points of seepage plating and coating peeling.

[0040] 6. This invention does not contain expensive fluorine monomers, does not contain easily polluting silicone oils, and the all-water development process conforms to the environmental trend of green manufacturing. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention. Experimental methods not specifying specific conditions in the embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0042] The raw material information for each embodiment and comparative example is shown below: (1) HABI initiator 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-bisimidazole: model BCIM (B-CIM), Changzhou Qiangli Electronic New Materials Co., Ltd., CAS No. 7189-82-4; (2) Sensitizer 4,4'-diethylaminobenzophenone: Model EAB, Changzhou Qiangli Electronic New Materials Co., Ltd., CAS No. 90-93-7; (3) Co-initiator N-phenylglycine: Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 103-01-5; (4) Co-initiator 2-mercaptobenzothiazole: Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 149-30-4; (5) Initiator A: Azobisisobutyronitrile (AIBN), Shanghai Maclean Biochemical Technology Co., Ltd., CAS No. 78-67-1; (6) Polymer inhibitor hydroquinone monomethyl ether (MEHQ): Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 150-76-5; Nitrosylphenyl hydroxylamine aluminum salt (Q-1301): from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 15305-07-4; (7) Adhesion promoter benzotriazole: Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 95-14-7; KBM-403 silane coupling agent: Shin-Etsu Chemical Co., Ltd., CAS No. 2530-83-8.

[0043] (8) Sensitizer 9-phenylacridine: CAS No. 602-56-2, from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0044] Example 1 The first aspect of this example provides a photosensitive resin composition, which, by weight, comprises 45 parts of alkali-soluble modified adhesive resin, 49 parts of photopolymerizable monomer, 4 parts of hydrophobic photoinitiator, and 2 parts of functional additives.

[0045] The raw materials for preparing the alkali-soluble modified adhesive resin, by weight, include: 100 parts of mixed monomers, 150 parts of solvent and 2 parts of initiator A.

[0046] Based on the total weight of the mixed monomers as 100%, the mixed monomers include 22% carboxyl monomers, 25% rigid alicyclic monomers, 10% long-chain alkyl acrylate monomers, and the base monomers make up the balance.

[0047] The carboxyl monomer is methacrylic acid; The rigid alicyclic monomer is isobornyl methacrylate; The long-chain alkyl acrylate monomer is lauryl methacrylate; The basic monomers are methyl methacrylate, styrene, and butyl acrylate in a mass ratio of 25:10:8.

[0048] The solvent is propylene glycol monomethyl ether acetate and methyl ethyl ketone, and the mass ratio of propylene glycol monomethyl ether acetate to methyl ethyl ketone is 3:2.

[0049] The photopolymerizable monomers include ethoxylated trimethylolpropane triacrylate, tricyclodecanediethanol diacrylate, and nonylphenol polyoxyethylene ether acrylate, wherein the mass ratio of ethoxylated trimethylolpropane triacrylate, tricyclodecanediethanol diacrylate, and nonylphenol polyoxyethylene ether acrylate is 25:15:9.

[0050] The hydrophobic photoinitiator includes a HABI-type initiator, a sensitizer, and a co-initiator, wherein the mass ratio of the HABI-type initiator, the sensitizer, and the co-initiator is 2.5:0.8:0.7.

[0051] The HABI initiator is 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-bisimidazole.

[0052] The sensitizer is 9-phenylacridine.

[0053] The co-initiator is N-phenylglycine and 2-mercaptobenzothiazole, with a mass ratio of 5:2.

[0054] The functional additives include color developers, dyes, polymerization inhibitors, and adhesion promoters, and the mass ratio of the color developers, dyes, polymerization inhibitors, and adhesion promoters is 0.5:0.05:0.2:1.25.

[0055] The color developer is colorless crystal violet; The dye is Victoria Blue; The polymerization inhibitor is hydroquinone monomethyl ether and aluminum nitrosophenylhydroxylamine salt, and the mass ratio of hydroquinone monomethyl ether to aluminum nitrosophenylhydroxylamine salt is 3:1.

[0056] The adhesion promoter is benzotriazole and KBM-403 silane coupling agent, and the mass ratio of benzotriazole and KBM-403 silane coupling agent is 8:4.5.

[0057] The initiator A is azobisisobutyronitrile.

[0058] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 65,000 g / mol and an acid value of 148 mg KOH / g.

[0059] The second aspect of this example provides a method for preparing a photosensitive resin composition, comprising the following steps: S1. Mix the mixed monomers and 50wt% initiator evenly at 80℃ and then dropwise into the solvent. After the uniform dropwise addition is completed in 3.5h, keep warm for 2h, add the remaining initiator, raise the temperature to 90℃ and continue the reaction for 2h. After cooling, the alkali-soluble modified adhesive resin is obtained. S21. Add dye, color developer and adhesion promoter to the alkali-soluble modified adhesive resin, disperse at 1500 rpm until completely dissolved to obtain a mixed solution; S22. Add a photopolymerizable monomer, a hydrophobic photoinitiator, and a polymerization inhibitor to the mixed solution. After stirring and mixing at 400 rpm in a light-protected (yellow light zone) environment, pass the mixture through 5 μm and 1 μm polypropylene depth filters in sequence to obtain the photosensitive resin composition.

[0060] The third aspect of this example provides an application of a photosensitive resin composition in the preparation of photosensitive dry films.

[0061] The preparation method of the photosensitive dry film includes: uniformly coating the photosensitive resin composition onto a PET film with a coating thickness of 35 μm, drying and then hot-pressing it to form a PE protective film, and then winding it into a roll to obtain the photosensitive dry film.

[0062] The drying process employs a three-stage drying method, specifically: drying at 70°C for 5 minutes, followed by drying at 90°C for 7 minutes, and finally drying at 110°C for 5 minutes.

[0063] Example 2 The specific implementation method of this example is the same as that of Example 1, except that, by weight, the raw materials include 40 parts of alkali-soluble modified adhesive resin, 53 parts of photopolymerizable monomer, 5 parts of hydrophobic photoinitiator and 2 parts of functional additives.

[0064] The raw materials for preparing the alkali-soluble modified adhesive resin, by weight, include: 100 parts of mixed monomers, 140 parts of solvent and 2 parts of initiator A.

[0065] Based on the total weight of the mixed monomers as 100%, the mixed monomers include 20% carboxyl monomers, 35% rigid alicyclic monomers, 5% long-chain alkyl acrylate monomers, and the base monomers make up the balance.

[0066] The rigid alicyclic monomer is tricyclodecane methacrylate; The long-chain alkyl acrylate monomer is stearate methacrylate; The basic monomers are methyl methacrylate, styrene, and butyl acrylate in a mass ratio of 20:10:10.

[0067] The solvent is propylene glycol monomethyl ether acetate and methyl ethyl ketone, and the mass ratio of propylene glycol monomethyl ether acetate to methyl ethyl ketone is 17:11.

[0068] The photopolymerizable monomers include dipentaerythritol hexaacrylate, tricyclodecanediethanol diacrylate, and polyurethane acrylate, wherein the mass ratio of dipentaerythritol hexaacrylate, tricyclodecanediethanol diacrylate, and polyurethane acrylate is 30:15:8.

[0069] The hydrophobic photoinitiator includes a HABI-type initiator, a sensitizer, and a co-initiator, wherein the mass ratio of the HABI-type initiator, the sensitizer, and the co-initiator is 3:1.2:0.8.

[0070] The HABI initiator is 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-bisimidazole.

[0071] The sensitizer is 4,4'-diethylaminobenzophenone.

[0072] The co-initiator is N-phenylglycine and 2-mercaptobenzothiazole, with a mass ratio of 5:3.

[0073] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 55,000 g / mol and an acid value of 135 mg KOH / g.

[0074] Example 3 The specific implementation method of this example is the same as that of Example 1, except that: by weight, the raw materials include 30 parts of alkali-soluble modified adhesive resin, 20 parts of photopolymerizable monomer, 0.1 parts of hydrophobic photoinitiator and 0.5 parts of functional additives.

[0075] The raw materials for preparing the alkali-soluble modified adhesive resin, by weight, include: 100 parts of mixed monomers, 120 parts of solvent and 2 parts of initiator A.

[0076] Based on the total weight of the mixed monomers as 100%, the mixed monomers include 15% carboxyl monomers, 20% rigid alicyclic monomers, 5% long-chain alkyl acrylate monomers, and the remaining amount is made up of the base monomers.

[0077] The long-chain alkyl acrylate monomer is 2-ethylhexyl methacrylate (carbon chain length C8). The basic monomers are methyl methacrylate, styrene, and butyl acrylate in a mass ratio of 35:14:11.

[0078] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 45,000 g / mol and an acid value of 132 mg KOH / g.

[0079] The coating thickness of the photosensitive dry film is 25 μm, and the drying conditions are: drying at 65°C for 4 min, then heating to 85°C for 6 min, and finally heating to 105°C for 4 min.

[0080] Example 4 The specific implementation method of this example is the same as that of Example 1, except that, by weight, the raw materials include 60 parts of alkali-soluble modified adhesive resin, 50 parts of photopolymerizable monomer, 10 parts of hydrophobic photoinitiator and 5 parts of functional additives.

[0081] The raw materials for preparing the alkali-soluble modified adhesive resin, by weight, include: 100 parts of mixed monomers, 180 parts of solvent and 2 parts of initiator A.

[0082] Based on the total weight of the mixed monomers as 100%, the mixed monomers include 30% carboxyl monomers, 40% rigid alicyclic monomers, 25% long-chain alkyl acrylate monomers, and the base monomers make up the balance.

[0083] The long-chain alkyl acrylate monomer is behenate methacrylate (carbon chain length C22). The basic monomers are methyl methacrylate, styrene, and butyl acrylate in a mass ratio of 3:1:1.

[0084] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 95,000 g / mol and an acid value of 158 mg KOH / g.

[0085] The coating thickness of the photosensitive dry film is 45 μm, and the drying conditions are: drying at 75°C for 7 min, then heating to 93°C for 9 min, and finally heating to 113°C for 7 min.

[0086] Comparative Example 1 The specific implementation method of this example is the same as that of Example 1, except that, by weight, the raw materials include 45 parts of alkali-soluble modified adhesive resin, 49 parts of photopolymerizable monomer, 4 parts of hydrophobic photoinitiator and 2 parts of functional additives.

[0087] Based on the total weight of the mixed monomers being 100%, the mixed monomers comprise 25% carboxyl monomers and 75% base monomers.

[0088] The basic monomers are methyl methacrylate, styrene, and butyl acrylate in a mass ratio of 40:15:20.

[0089] The photopolymerizable monomers include ethoxylated trimethylolpropane triacrylate and trimethylolpropane triacrylate, wherein the mass ratio of ethoxylated trimethylolpropane triacrylate to trimethylolpropane triacrylate is 30:19.

[0090] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 60,000 g / mol and an acid value of 170 mg KOH / g.

[0091] Comparative Example 2 The specific implementation method in this example is the same as that in Comparative Example 1, except that 2 parts of hydroxyl silicone oil (KF-6001, Shin-Etsu Chemical, hydroxyl value 30mgKOH / g) are added to the formula of Comparative Example 1.

[0092] The weight-average molecular weight of the alkali-soluble modified adhesive resin is 60,000 g / mol, and the acid value is 170 mg KOH / g (same as Comparative Example 1, silicone oil is a post-addition and does not participate in the copolymerization reaction).

[0093] Comparative Example 3 The specific implementation method in this example is the same as that in Comparative Example 1, except that methyl methacrylate, which accounts for 15 wt% of the total amount of mixed monomers, is replaced with trifluoroethyl methacrylate (TFEMA).

[0094] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 62,000 g / mol and an acid value of 170 mg KOH / g.

[0095] Comparative Example 4 The specific implementation method of this example is the same as that of Example 1, except that, based on the total weight of the mixed monomers as 100%, the mixed monomers include 25% carboxyl monomers, 5% rigid alicyclic monomers, 3% long-chain alkyl acrylate monomers, and the base monomers make up the balance.

[0096] The basic monomers are methyl methacrylate, styrene, and butyl acrylate in a mass ratio of 42:10:15.

[0097] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 60,000 g / mol and an acid value of 170 mg KOH / g.

[0098] Comparative Example 5 The specific implementation method of this example is the same as that of Example 2, except that, based on the total weight of the mixed monomers as 100%, the mixed monomers include 22% carboxyl monomers, 60% rigid alicyclic monomers, 0% long-chain alkyl acrylate monomers, and the base monomers make up the balance.

[0099] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 55,000 g / mol and an acid value of 145 mg KOH / g.

[0100] The photosensitive dry film prepared in this example has a glass transition temperature (Tg) exceeding 140°C, resulting in extreme brittleness at room temperature. During the slitting and lamination process, the dry film breaks and sheds a large amount of powder, severely contaminating the cleanroom environment and the laminating machine.

[0101] Comparative Example 6 The specific implementation method in this example is the same as in Example 1, except that the hydrophobic photoinitiator is replaced with benzophenone (BP, CAS 119-61-9, Shanghai McLean Biochemical Technology Co., Ltd.).

[0102] The alkali-soluble modified adhesive resin has a weight-average molecular weight of 65,000 g / mol and an acid value of 148 mg KOH / g (the formulation is the same as in Example 1, only the photoinitiator is different).

[0103] Because the initiator has limited solubility in acrylic resin, a large number of white crystals precipitated on the surface of the dry film after coating and drying. This not only led to uneven exposure but also caused residue after development.

[0104] Performance testing The photosensitive dry films prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to the following tests: 1. Surface hydrophobicity (water contact angle) test: Method: After laminating the photosensitive dry film, exposing the entire plate, and curing, the static contact angle of deionized water was measured using a Goniometer.

[0105] A contact angle >90° indicates significant hydrophobicity, which can effectively repel processing solutions.

[0106] 2. Moisture resistance insulation reliability test: Test standard: IPC-TM-650 2.6.3.3 15.

[0107] Conditions: IPC-B-24 comb circuit, line width / spacing 50 / 50 μm. Environment: 85℃ / 85% RH, DC bias 50V, continuous for 168h.

[0108] Judgment: Resistance value ≥ 1 × 10⁻⁶ after 168 hours 11 Ω indicates a passing grade, and no dendrite growth is observed under a microscope.

[0109] 3. Resolution test: Test method: Exposure and development were performed using a Stouffer 21-level optical wedge and resolution test film.

[0110] Judgment: The minimum line width / line spacing (L / S) that can be clearly developed (no residual glue at the base and no peeling at the top).

[0111] 4. Adhesion test: Test method: Cross-hatch tape test (ASTM D3359).

[0112] Judgment: 5B (no shedding) is excellent, 0B (large area shedding) is poor.

[0113] 5. Chemical resistance to gold plating test: Test method: The developed board is subjected to a standard chemical nickel-gold process.

[0114] Judgment: The appearance of the dry film edge after testing is divided into the following four levels: Excellent: The dry film edge has no plating penetration or lifting, and the boundary is clear and flat; Good: The dry film edge has slight discoloration but no plating penetration, or a local area of ​​no more than 5% of the area has slight lifting but does not affect the function; Lifting: The dry film edge is obviously lifted from the substrate, but the plating solution has not penetrated below; Plating penetration: The plating solution penetrates below the dry film, causing an unwanted plating layer.

[0115] 6. Criteria for determining electrochemical migration / dendritic formation: After the double 85 moisture resistance insulation reliability test, the morphology between adjacent conductors of the IPC-B-24 comb circuit was observed using a metallographic microscope (200×~500×), and divided into the following four levels: None: No dendrite formation was observed between adjacent wires under a microscope; Slight: A small number of isolated, discontinuous fine dendrites are visible. The longest single dendrite does not exceed 1 / 4 of the distance between adjacent conductors (50μm), i.e., ≤12μm; Medium: Multiple dendrites are visible, with some dendrites reaching 1 / 3 to 2 / 3 of the distance between adjacent conductors in length; Severe: Dendrites penetrate or nearly penetrate between adjacent conductors, forming a conductive path and causing a short circuit or near short circuit (synchronous failure of insulation resistance test).

[0116] The test results are shown in Tables 1 and 2.

[0117] Table 1

[0118] Table 2

[0119] As can be seen from Tables 1 and 2, although the traditional formulation (Comparative Example 1) has a fast development speed, its insulation resistance decreases exponentially in the double 85 (moisture resistance insulation reliability) test, and copper dendrites appear, proving that its hydrophilic network cannot block ion migration. In contrast, Examples 1-4 of this application, through hydrophobic modification, although the development time increases slightly (still within an industrially acceptable range), maintains extremely high insulation resistance (>10). 11 Ω), demonstrating the effectiveness of the hydrophobic barrier.

[0120] In Comparative Example 2, while the addition of silicone oil (physical blending) increased the contact angle, the adhesion significantly decreased (5B-3B), and peeling occurred during the chemical gold plating resistance test. This is because the free silicone oil migrated to the copper-adhesive interface, forming a weak boundary layer. This invention avoids this problem by chemically bonding hydrophobic groups to the main chain.

[0121] Comparative Example 3 (fluorine-containing formulation) exhibited extreme hydrophobicity but extremely poor adhesion (0B-1B), causing all fine lines to detach under development stress. This verifies that excessively pursuing low surface energy can sacrifice interfacial bonding. The long-chain alkyl and alicyclic structures of this invention provide hydrophobicity while retaining sufficient van der Waals forces and mechanical interlocking capabilities, achieving a perfect balance.

[0122] Comparative Example 4 reduced the rigid alicyclic monomer to 5 wt% and the long-chain alkyl acrylate monomer to 3 wt%. The results showed that the contact angle was only 68° (far lower than the 105° in Example 1), and the insulation resistance dropped to 10 ohms after 168 hours of double 85 testing. 7 Ω and slight dendrites appeared, degrading the resolution to 15 / 15μm. This fully demonstrates that the content of hydrophobic monomers (rigid alicyclic + long-chain alkyl) must reach the range specified in this invention to achieve the synergistic effect of high hydrophobicity and high reliability.

Claims

1. A photosensitive resin composition, characterized in that, By weight, the photosensitive resin composition comprises 60 parts of alkali-soluble modified adhesive resin, 50 parts of photopolymerizable monomer, 10 parts of hydrophobic photoinitiator and 5 parts of functional additives. The raw materials for preparing the alkali-soluble modified adhesive resin include: mixed monomers, solvent and initiator A; The solvent is propylene glycol monomethyl ether acetate and methyl ethyl ketone; The initiator A is azobisisobutyronitrile; Based on the total weight of the mixed monomers as 100%, the mixed monomers include 30% methacrylic acid, 40% isobornyl methacrylate, 25% benzyl methacrylate, with methyl methacrylate, styrene and butyl acrylate making up the balance, and the mass ratio of methyl methacrylate, styrene and butyl acrylate is 3:1:

1. The photopolymerizable monomers include ethoxylated trimethylolpropane triacrylate, tricyclodecanediethanol diacrylate and nonylphenol polyoxyethylene ether acrylate, with a mass ratio of 25:15:

9. The hydrophobic photoinitiator comprises 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-bisimidazole, 9-phenylacridine, and a co-initiator composed of N-phenylglycine and 2-mercaptobenzothiazole, wherein the mass ratio of 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-bisimidazole, 9-phenylacridine, and the co-initiator is 2.5:0.8:0.7, and the mass ratio of N-phenylglycine to 2-mercaptobenzothiazole is 5:2; The alkali-soluble modified adhesive resin has a weight-average molecular weight of 95,000 g / mol and an acid value of 158 mg KOH / g. The functional additives include at least one of color developers, dyes, polymerization inhibitors, and adhesion promoters.

2. The photosensitive resin composition according to any one of claims 1, characterized in that, The mass ratio of propylene glycol monomethyl ether acetate to methyl ethyl ketone is (2-3):(1-2).

3. A method for preparing the photosensitive resin composition according to any one of claims 1-2, characterized in that, At least the following steps are included: S1. Mix the mixed monomers with 50wt% initiator A evenly and then add them dropwise to the solvent. After the addition is complete, keep the temperature for 2-3 hours, add the remaining initiator A, heat and react, and then cool to obtain the alkali-soluble modified adhesive resin. S2. The alkali-soluble modified adhesive resin is mixed with photopolymerizable monomers, hydrophobic photoinitiators and functional additives in a light-protected environment, and then filtered to obtain the photosensitive resin composition.

4. The use of the photosensitive resin composition according to any one of claims 1-2 in the preparation of photosensitive dry films.

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