Photosensitive resin composition containing anthracene methyl modified melamine photosensitizer, photosensitive dry film and application thereof

Abstract

The invention provides a photosensitive resin composition containing an anthracene methyl modified melamine photosensitizer, a photosensitive dry film and application of the photosensitive dry film, the photosensitizer adopts a melamine skeleton to connect three anthracene 9-methyl structures, and through a rigid structure of the melamine skeleton and a methylene bridging (-CH2-An) design of an anthracene group, the photosensitive resin composition has the remarkable advantages that the methylene bridging structure can be used for preparing a photosensitizer, and the photosensitizer can be used as a photosensitizer for photosensitization of the anthracene methyl modified melamine photosensitizer. The breakage of carbon-oxygen bonds on alkoxy caused by p-pi conjugation is avoided, so that the migration of small molecular fragments after initiation is reduced, permeable crystallization to a polyethylene protective film is effectively inhibited, and the risk of short circuit of a line is remarkably reduced; the light quantum yield can be greatly improved by introducing a plurality of light sensing units; the melamine skeleton is used, so that the adhesive force of the initiation system on the metal foil surface can be effectively improved; in addition, the photosensitizer also shows excellent solubility and formula compatibility, and can be widely applied to the photocuring fields of dry films, paints, coatings, printing inks, molding materials and the like.

Description

Technical Field

[0001] The invention relates to a photosensitive resin composition containing an anthracenemethyl modified melamine photosensitizer, a photosensitive dry film and applications thereof. Background Art

[0002] Photosensitive resin compositions, as key pattern transfer materials, are widely used in the manufacture of printed circuit boards (PCBs), lead frames (LFs), and semiconductor package (IC) substrates. The photosensitive resin composition is typically coated onto a PET support film. After drying, a protective layer, such as a polyethylene (PE) film, is adhered to the surface to form a photosensitive dry film (also known as a dry film resist). The pattern transfer process involves first applying the dry film resist to a copper substrate and then covering it with a patterned mask to expose the pattern. A weakly alkaline aqueous solution is then used as a developer to remove the unexposed areas, followed by etching or electroplating to form the pattern. Finally, a stripping solution is used to remove the cured dry film, completing the pattern transfer.

[0003] As electronic devices progress toward miniaturization and higher density, the demand for circuit fineness continues to increase. To meet the demands of fine circuit manufacturing, photosensitive resin compositions must exhibit higher resolution. To improve resolution, appropriate sensitizers must be added to the photosensitive resin composition. For photosensitive resin compositions, a suitable photoinitiator system has a direct impact on photosensitivity, resolution, and production yield.

[0004] Anthracene photosensitizers generally have good resolution and solubility, and therefore have received widespread attention in the industry. Currently, the most commercially available anthracene photosensitizer is primarily 9,10-dibutoxyanthracene (DBA). Typically, to achieve higher photosensitivity and resolution, these photosensitizers are used in conjunction with 2,4,5-triarylimidazole dimers (HABIs). However, these photosensitizer / photoinitiator combinations often face the following issues: The triggered fragments are prone to migration within the dry film, penetrating the polyethylene (PE) protective film surface to form crystals, which can cause defects such as short circuits and disconnections in the resist pattern, or risk a decrease in photosensitivity due to the photosensitizer penetrating the photosensitive layer. Summary of the Invention

[0005] This invention addresses the shortcomings of existing anthracene-based photosensitizers in photosensitive resin compositions, such as migration and crystallization and insufficient adhesion. By developing a novel anthracene-based photosensitizer and a high-performance photosensitive resin composition containing this photosensitizer, this design simultaneously achieves low mobility, high quantum yield, and excellent adhesion, meeting the demands of high-density circuit manufacturing.

[0006] The present invention discovered that upon exposure, the CO bond at the 9,10 position of the 9,10-dialkoxyanthracene photosensitizer breaks, dimerizing the anthracene ring and releasing small molecule alkoxy fragments. These small molecule fragments migrate from the cured photosensitive resin composition to the electroplating solution during the subsequent electroplating process, causing contamination and affecting the life of the plating solution and the electroplating effect.

[0007] Based on the above findings, the present invention proposes an anthracenemethyl-modified melamine photosensitizer for specific photosensitivity systems. This structure has the following technical advantages:

[0008] 1. Inhibit migration crystallization:

[0009] The anthracene group is flexibly connected through the methyl group, avoiding the breakage of carbon hetero bonds caused by p-π conjugation caused by direct bonding, thereby effectively suppressing the generation of small molecule fragments;

[0010] The rigid skeleton of melamine increases the molecular volume, hinders the migration and penetration of photosensitizer molecules, and reduces the risk of diffusion into the PE film.

[0011] 2. High quantum yield:

[0012] The introduction of multiple photosensitive anthracene ring photosensitive units and the melamine skeleton promote the stable transmission of photogenerated free radicals and improve curing;

[0013] 3. Solubility and development compatibility:

[0014] The dispersibility in the resin monomer / solvent can be adjusted by changing the substituent;

[0015] The molecular polarity is moderate, and it is not easy to aggregate in weak alkaline solution during development, reducing residue pollution.

[0016] (1) Photosensitive resin composition

[0017] A first aspect of the present invention provides a photosensitive resin composition, which comprises the following components based on 100 parts by mass of the photosensitive resin composition:

[0018] 50-65 parts of alkali-soluble resin A;

[0019] 35-50 parts of a photopolymerizable monomer B selected from ethylenically unsaturated carboxylic acids and / or ethylenically unsaturated carboxylic acid esters;

[0020] 2-5 parts of a photoinitiator C selected from a bisimidazole compound; and

[0021] 0.1-1 part of photosensitizer D, wherein the photosensitizer is anthracenemethyl-modified melamine having the structure of formula (I):

[0022] (I)

[0023] Wherein, R is selected from one of hydrogen, C1-C12 alkyl, C3-C12 cycloalkyl, C2-C12 unsaturated hydrocarbon, C6-C12 aryl, C6-C12 aryl substituted by one or more C1-C6 alkyl, and C6-C12 aryl substituted by one or more C1-C6 alkoxy;

[0024] R', R1, R2, R3 and R4 are each independently selected from one of hydrogen, C1-C12 alkyl, C3-C12 cycloalkyl, C2-C12 unsaturated hydrocarbon group, C1-C12 alkoxy, C6-C12 aryl or aryloxy, C6-C12 aryl or aryloxy substituted by one or more C1-C6 alkyl, C6-C12 aryl or aryloxy substituted by one or more C1-C6 alkoxy, halogen, cyano and nitro.

[0025] The photosensitive resin composition is photocured through the following photoinduced free radical polymerization reaction mechanism: the anthracenemethyl-modified melamine is excited by visible light to generate anthracene radicals, which trigger the homolysis of the bisimidazole compound to generate imidazole radicals, and the imidazole radicals activate the ethylenically unsaturated carboxylic acid and / or ethylenically unsaturated carboxylic acid ester to cause cross-linking and curing.

[0026] Wherein, the halogen is selected from fluorine, chlorine, bromine, and iodine, and is preferably chlorine.

[0027] Specifically, the photocuring process follows the mechanism of photoinduced free radical polymerization reaction: the first step is that the anthracenemethyl-modified melamine as a photosensitizer is excited to produce anthracene free radicals after absorbing photons; the second step is that the anthracene free radicals cause the bisimidazole compound as a photoinitiator to homolytically split, generating imidazole free radicals; the third step is the curing stage: the imidazole free radicals react with the ethylenically unsaturated carboxylic acid and / or ethylenically unsaturated carboxylic acid ester to open the unsaturated bonds of the activated monomer, causing a cross-linking reaction to form a 3D network structure, allowing the material to be rapidly cured and hardened.

[0028] Alkali soluble resin A

[0029] In the photosensitive resin composition provided by the present invention, wherein the alkali-soluble resin is an acrylate copolymer containing aromatic groups, from the perspective of improving product resolution and chemical resistance, the copolymerization ratio of the comonomer containing aromatic groups is preferably 50-70% based on the total weight of the comonomers during the copolymerization process.

[0030] In some embodiments of the present invention, the alkali-soluble resin is obtained by copolymerizing one or more of (meth)acrylic acid, alkyl (meth)acrylate, benzyl (meth)acrylate, benzyl (meth)acrylate derivatives, phenyl (meth)acrylate, styrene, and styrene derivatives. In some embodiments of the present invention, the alkali-soluble resin is copolymerized with (meth)acrylic acid and copolymerization units, and the copolymerization units are selected from one or more of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, hydroxyethyl (meth)acrylate, and styrene. In some specific embodiments of the present invention, the comonomers of the alkali-soluble resin include methacrylic acid, methyl methacrylate, hydroxyethyl methacrylate, benzyl methacrylate, and styrene.

[0031] Furthermore, the weight average molecular weight of the alkali-soluble resin is 20,000-60,000, the resin acid value is 160-220 mg KOH / g, and the molecular weight distribution index is 1.0-3.0. In an embodiment of the present invention, the content of the alkali-soluble resin is 50-65 parts by mass, preferably 55-60 parts by mass. If the content is less than 50 parts by mass, there is a tendency for the resist laminar flow glue to form, and if the content exceeds 65 parts by mass, there is a tendency for the resolution to decrease.

[0032] Photopolymerizable monomer B

[0033] According to the photosensitive resin composition provided by the present invention, the photopolymerizable monomer is a monomer having an ethylenically unsaturated double bond, preferably selected from (meth)acrylate monomers. In a preferred embodiment of the present invention, the photopolymerizable monomer is selected from one or more of methoxy polyethylene glycol monoacrylate, ethoxy (propoxy) nonylphenol acrylate, ethoxy (propoxy) bisphenol A di(meth)acrylate, ethoxy (propoxy) di(meth)acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, ethoxy (propoxy) trimethylolpropane tri(meth)acrylate, di(trimethylolpropane) tetraacrylate, ethoxy (propoxy) pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

[0034] In an embodiment of the present invention, the content of the photopolymerizable monomer is 35-50 parts by mass, preferably 40-50 parts by mass, and more preferably 45-50 parts by mass. If the content is less than 35 parts by mass, the sensitivity and chemical resistance of the resist tend to be reduced. If the content exceeds 50 parts by mass, the photosensitive resin composition is difficult to form into a thin film, and the resist tends to have laminar flow.

[0035] Photoinitiator C

[0036] According to the photosensitive resin composition provided by the present invention, the photoinitiator is a bisimidazole compound, such as a 2,4,5-triaryl imidazole dimer. Typical bisimidazole compounds, such as hexaaryl bisimidazole (HABI), are representative bisimidazole photoinitiators with a maximum absorption peak between 255 and 275 nm and are insensitive to long-wave ultraviolet light (e.g., 365 nm) and visible light. Another example is 2-(2-hydroxyphenyl)benzimidazole, which absorbs at 320 to 380 nm and is compatible with UV-A light sources (e.g., 365 nm LEDs), but is insensitive to visible light at 405 nm. The present invention successfully adjusts the operating wavelength of bisimidazole photoinitiators to approximately 405 nm by using an aminomethylanthracene photosensitizer that is excited under 405 nm illumination.

[0037] In a preferred embodiment of the present invention, the photoinitiator is selected from one or more of 2-(2-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(2-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, 2-(2-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(2-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(4-methoxyphenyl)-4,5-diphenylimidazole dimer, and 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4',5'-diphenyl-1,1'-diimidazole.

[0038] In an embodiment of the present invention, the content of the photoinitiator is 2-5 parts by mass, preferably 2-4 parts by mass, and more preferably 2.5-3.5 parts by mass. If the content is less than 2 parts by mass, the sensitivity and resolution of the resist tend to decrease, and if the content exceeds 5 parts by mass, the amount of development waste tends to increase.

[0039] Photosensitizer D

[0040] The photosensitive resin composition provided by the present invention comprises a melamine derivative modified with three anthracene 9-methyl groups as its photosensitizer. The rigid structure of the melamine skeleton and the methylene bridge (-CH2-An) design of the anthracene group provide significant advantages over traditional 9,10-dialkoxyanthracene photosensitizers. The methylene bridge structure avoids the breakage of the carbon-oxygen bond on the alkoxy group due to p-π conjugation, thereby reducing the migration of small molecule fragments after initiation, effectively inhibiting crystallization through penetration into the polyethylene protective film, and significantly reducing the risk of circuit short circuits. The introduction of multiple photosensitive units can greatly improve the photon yield. The use of the melamine skeleton can effectively improve the adhesion of the initiation system to the metal foil surface. In addition, the photosensitizer exhibits excellent solubility and formulation compatibility, and can be widely used in photocuring fields such as dry films, paints, coatings, inks, and molding materials.

[0041] In a preferred embodiment of the present invention, the anthracenemethyl-modified melamine photosensitizer is selected from one or more of the following compounds TM1-TM3:

[0042]

[0043] The anthracenemethyl-modified melamine photosensitizer described in the present invention can be synthesized by first condensing and dehydrating the amino group of melamine with the aldehyde group of 9-anthracenecarboxaldehyde to form an imine (-N=CH-An) intermediate, and then in situ reducing the C=N double bond of the imine with sodium borohydride (NaBH4) to form a stable aminomethyl bridge structure (-NH-CH2-An).

[0044] In some specific embodiments of the present invention, the synthesis mechanism of the anthracenemethyl-modified melamine photosensitizer comprises two-step transformation:

[0045] Condensation stage: The amino group (-NH2) of melamine and the aldehyde group (-CHO) of 9-anthracenecarboxaldehyde are refluxed and dehydrated at about 70°C in a tetrahydrofuran / methanol mixed solvent to form an imine (-N=CH-An) intermediate. Methanol, as a protic solvent, promotes the rightward shift of the reaction equilibrium.

[0046] Reduction stage: Sodium borohydride (NaBH4) is added under ice bath conditions to selectively reduce the C=N double bond of the imine intermediate, and a stable secondary amine structure (-NH-CH2-An) is generated through nucleophilic addition of hydrogen anions, which constructs a bridge between the anthracene methyl group and the nitrogen atom of melamine.

[0047] Other additives E

[0048] In various embodiments of the present invention, the photosensitive resin composition may further comprise one or more additives selected from dyes, photochromic agents, plasticizers, adhesion promoters, polymerization inhibitors, defoaming agents, and coating aids, as needed. Preferably, the total amount of the additives is 0.5-5.0 parts by weight.

[0049] (2) Photosensitive dry film

[0050] The second aspect of the present invention provides a photosensitive dry film, which includes, from bottom to top: a support layer; a photosensitive resist layer attached to the surface of the support layer; and a protective layer attached to the surface of the photosensitive resist layer, wherein the photosensitive resist layer is formed using the photosensitive resin composition provided by the first aspect of the present invention.

[0051] In some preferred embodiments of the present invention, the photosensitive dry film comprises from bottom to top: a PET support layer, a photosensitive resist layer formed by coating and drying the photosensitive resin composition provided by the first aspect of the present invention on the surface of the PET support layer, and a PE protective layer.

[0052] (3) Application of photosensitive dry film

[0053] A third aspect of the present invention provides applications of the above-mentioned photosensitive dry film in printed circuit boards, lead frames, semiconductor package substrates, solar cells, and photocurable inks.

[0054] The present invention integrates anthracene methyl photoactive groups into the melamine skeleton, breaking through the performance bottleneck of traditional anthracene photosensitizers. Its technical innovations mainly include:

[0055] Molecular design: rigid skeleton + flexible linker inhibits migration, and substituents can be adjusted to optimize solubility;

[0056] Photochemical performance: balance electron cloud density to achieve high quantum yield and low exposure energy consumption;

[0057] Industrial value: Raw materials are readily available, and the process is compatible with existing dry film production lines, significantly improving the yield of high-density circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which:

[0059] Figure 1 is the TM-1 photosensitizer of Example 1 of the present invention 1 H-NMR spectrum;

[0060] Figure 2 is the TM-1 photosensitizer of Example 1 of the present invention 13 C-NMR spectrum;

[0061] Figure 3 is the TM-2 photosensitizer of Example 2 of the present invention 1 H-NMR spectrum;

[0062] Figure 4 is the TM-2 photosensitizer of Example 2 of the present invention 13 C-NMR spectrum;

[0063] Figure 5 is the TM-3 photosensitizer of Example 3 of the present invention 1 H-NMR spectrum;

[0064] Figure 6 is the TM-3 photosensitizer of Example 3 of the present invention 13 C-NMR spectrum;

[0065] Figure 7 is the UV-Vis spectrum of the TM-1 photosensitizer of Example 1 of the present invention;

[0066] Figure 8 is a photobleaching curve of the TM-1 photosensitizer of Example 1 of the present invention;

[0067] Figure 9 is the UV-Vis spectrum of the TM-2 photosensitizer of Example 2 of the present invention;

[0068] Figure 10 is a photobleaching curve of the TM-2 photosensitizer of Example 2 of the present invention;

[0069] Figure 11 is the UV-Vis spectrum of the TM-3 photosensitizer of Example 3 of the present invention;

[0070] Figure 12 is a photobleaching curve of the TM-3 photosensitizer of Example 3 of the present invention;

[0071] Figure 13 This is the electron spin resonance (ESR) spectrum of TM-1 photosensitizer. DETAILED DESCRIPTION

[0072] The present invention will be further described in detail below in conjunction with specific embodiments. The examples given are only for illustrating the present invention, not for limiting the scope of the present invention.

[0073] Example 1: Preparation of photosensitizer TM-1

[0074]

[0075] In a nitrogen atmosphere, melamine (1 mmol) and 9-anthracenecarboxaldehyde (4 mmol) were added to a 50 mL three-necked flask equipped with a magnetic stirrer under stirring. Dry tetrahydrofuran (THF, 5 mL, concentration approximately 5 ml / mmol) and methanol (5 mL, concentration approximately 5 ml / mmol) were then added. The temperature was slowly raised to 70°C and refluxed for 10 h.

[0076] The mixture was cooled to room temperature, and sodium borohydride (25 mmol) was added under ice bath. The reaction was continued at room temperature (rt) for 8 h until the reaction of the raw material was basically complete as monitored by thin layer chromatography.

[0077] The solvent was removed under vacuum, and the obtained crude product was dissolved in a small amount of water, neutralized with dilute hydrochloric acid until neutral, and then filtered. The product was separated and purified by chromatography column using silica gel as the stationary phase to obtain photosensitizer TM-1 with a yield of about 90%.

[0078] 1 H NMR (400 MHz, d 6-DMSO): δ 8.56 (s, 3H), 8.48 (d, J = 8.83 Hz, 6H), 8.08 (d, J = 8.33 Hz, 6H), 7.60 – 7.50 (m, 12H), 5.47 (d, J = 5.11 Hz, 6H), 5.36 (t, J = 5.25 Hz, 3H) (ppm).

[0079] 13 C NMR (100 MHz, d 6 -DMSO): δ 133.0, 131.1, 129.8, 128.7, 127.1,125.8, 125.1, 124.8, 55.4 (ppm).

[0080] Example 2: Preparation of photosensitizer TM-2

[0081]

[0082] In a nitrogen atmosphere, melamine (0.5 mmol) and 10-methoxy-9-anthracenecarboxaldehyde (1.5 mmol) were added to a 50 mL three-necked flask equipped with a magnetic stirrer under stirring. Dry tetrahydrofuran (THF, 3 mL, concentration approximately 6 ml / mmol) and methanol (3 mL, concentration approximately 6 ml / mmol) were then added. The temperature was slowly raised to 70°C and refluxed for 10 h.

[0083] The mixture was cooled to room temperature, and sodium borohydride (12.5 mmol) was added under ice bath. The mixture was allowed to return to room temperature and react for 8 h until the reaction of the raw material was basically complete as monitored by thin layer chromatography.

[0084] The solvent was removed under vacuum, and the obtained crude product was dissolved in a small amount of water, neutralized with dilute hydrochloric acid until neutral, and then filtered. The product was separated and purified by chromatography using silica gel as the stationary phase to obtain photosensitizer TM-1 with a yield of about 80%.

[0085] 1 H NMR (400 MHz, (CD3)2CO): δ 8.52 (d, J = 7.40 Hz, 6H), 8.34 (d, J =7.50 Hz, 6H), 7.59 – 7.51 (m, 12H), 5.6 (s, 6H), 4.1 (s, 9H).

[0086] 13C NMR (100 MHz, (CD3)2CO): δ 152.6, 131.2, 128.9, 125.9, 125.2,124.9, 124.3, 122.4, 62.6, 55.9.

[0087] Example 3: Preparation of photosensitizer TM-3

[0088]

[0089] In a nitrogen atmosphere, melamine (0.6 mmol) and 10-methoxy-9-acetylanthracene (1.8 mmol) were added to a 50 mL three-necked flask equipped with a magnetic stirrer under stirring. Dry tetrahydrofuran (3 mL, concentration approximately 6 ml / mmol) and methanol (3 mL, concentration approximately 6 ml / mmol) were then added. The temperature was slowly raised to 70°C and refluxed for 10 h.

[0090] The mixture was cooled to room temperature, and sodium borohydride (15 mmol) was added under ice bath. The mixture was allowed to react at room temperature for 8 h until the reaction of the raw material was basically complete as monitored by thin layer chromatography.

[0091] The solvent was removed under vacuum, and the obtained crude product was dissolved in a small amount of water, neutralized with dilute hydrochloric acid until neutral, and then filtered. The product was separated and purified by chromatography column using silica gel as the stationary phase to obtain photosensitizer TM-3 with a yield of about 88%.

[0092] 1 H NMR (400 MHz, (CD3)2SO): δ 8.82 (d, J = 8.50 Hz, 6H), 8.29 (d, J =10.17 Hz, 6H), 7.55 – 7.50 (m, 12H), 6.30 (q, J = 6.82 Hz, 3H), 5.7 (s, 3H), 4.0 (s, 9H), 1.74 (d, J = 6.71 Hz, 9H).

[0093] 13 C NMR (100 MHz, (CD3)2SO): δ 151.8, 134.4, 129.5, 126.3, 125.6,125.4, 124.3, 122.8, 65.3, 63.4.

[0094] Figure 1 、 3 , 5 are photosensitizers TM-1-TM-3 1 H-NMR spectrum, Figure 2 、 4, 6 are photosensitizers TM-1-TM-3 13 C-NMR spectrum.

[0095] Example 4: Ultraviolet-visible absorption spectrum (UV-vis) measurement and photobleaching experiment

[0096] Ultraviolet-visible absorption spectra (UV-vis) were measured on a Shimadzu UV-1900 spectrophotometer using toluene as the solvent at a concentration of 2 × 10 -5 mol / L.

[0097] According to Lambert-Beer law, the molar extinction coefficient is ε=A bn / c, where A bn is the absorbance of the UV-visible absorption spectrum, and c is the concentration.

[0098] Photobleaching experiment: Using toluene as the solvent, the UV-visible absorption spectrum of the sample solution was measured using a Shimadzu UV-1900 UV-visible spectrophotometer under a 450 nm LED.

[0099] Figure 7 、 Figure 9 and Figure 11 The UV absorption spectra of TM-1, TM-2, and TM-3 are shown in Table 1. The molar extinction coefficients of photosensitizers TM-1-TM-3 and DBA are shown in Table 1.

[0100]

[0101] From the comparison of the UV absorption spectra in Table 1, it can be seen that the photosensitizers of the present invention generally have higher molar extinction coefficients than DBA, and some even have a higher molar extinction coefficient of more than 200%.

[0102] Figure 8 、 Figure 10 and Figure 12 They are the photobleaching spectra of TM-1, TM-2 and TM-3 respectively. It can be seen that the photosensitizer of the present invention has very good photobleaching performance, wherein the photobleaching time of TM1 is 60 minutes, the photobleaching time of TM2 is 30 minutes, and the photobleaching time of TM3 is 60 minutes.

[0103] Example 5: Electron Spin Resonance (ESR) Characterization

[0104] ESR-ST experiments were performed on a Bruker BioSpin ESR5000 electron spin resonance spectrometer with a field strength of 0-650 mT, a power of 9.5 GHz, and a frequency modulation of 100 kHz. An anthracene photosensitizer (0.01 mmol), BCIM (0.01 mmol), and a radical scavenger, methylpyridine N-oxide (DMPO, 0.02 mmol), were sequentially dissolved in THF (1.0 mL) under stirring. Irradiation was performed using a handheld 405 nm LED lamp for 1-3 minutes. A 25 μL sample was placed in an EPR test tube, purged with nitrogen to remove oxygen, and then placed in a test cell.

[0105] Figure 13 This is the EPR spectrum of TM-1. The spectrum shows the change of EPR signal with magnetic field strength (in Gauss G). The peak appears because the unpaired electrons split their energy levels in the magnetic field and absorb microwaves of a specific frequency to generate transition signals. The hyperfine coupling constant a is N = 13.2G.

[0106] Table 2 shows the quantitative data of the characteristic peaks in the spectrum (peak position, distance between adjacent peaks).

[0107] Average separation: ~15.12 G (highly consistent splitting constant).

[0108] Number of peaks: 3 peaks.

[0109] Peak intensity ratio: alternately 2:2:2.

[0110] Depend on Figure 13 As can be seen from Table 2, the anthracene photosensitizer of the present invention generates free radicals under 405 nm light conditions, which trigger the homolytic cleavage of the bisimidazole initiator to generate free radicals, which are captured by DMPO. This also indicates that the feasibility of developing photocurable compositions based on this type of initiation system is very high.

[0111] Example 6: Preparation of photosensitive resin composition

[0112] According to the formulation shown in Table 3, the components were mixed uniformly to prepare a photosensitive resin composition.

[0113]

[0114] Note: The weights in Table 3 are all calculated based on solid weight and do not include solvent components.

[0115] The components of each component code in Table 3 are described as follows:

[0116] Alkali-soluble resin A: Acrylate copolymer, solution polymerization, methacrylic acid / butyl methacrylate / benzyl methacrylate = 25 / 10 / 65 by mass; solvent: acetone. Solids content: 46%, weight-average molecular weight: 40,000, dispersity: 2.1, acid value: 163 mgKOH / g. (Hunan Chuyuan New Materials Co., Ltd.)

[0117] Photopolymerizable monomer B consisted of the following ingredients (purchased from Sartomer Guangzhou Chemical Co., Ltd.): 5 g of methoxy polyethylene glycol (350) monoacrylate, 20 g of 10 (ethoxy) bisphenol A dimethacrylate, 5 g of 6 (propoxy) bisphenol A dimethacrylate, 10 g of 3 (ethoxy) trimethylolpropane triacrylate, 4 g of di (trimethylolpropane) tetraacrylate.

[0118] Photoinitiator C: 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-diimidazole (BCIM);

[0119] Photosensitizer D: TM-1, TM-2 and TM-3 were prepared from Examples 1-3 respectively; DBA is 9,10-dibutoxyanthracene; DPHA is 9,10-diphenylanthracene; DAcOA is 9,10-diacyloxyanthracene

[0120] Additive E consists of the following ingredients (purchased from Anaiji Chemical): 0.5 g of leuco crystal violet, 0.05 g of malachite green, 0.8 g of p-toluenesulfonamide, 0.03 g of 2,6-di-tert-butyl-4-methylphenol

[0121] Solvent: composed of the following ingredients: 8g acetone, 10g toluene, 5g methanol

[0122] Example 7: Preparation of photosensitive dry film

[0123] The photosensitive resin composition listed in Table 3 of Example 6 was used to prepare a photosensitive dry film, comprising the following steps:

[0124] The photosensitive composition slurry prepared according to Table 3 was coated on a 15 μm thick polyethylene terephthalate (PET) support film using an experimental device (model: AB4220, TQC, the Netherlands). The film was baked at 80°C for 10 min to remove the solvent. After baking, the thickness of the photosensitive layer was controlled to 30 μm. The film was then covered with a polyethylene film (PE) for protection to obtain a photosensitive dry film.

[0125] Example 8: Preparation of a substrate with a resist pattern

[0126] The photosensitive compositions of Example Samples 1-3 and Comparative Samples 1-3 shown in Table 3 were used to prepare substrates with resist patterns. The process was as follows:

[0127] (1) Photosensitive layer forming step: forming a photosensitive layer on a substrate using a photosensitive composition;

[0128] (2) an exposure step of irradiating a portion of the photosensitive layer with active light to photocuring the portion to form a cured product region;

[0129] (3) Development step: removing the portion of the photosensitive layer other than the cured product region from the substrate to form a resist pattern on the substrate.

[0130] The operating conditions of each step are described in detail below.

[0131] Photosensitive layer formation process: A copper-clad laminate laminated with a 35 μm thick rolled 1.2 mm thick copper foil was used. After surface conditioning and preheating to 80°C, the PE protective film of the photosensitive dry film obtained in each embodiment or comparative example was peeled off, and the above-mentioned photosensitive resin composition layer was laminated to the copper-clad laminate using a hot roller laminator (Zhisheng Technology Co., Ltd., CSL-M25E) at a roller temperature of 110°C, an air pressure of 0.35 MPa, and a lamination speed of 1.5 m / min to obtain a test substrate.

[0132] Exposure process: Exposure is performed using a direct-drawing exposure machine (Core Micro, main wavelength 405nm). A Stouffer 41-level stage exposure scale is used for sensitivity testing, and the number of exposure grids is controlled at 14-18 grids.

[0133] Development Process: After exposure, the PET support film is peeled off and an alkali developer (manufactured by Guangzhou Julong Printed Circuit Equipment Co., Ltd., a dry film developer) is used to spray a 1wt% Na2CO3 aqueous solution at 30°C for twice the minimum development time to dissolve and remove the unexposed portions of the photosensitive resin layer. After development, the substrate is rinsed with pure water for 1.5 times the development time, dehydrated with an air knife, and then dried with warm air to obtain a substrate with a cured film for evaluation. The minimum development time is the shortest time required to completely dissolve the unexposed portion of the photosensitive resin layer.

[0134] Evaluation Project

[0135] 1. Sensitivity evaluation

[0136] A Stouffer 41-step scale was placed on the above-mentioned film-attached test substrate for sensitivity testing. After the exposure process, the test substrate was left to stand for more than 20 minutes, then the PET film layer was peeled off and a 1.0wt% sodium carbonate aqueous solution was sprayed at 30°C to remove the unexposed resist layer. The development time was 2.0 times the minimum development time. After the above operation, a cured film obtained by curing the photosensitive resin composition was formed on the surface of the substrate. The exposure energy (mJ / cm) when the number of remaining segments of the scale obtained by curing the film was 16 2 ), the sensitivity of the photosensitive resin composition was evaluated, and the smaller the value, the better the sensitivity.

[0137] 2. Adhesion evaluation

[0138] On the above-described post-filming test substrate, exposure was performed using a photomask with a line / space width of n:400 (unit: μm) at an energy level that resulted in 16 remaining steps after development using a Stouffer 41-step scale. After development, the resist pattern was observed using an optical microscope, and adhesion (μm) was evaluated using the minimum line width resulting in a complete, cured resist line. A smaller value indicates better adhesion.

[0139] 3. Resolution Evaluation

[0140] On the above-described post-filming test substrate, using a photomask with a wiring pattern of n:n line / space width (unit: μm), exposure was performed at an energy level that resulted in 16 remaining steps after development using a Stouffer 41-step scale. After development, the resist pattern was observed using an optical microscope, and the minimum line width resulting in a complete cured resist line was used as the adhesion value to evaluate resolution (μm). A smaller value indicates better resolution.

[0141] 4. Resist migration evaluation

[0142] After preparing the three-layer photosensitive dry film, the UV absorption spectrum of the dry film was measured using a UV spectrophotometer to obtain the absorbance of the maximum absorption peak between 350 and 450 nm, A1. The dry film was then placed at 30°C for 72 hours, and the PE film layer was removed from the surface of the photosensitive dry film. The UV absorption spectra of the PET layer and the photoresist layer were measured using a UV spectrophotometer to obtain the absorbance of the maximum absorption peak between 350 and 450 nm, A2. If the sensitizer migrates to the surface of the PE layer, the absorbance of the maximum absorption peak between 350 and 450 nm of the PET layer and the photoresist layer will decrease. In other words, the absorbance of the sensitizer that has migrated to the PE layer is (A1-A2). The degree of photosensitizer migration is calculated as the migration ratio A = (A1-A2) / A1. A larger value indicates a greater amount of migration.

[0143] Judgment basis:

[0144] ○: mobility A<0.01;

[0145] ×: Mobility A>0.01.

[0146] The test results of evaluation items 1-4 are summarized in Table 4 below.

[0147]

[0148] The results in Table 4 show that, under conditions of equal mass concentration, the exposure energy and resolution of the photosensitive resin composition samples containing the photosensitizer of the present invention as the core are comparable to those of DBA and DPHA, and superior to those of DAcOA. However, they exhibit significant advantages in terms of adhesion and mobility on the copper foil surface, solving the problem of DBA and DAcPA migrating to the PE film during the curing process. Furthermore, the experimental data of Example Samples 4-7 show that as the amount of photosensitizer TM-3 added is adjusted (from 50% to 150% of the baseline amount in parallel experiments), the photosensitivity comparable to that of the baseline amount is maintained, while exhibiting excellent adhesion and low mobility. This demonstrates that the photosensitizer of the present invention has high photosensitivity efficiency and a wide process applicability window, demonstrating excellent formulation adaptability.

[0149] The above contents are only preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art may make various modifications and changes within the spirit and principles of the present invention. Any changes, equivalent substitutions or improvements within this scope shall be deemed to be covered by the scope of protection of the present invention.

Claims

1. A photosensitive resin composition, comprising the following components based on 100 parts by mass of the photosensitive resin composition: Alkali-soluble resin A, 50-65 parts; 35-50 parts of a photopolymerizable monomer B selected from ethylenically unsaturated carboxylic acids and / or ethylenically unsaturated carboxylic acid esters; 2-5 parts of a photoinitiator C selected from a bisimidazole compound; and Photosensitizer D, 0.1-1 parts, It is characterized in that The photosensitizer is anthracenemethyl-modified melamine having the structure of formula (I): （I） Wherein, R is selected from one of hydrogen, C1-C12 alkyl, C3-C12 cycloalkyl, C2-C12 unsaturated hydrocarbon, C6-C12 aryl, C6-C12 aryl substituted by one or more C1-C6 alkyl, and C6-C12 aryl substituted by one or more C1-C6 alkoxy; R', R1, R2, R3 and R4 are each independently selected from one of hydrogen, C1-C12 alkyl, C3-C12 cycloalkyl, C2-C12 unsaturated hydrocarbon group, C1-C12 alkoxy, C6-C12 aryl or aryloxy, C6-C12 aryl or aryloxy substituted by one or more C1-C6 alkyl, C6-C12 aryl or aryloxy substituted by one or more C1-C6 alkoxy, halogen, cyano and nitro; The photosensitive resin composition is photocured through the following photoinduced free radical polymerization reaction mechanism: the anthracenemethyl-modified melamine is excited by visible light to generate anthracene radicals, which trigger the homolysis of the bisimidazole compound to generate imidazole radicals, and the imidazole radicals activate the ethylenically unsaturated carboxylic acid and / or ethylenically unsaturated carboxylic acid ester to cause cross-linking and curing.

2. The photosensitive resin composition according to claim 1, wherein The photosensitizer is selected from one or more of the following compounds TM1-TM3: 。 3. The photosensitive resin composition according to claim 1, wherein The content of the photosensitizer is preferably 0.1-0.8 parts by mass, more preferably 0.2-0.5 parts by mass.

4. The photosensitive resin composition according to claim 1, wherein The alkali-soluble resin is an acrylate copolymer containing an aromatic group; Preferably, the copolymerization ratio of the comonomer having an aromatic group is 50-70% based on the total mass of the comonomers in the copolymerization process; Preferably, the alkali-soluble resin is copolymerized with (meth)acrylic acid and a copolymerization unit, wherein the copolymerization unit is selected from one or more of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, hydroxyethyl (meth)acrylate, and styrene; Preferably, the alkali-soluble resin has a weight average molecular weight of 20,000-60,000, a resin acid value of 160-220 mg KOH / g, and a molecular weight distribution index of 1.0-3.

0.

5. The photosensitive resin composition according to claim 1, wherein The photopolymerizable monomer is a (meth)acrylate monomer; Preferably, the photopolymerizable monomer is selected from one or more of methoxy polyethylene glycol monoacrylate, ethoxy (propoxy) nonylphenol acrylate, ethoxy (propoxy) bisphenol A di(meth)acrylate, ethoxy (propoxy) di(meth)acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, ethoxy (propoxy) trimethylolpropane tri(meth)acrylate, di(trimethylolpropane) tetraacrylate, ethoxy (propoxy) pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate; Preferably, the content of the photopolymerizable monomer is 40-50 parts by mass, more preferably 45-50 parts by mass.

6. The photosensitive resin composition according to claim 1, wherein The photoinitiator is a 2,4,5-triaryl imidazole dimer; Preferably, the photoinitiator is selected from one or more of 2-(2-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(2-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, 2-(2-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(2-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(4-methoxyphenyl)-4,5-diphenylimidazole dimer, and 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4',5'-diphenyl-1,1'-diimidazole; Preferably, the content of the photoinitiator is 2-4 parts by mass, more preferably 2.5-3.5 parts by mass.

7. The photosensitive resin composition according to claim 1, wherein The photosensitive resin composition further comprises one or more additives selected from dyes, photochromic agents, plasticizers, adhesion promoters, polymerization inhibitors, defoaming agents, and coating aids; Preferably, the total amount of the additives is 0.5-5.0 parts by mass.

8. A photosensitive dry film, comprising from bottom to top: Support layer; a photosensitive resist layer attached to the surface of the support layer; and a protective layer attached to the surface of the photoresist layer, It is characterized in that the photosensitive resist layer is formed by using the photosensitive resin composition according to any one of claims 1 to 7.

9. The photosensitive dry film according to claim 8, characterized in that: The support layer material is PET, and the protective layer material is PE.

10. Use of the photosensitive dry film according to claim 8 or 9 in printed circuit boards, lead frames, semiconductor package substrates, solar cells and photocurable inks.

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