Photosensitive resin composition containing acridine methylene quaternary ammonium salt photosensitizer and application thereof

Abstract

The invention provides a photosensitive resin composition containing an acridine methylene quaternary ammonium salt photosensitizer and application of the photosensitive resin composition, quaternary ammonium group substituted methylene is introduced to the ninth position of a structural main body acridine ring of the photosensitizer, and acid radical or halogen is adopted as equilibrium anion. According to the photosensitizer, a quaternary ammonium salt group is introduced to the 9 site of an acridine ring, so that the problems that a traditional 9-phenylacridine photosensitizer is poor in compatibility, prone to crystallization and precipitation, insufficient in water solubility, weak in antistatic performance and the like in a formula are effectively solved. The photosensitive resin composition disclosed by the invention shows excellent dispersion stability, high sensitivity and high resolution, and can be used for remarkably reducing precipitates in a developing process and reducing poor lamination caused by static accumulation. The photosensitive dry film prepared based on the composition is suitable for fine pattern manufacturing in the fields of dry films, paints, coatings, printing ink, forming materials and the like, and has high yield and production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of photosensitive resin technology, and more specifically, relates to a photosensitive resin composition containing acridine methylene quaternary ammonium salt photosensitizer and its application. Background Technology

[0002] Photosensitive resin compositions are widely used as key pattern transfer materials in the manufacture of printed circuit boards (PCBs), lead frames (LFs), and semiconductor packaging (IC) substrates. Typically, the photosensitive resin composition is coated onto the surface of a PET support film, and after drying, a protective layer, such as a polyethylene film (PE) protective layer, is tightly bonded to its surface to form a photosensitive dry film (or dry film resist). In the pattern transfer process, the dry film resist is first bonded to a copper substrate, and a mask with a specific pattern is used to cover the dry film resist for pattern exposure. Then, a weakly alkaline aqueous solution is used as a developer to remove unexposed areas, followed by etching or electroplating to form the pattern. Finally, a stripping solution is used to peel off the cured dry film, thus achieving pattern transfer.

[0003] In actual coating production and applications, photosensitive resin compositions need to be tightly bonded to the metal foil surface to achieve the desired flatness or pattern resolution. However, static electricity not only causes problems such as wrinkling and poor exposure during dry film lamination, but also affects subsequent processes such as development and electroplating, reducing yield and product quality. Solutions to these problems generally involve incorporating small-molecule antistatic agents such as surfactants, conductive fillers, and polymer compounds into the photosensitive adhesive during the formulation process, reducing the film surface resistance to 10 Ω·cm. 6 -10 10 Ω, thereby achieving an antistatic effect, or even using conductive ropes pressed on the surface of dry film PET to eliminate static electricity through the conductive ropes.

[0004] Furthermore, as electronic devices become increasingly miniaturized and denser, the requirements for circuit precision are constantly increasing. To meet the demands of fine circuit manufacturing, photosensitive resin compositions need to possess higher resolution. To improve resolution, appropriate sensitizers need to be added to the photosensitive resin composition. For photosensitive resin compositions, a suitable photoinitiation system has a direct impact on photosensitivity, resolution, and production yield.

[0005] Currently, acridine derivatives, represented by 9-phenylacridine (9-PA), are widely used as photosensitizers. Typically, these photosensitizers are combined with 2,4,5-triarylimidazolium dimers (HABI) to achieve higher resolution or yield. However, this invention has found that such photosensitizer / photoinitiator combinations generally face the following problems:

[0006] 1) Due to its large conjugated system and high molecular rigidity, 9-phenylacridine has poor compatibility in photosensitive compositions and is prone to crystal precipitation, leading to a decrease in yield.

[0007] 2) 9-Phenylacetidine is a fat-soluble organic small molecule compound that is not water-soluble. The direct consequence is that fat-soluble photosensitizers and their fragments are prone to accumulating in aqueous developing solutions during the development process, producing precipitates and debris that easily adhere to the copper plate surface, causing problems such as residual copper or short circuits, thus affecting product yield.

[0008] 3) Although 9-phenylacridine is a polar molecule, its molecular dipole moment is relatively small. Therefore, after forming a photosensitive resin composition, its volume resistivity is high and its charge dissipation ability is poor. The direct consequence is that static electricity is easily accumulated on the surface of the PET film, which in turn causes wrinkling, blistering and other phenomena, affecting the product yield.

[0009] Therefore, developing a novel photoinitiating system that combines good antistatic properties, fat solubility, and water solubility, and constructing high-performance photocurable resin compositions based on this system, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0010] Therefore, the purpose of this invention is to overcome the above-mentioned defects of the prior art and provide an acridine-based photosensitizer, photosensitive resin composition and its application, which have low electroplating pollution, high photoinitiation efficiency, simple process and low cost.

[0011] This invention achieves the above objectives by providing a photosensitive resin composition comprising an acridine methylene quaternary ammonium salt photosensitizer, a photosensitive resist comprising the photosensitive resin composition, a photosensitive dry film, and the application of the photosensitive dry film in printed circuit boards, lead frames, semiconductor packaging substrates, solar cells, and photocurable inks. The photosensitizer of this invention can improve the formulation compatibility of existing dry film products, enhance the antistatic properties of the photosensitive resin composition, and significantly reduce the generation of developing waste, thereby improving product yield.

[0012] The inventors of this invention, through extensive literature review and experimental research, discovered the following problems and proposed innovative improvement solutions:

[0013] Due to their unique structure, acridine compounds or acridine derivatives can absorb ultraviolet light with a wavelength of around 365 nm, thereby generating acridine free radicals. These free radicals can be rapidly transferred to the diimidazole initiator, causing homolytic cleavage of the diimidazole structure, thereby initiating the chain polymerization reaction of acrylate monomers, thus achieving photocuring of the resin composition.

[0014] However, this invention has found that resin compositions using acridine-based photosensitizers, particularly formulations with 9-phenylacridine as the core photosensitive composition, still face the following problems in actual production and use:

[0015] 1) Due to its large conjugated system and high molecular rigidity, 9-phenylacridine has poor compatibility in photosensitive compositions and is prone to crystal precipitation, leading to a decrease in yield.

[0016] 2) 9-Phenylacetidine is a fat-soluble organic small molecule compound that is not water-soluble. The direct consequence is that fat-soluble photosensitizers and their fragments are prone to accumulating in aqueous developing solutions during the development process, producing precipitates and debris that easily adhere to the copper plate surface, causing problems such as residual copper or short circuits, thus affecting product yield.

[0017] 3) Although 9-phenylacridine is a polar molecule, its molecular polarity is insufficient. Therefore, after forming a photosensitive resin composition, its dielectric constant is high, resulting in high volume resistivity and poor charge dissipation ability. The direct consequence is that static electricity is easily accumulated on the surface of the PET film, which in turn causes wrinkling, blistering and other phenomena, affecting the product yield.

[0018] Based on the above findings, this invention proposes an acridine methylene quaternary ammonium salt photosensitizer and a photosensitive resin composition adapted thereto, in order to improve the antistatic properties, formulation dispersion stability and water solubility of existing dry film products, which can greatly reduce the static accumulation of the photosensitive resin composition, reduce the generation of developing waste, and improve product yield.

[0019] (a) Photosensitive resin composition

[0020] A first aspect of the present invention provides a photosensitive resin composition, based on 100 parts by weight of the photosensitive resin composition, comprising the following components: alkali-soluble resin A: 50-65 parts; photopolymerizable monomer B: 35-50 parts, selected from monomers containing olefinic unsaturated double bonds; photoinitiator C: 2-5 parts, selected from diimidazole compounds; and photosensitizer D: 0.1-1 parts, wherein the photosensitizer D is an acridine-9-methylene quaternary ammonium salt having the structure shown in formula (I):

[0021]

[0022] Among them, R a R b R c Each is independently selected from hydrogen and C1-C12 alkyl groups;

[0023] R1, R2, R3, R4, R5, R6, R7, and R8 are each independently selected from hydrogen, halogen, C1-C12 alkyl, C1-C12 alkoxy, C6-C12 aryl, C6-C12 aryl substituted with one or more halogens, C6-C12 aryl substituted with one or more C1-C12 alkyls, C6-C12 aryl substituted with one or more C1-C12 alkoxys, C6-C12 aryloxy, C6-C12 aryloxy substituted with one or more halogens, C6-C12 aryloxy substituted with one or more C1-C12 alkyls, and C6-C12 aryloxy substituted with one or more C1-C12 alkoxys.

[0024] X is selected from one of the following: halogen, nitrate, acetate, sulfate, trifluoromethanesulfonate, fluoroborate, and fluoroantimonate.

[0025] Optionally, in equation (I) R in part a R b and R c Any two elements in the set form a 3-8 elemental ring with N in the set.

[0026] As used herein, the term "9-phenylacridine compound" refers to a compound with a 9-phenylacridine core structure, which is optionally substituted at various positions. For example, it may be substituted by one or more C1-C12 alkyl groups at one or more positions.

[0027] As used herein, the term "alkyl" includes saturated aliphatic hydrocarbons containing both straight and branched chains. In some embodiments, the alkyl group has 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. For example, the term "C1-C2 alkyl," and the alkyl portion of other groups mentioned herein (e.g., C1-C2 alkoxy), refers to a straight or branched group with 1 to 12 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, or n-hexyl).

[0028] As used herein, the term "aryl" can include all carbon monocyclic or fused-ring polycyclic aromatic groups having a conjugated π-electron system. Aryl groups have 6 or 12 carbon atoms in a ring (or multiple rings). Most commonly, aryl groups have 6 carbon atoms in a ring. For example, as used herein, the term "C6-C12 aryl" refers to an aromatic group containing 6 to 12 carbon atoms, such as phenyl or naphthyl.

[0029] As used herein, the term "aryloxy group" refers to all carbon monocyclic or fused-ring polycyclic aromatic groups having a conjugated π-electron system linked by oxygen atoms. The aryl moiety in an aryloxy group has 6 to 12 carbon atoms in the ring (or rings). Most commonly, the aryl moiety in an aryloxy group has 6 carbon atoms in the ring. For example, as used herein, the term "C6-C12 aryloxy group" refers to an aryloxy group with 6 to 12 carbon atoms in the aryl moiety, such as phenoxy (-OC6H5) or naphthoxy (-OC... 10 H7).

[0030] Alkali-soluble resin A

[0031] According to the photosensitive resin composition provided by the present invention, the alkali-soluble resin A is an acrylate copolymer containing aromatic groups. From the perspective of improving product resolution and chemical resistance, preferably, the copolymerization ratio of comonomers having aromatic groups is 50-70% based on the total mass of comonomers during the copolymerization process.

[0032] In some embodiments of the present invention, the alkali-soluble resin is obtained by copolymerization of one or more of (meth)acrylic acid, alkyl (meth)acrylate, benzyl (meth)acrylate, benzyl (meth)acrylate derivatives, phenyl (meth)acrylate, styrene, and styrene derivatives.

[0033] In some embodiments of the present invention, the alkali-soluble resin is copolymerized from (meth)acrylic acid and a copolymer unit 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.

[0034] 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.

[0035] Furthermore, the alkali-soluble resin has a weight-average molecular weight of 20,000-60,000, an acid value of 160-220 mg KOH / g, and a molecular weight distribution index of 1.0-3.0.

[0036] In embodiments of the present invention, the content of alkali-soluble resin is 50-65 parts by weight, preferably 55-60 parts by weight. If the content is less than 50 parts by weight, there is a tendency for the resist to flow laminarly; if the content exceeds 65 parts by weight, there is a tendency for the resolution to decrease.

[0037] Photopolymerizable monomer B

[0038] According to the photosensitive resin composition provided by the present invention, the photopolymerizable monomer B is selected from monomers containing olefinic unsaturated double bonds, preferably from olefinic unsaturated carboxylic acids and / or olefinic unsaturated carboxylic acid esters, and more preferably from (meth)acrylate monomers.

[0039] In a preferred embodiment of the present invention, the photopolymerizable monomer is selected from one or more of the following: 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.

[0040] In embodiments of the present invention, the content of the photopolymerizable monomer is 35-50 parts by weight, preferably 40-50 parts by weight, and more preferably 45-50 parts by weight. If the content is less than 35 parts by weight, there is a tendency for the sensitivity and chemical resistance of the photoresist to decrease; if the content exceeds 50 parts by weight, there is a tendency for the photosensitive resin composition to be difficult to form a thin film and for the photoresist to flow as a laminar adhesive.

[0041] Photoinitiator C

[0042] According to the photosensitive resin composition provided by the present invention, the diimidazole compound 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.

[0043] In embodiments of the present invention, the content of 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, there is a tendency for the sensitivity and resolution of the photoresist to decrease; if the content exceeds 5 parts by mass, there is a tendency for the amount of developing debris to increase.

[0044] Photosensitizer D

[0045] The photosensitive resin composition provided by the present invention, wherein the photosensitizer D is an acridine-9-methylene quaternary ammonium salt having the structure shown in formula (I):

[0046]

[0047] The substituents are as defined above.

[0048] According to some embodiments of the present invention, X is selected from halogens and nitrates, more preferably, X is selected from halogens.

[0049] According to some embodiments of the present invention, R1, R2, R3, R4, R5, R6, R7 and R8 in formula (I) are each independently selected from hydrogen, halogen, C1-C12 alkyl, more preferably, each independently is hydrogen.

[0050] As can be seen from the above structural formula, in the acridine-9-methylene quaternary ammonium salt of formula (I), a quaternary ammonium group-substituted methylene group is introduced at the 9-position of acridine, with the counter ion being a negative acid anion or halogen. Compared with existing anthracene photosensitizers, the introduction of the cation-anion pair ensures the water solubility of this structure; at the same time, the presence of the quaternary ammonium salt ion containing the alkyl group also ensures the lipophilicity of this ionic compound. In addition, compared with existing 9-phenylacridine photosensitizers, it is less prone to crystallization and can be widely used in photocuring fields such as dry films, paints, coatings, inks, and molding materials.

[0051] In a preferred embodiment of the present invention, the photosensitizer is acridine-9-methylenetrimethylammonium bromide (TM1). In some specific embodiments of the present invention, the photosensitizer may have one of the following structures:

[0052]

[0053] In embodiments of the present invention, the content of photosensitizer can be 0.1-1 parts by mass, preferably 0.1-0.8 parts by mass, and more preferably 0.2-0.5 parts by mass. If the content is less than 0.1 parts by mass, the sensitivity of the photoresist tends to decrease; if the content exceeds 1 part by mass, there is a tendency for the photoresist underlayer to be incompletely cured, resulting in the photoresist cross-sectional shape being an "inverted trapezoid" and the resolution deteriorating.

[0054] The preparation strategy of the acridine-9-methylene quaternary ammonium salt shown in formula (I) of this invention can be universally derived through the typical synthetic routes of the examples. Those skilled in the art, based on conventional principles of organic synthesis and the specific preparation steps for compound TM1 in the examples, can clearly understand the general preparation logic of the acridine-9-methylene sulfate quaternary ammonium salt photosensitizer. Those skilled in the art can derive the preparation methods of all acridine-9-methylene quaternary ammonium salt photosensitizers of formula (I) by substituting different anions.

[0055] In some embodiments of the present invention, the preparation method may include the following steps: under a nitrogen atmosphere, 9-bromomethylacridine is added to a round-bottom flask equipped with a magnetic stirrer, followed by the addition of a trisubstituted amine and methanol, and the mixture is heated to reflux and reacted for a certain period of time; after the reaction is completed by monitoring by TLC (thin-layer chromatography), a large amount of DCM (dichloromethane) is added to the reaction solution until the reaction solution becomes clear, and solid is precipitated after standing at room temperature for 24 hours. The product is then filtered to obtain a yellow solid.

[0056] Additive E

[0057] In various embodiments of the present invention, the photosensitive resin composition may, as needed, further comprise one or more additives selected from dyes, photodevelopers, plasticizers, adhesion promoters, polymerization inhibitors, defoamers, and coating aids.

[0058] Preferably, the total amount of the additive is 0.5-5.0 parts by weight.

[0059] (ii) Photosensitive dry film

[0060] A second aspect of the present invention also provides a photosensitive dry film comprising, 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 in the first aspect of the present invention.

[0061] 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 surface of the PET support layer with the photosensitive resin composition provided in the first aspect of the present invention, and a PE protective layer.

[0062] (III) Applications of photosensitive dry film

[0063] The third aspect of the present invention provides applications of the above-mentioned photosensitive dry film in printed circuit boards, lead frames, semiconductor packaging substrates, solar cells, and photocurable inks.

[0064] The present invention has the following beneficial effects:

[0065] This invention employs an acridine-9-methylene quaternary ammonium salt of formula (I) with a quaternary ammonium group substituted at the 9-position of the main acridine ring as a photosensitizer, which has significant advantages over existing 9-phenyl acridine photosensitizers:

[0066] (1) The photosensitizing acridine structure and the functionalized quaternary ammonium salt structure are linked by methylene groups, which greatly reduces the rigidity of the molecule. While ensuring photosensitivity, the lipophilicity of the entire molecule is greatly improved, that is, the dispersion stability of the formulation, and the problem of crystallization of 9-phenyl acridine is overcome.

[0067] (2) The introduction of quaternary ammonium salts not only ensures excellent lipophilicity, but also improves the water solubility of the entire molecule, effectively reducing the accumulation of developing waste during the later development or stripping process, extending the service life of developing solution and electroplating solution, and reducing production costs.

[0068] (3) The introduction of anion and cation pair structure greatly improves the conductivity of the entire photosensitive resin composition, thereby preventing static electricity from accumulating. This reduces all the harm caused by static electricity, such as bubbles, poor adhesion and other defects, and improves product yield.

[0069] In addition to the objectives, features and advantages described above, the present invention also has other potential technical advantages, providing a better solution for the development of related fields.

[0070] In summary, the photosensitive dry film provided by this invention has excellent antistatic properties, dispersion stability, and superior developability. Compared with photosensitive resin compositions containing 9-phenylacridine photosensitizer, it has higher photosensitivity, which is beneficial to improving the production efficiency of customers and meeting the needs of high-density and high-precision printed circuit boards. Furthermore, its excellent solubility in conventional organic solvents and excellent water solubility are extremely beneficial for the formulation development of photosensitive compositions, and it can be widely used in the field of photocuring such as dry films, paints, coatings, inks, and molding materials. Attached Figure Description

[0071] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0072] Figure 1 It is the photosensitizer TM1 prepared in Example 1 of this invention. 1 H NMR spectrum;

[0073] Figure 2 It is the photosensitizer TM1 prepared in Example 1 of this invention. 13 C NMR spectrum;

[0074] Figure 3 This is the ultraviolet absorption spectrum of photosensitizer TM1 prepared in Example 1 of this invention;

[0075] Figure 4 This is the ultraviolet absorption spectrum of the photosensitizer TM1 prepared in Example 1 of the present invention after different irradiation times under 365 nm light conditions. Detailed Implementation

[0076] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0077] Example 1: Preparation of acridine-9-methylenetrimethylammonium bromide (photosensitizer TM1)

[0078] Under a nitrogen atmosphere, 9-bromomethylacridine (2 mmol) was added to a round-bottom flask equipped with a magnetic stirrer, followed by trimethylamine (3 mmol) and methanol (4 mL). The mixture was heated to reflux and reacted for approximately 2 hours. After the reaction was completed by TLC (thin-layer chromatography), a large amount of DCM (dichloromethane) was added to the reaction solution until the solution became clear. After standing at room temperature for 24 hours, a solid precipitated out. The product was filtered to obtain a yellow solid with a yield of 88%.

[0079] The structural formula of the product acridine-9-methylenetrimethylammonium bromide (photosensitizer TM1) is as follows:

[0080] .

[0081] Figure 1 It is photosensitizer TM1 1 H NMR spectrum Figure 2 It is photosensitizer TM1 13 C10 NMR spectrum.

[0082] 1 H NMR (400 MHz, COD): δ 8.65 (d, J = 8.85 Hz, 2H), 8.14 (d, J = 8.73Hz, 2H), 7.90 (t, 2H), 7.80 (t, 2H), 5.77 (s, 2H), 3.23 (s, 9H).

[0083] 13 C NMR (100 MHz, CD3OD): δ 148.2, 130.4, 130.2, 129.4, 127.9, 126.8,124.4, 58.6, 53.5.

[0084] Ultraviolet-Vis absorption spectroscopy (UV-Vis) measurement and photobleaching experiment

[0085] Ultraviolet-visible absorption spectroscopy (UV-Vis) was measured on a Shimadzu UV-1900 UV-Vis spectrophotometer using methanol as solvent at a concentration of 4 × 10⁻⁶. -5 mol / L; the test solvent for 9-phenylacridine was toluene with a concentration of 4 × 10⁻⁶ mol / L. -5 mol / L.

[0086] According to Beer-Lambert law, the molar extinction coefficient is ε = A. bn / c, where A bnν is the absorbance of the UV-Vis absorption spectrum, and c is the concentration.

[0087] Figure 3 This is the ultraviolet absorption spectrum of photosensitizer TM1; Figure 4 The images show the UV absorption spectra of photosensitizer TM1 after different illumination times under 365 nm light conditions. The molar extinction coefficient of photosensitizer TM1 is shown in Table 1 below.

[0088]

[0089] A comparison of the UV absorption spectra in Table 1 shows that the photosensitizer of this invention has a higher molar extinction coefficient than 9-phenylacridine; simultaneously, through... Figure 3 UV absorption spectrum and Figure 4 The comparison of the photobleaching curves shows that the photosensitizer TM1 of the present invention has very good photobleaching performance, and photobleaching is completed within 60 minutes.

[0090] Solubility test

[0091] Using acetone, toluene, methanol, and water as solvents, and a mixture of 5g of methoxy polyethylene glycol (350) monoacrylate, 20g of 10(ethoxy)bisphenol A dimethacrylate, 5g of 6(propoxy)bisphenol A dimethacrylate, 10g of 3(ethoxy)trimethylolpropane triacrylate, and 4g of di(trimethylolpropane)tetraacrylate as monomers (referred to as "monomers" in the table), the photosensitizers TM1 and 9-phenylacridine from Example 1 were tested for their solubility in various solvents and compatibility with monomers. The solute was added to the solvent at a ratio of 0.1g solute / 1g solvent (10% w / w), and the solubility was recorded according to the following grading criteria. The test results are shown in Table 2.

[0092] Excellent (rapid dissolution): Under room temperature and stirring conditions, a clear, transparent and homogeneous solution can be formed within 1 minute;

[0093] Medium (slow dissolution): Under room temperature and stirring conditions, a clear, transparent and uniform solution can be formed in more than 5 minutes; or it cannot be completely dissolved at room temperature, but a clear, transparent and uniform solution can be formed when heated to 50-60℃, and there is no obvious turbidity after returning to room temperature.

[0094] Poor (partially soluble): It cannot be completely dissolved in more than 5 minutes under room temperature and stirring conditions; or it can be completely dissolved when heated to 50-60℃, but becomes obviously turbid after returning to room temperature.

[0095]

[0096] As can be seen from the data in Table 2, compared with the conventional photosensitizer 9-phenylacridine (9-PA) in the prior art, the photosensitizer TM1 of the present invention exhibits superior solubility in various commonly used organic solvents and good compatibility with monomers. More uniquely, TM1 also exhibits excellent solubility in water, which is very helpful for the formulation design of photocurable compositions.

[0097] Examples 2-4 and Comparative Examples 1-3: Preparation of Photosensitive Resin Compositions

[0098] Referring to the formulation shown in Table 3, mix all components evenly to prepare a photosensitive resin composition. To facilitate coating, acetone solvent can be added to adjust the viscosity to an appropriate level. A blank indicates no acetone was added.

[0099] Referring to the formulations shown in Table 3, the photosensitive resin compositions of the present invention in Examples 2-4 were prepared. Simultaneously, photosensitive resin compositions using existing photosensitizers in Comparative Examples 1-3 were prepared for comparison. Specifically, the components corresponding to the samples numbered 2-4 and 1-3 in Table 3 were mixed evenly to prepare the photosensitive resin compositions.

[0100]

[0101] The components represented by the codes in Table 3 are explained below:

[0102] A (Alkali-soluble resin): Acrylic ester copolymer, solution polymerization, with a mass ratio of methacrylic acid / butyl methacrylate / benzyl methacrylate = 25 / 10 / 65; solvent is acetone, solid content is 46%, weight average molecular weight is 40,000, dispersity is 2.1, and acid value is 163 mg KOH / g. (Hunan Chuyuan New Materials Co., Ltd.)

[0103] B (photopolymerizable monomer) is composed of the following components (purchased from Sartoma Guangzhou Chemical Co., Ltd.): 5g of methoxy polyethylene glycol (350) monoacrylate, 20g of 10 (ethoxy) bisphenol A dimethacrylate, 5g of 6 (propoxy) bisphenol A dimethacrylate, 10g of 3 (ethoxy) trimethylolpropane triacrylate, and 4g of di (trimethylolpropane) tetraacrylate;

[0104] C (photoinitiator): 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-diimidazole (BCIM) (purchased from Jiuding Chemical);

[0105] E (additive) consists of the following ingredients (purchased from Anaiji Chemical): 0.5g of leuco crystal violet, 0.05g of malachite green, 0.8g of p-toluenesulfonamide, and 0.03g of 2,6-di-tert-butyl-4-methylphenol.

[0106] The solvent consists of the following components: 8g acetone, 10g toluene, and 5g methanol.

[0107] Preparation of photosensitive dry film

[0108] The preparation of photosensitive dry films from the various photosensitive resin compositions listed in Table 3 includes the following steps:

[0109] Using a coating experiment device (model: AB4220, TQC, Netherlands), the photosensitive composition paste prepared according to Table 3 was coated onto a 15μm thick polyethylene terephthalate (PET) support film. The solvent was removed by baking at 80℃ for 10 minutes. After baking, the thickness of the photosensitive layer was controlled at 30μm. Then, a polyethylene film (PE) was covered for protection to obtain a photosensitive dry film.

[0110] Preparation of resist patterned substrates

[0111] Substrates with resist patterns were prepared using the photosensitive compositions of Examples 2-4 of the present invention as shown in Table 3 and the photosensitive compositions of Comparative Examples 1-3, as follows:

[0112] (1) Photosensitive layer formation process: A photosensitive layer is formed on a substrate using a photosensitive composition;

[0113] (2) Exposure process: Irradiate a portion of the above photosensitive layer with active light to photocur the above area to form a cured area;

[0114] (3) Development process: Remove the portion of the photosensitive layer other than the cured area from the substrate and form a resist pattern on the substrate.

[0115] The operating conditions for each process are explained in detail below.

[0116] Photosensitive layer formation process: Using a copper-clad laminate with a 35μm thick rolled 1.2mm thick copper foil, after surface adjustment and preheating to 80°C, while peeling off the PE protective film of the photosensitive dry film obtained from each embodiment or comparative example, the above-mentioned photosensitive resin composition is laminated onto 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 0.35MPa, and a lamination speed of 1.5m / min to obtain a test substrate.

[0117] Exposure process: Exposure is performed using a direct drawing exposure machine (Xinge Microelectronics, main wavelength 365nm), and the sensitivity is tested using a Stouffer 41-level step exposure scale, with the number of exposure frames controlled between 14 and 18.

[0118] Development Process: After exposure, the PET support film is peeled off. Using an alkaline developer (manufactured by Guangzhou Julong Printed Circuit Board Equipment Co., Ltd., a dry film developer), a 1wt% Na2CO3 aqueous solution at 30°C is sprayed 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 using 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 for complete dissolution of the unexposed photosensitive resin layer.

[0119] Evaluation Project

[0120] 1. Sensitivity Evaluation

[0121] On the above-mentioned film-coated test substrate, a Stouffer 41-level stepped exposure scale was placed for photosensitivity 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 1.0 wt% 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 substrate surface. The exposure energy (mJ / cm) when the number of residual segments of the stepped exposure scale obtained by the cured film was 16. 2 The photosensitivity of the photosensitive resin composition was evaluated, with a smaller value indicating better photosensitivity.

[0122] 2. Evaluation of Dispersion Stability

[0123] The prepared photosensitive dry film was stored in the dark at 25°C for 2 weeks. The surface of the photosensitive layer was observed under a microscope and graded as follows:

[0124] ■ Indicates a uniform surface of the photosensitive layer;

[0125] × indicates undissolved material precipitated on the surface of the photosensitive layer.

[0126] 3. Evaluation of antistatic properties

[0127] The antistatic properties and surface durability of the photosensitive resin composition coated on PET film were evaluated using a friction test method, as follows:

[0128] Take a cotton swab and thoroughly moisten it with anhydrous ethanol. Hold the moistened cotton swab at a constant angle of 45° to the film surface and rub a selected area on the PET film surface in a straight line for 5 cm with a vertical load of 1 N and a constant speed of 5 cm / s. Then immediately return to the original path and rub again. This round trip is recorded as completing one cycle (n=1).

[0129] Continuously perform the above cyclic friction until slight visible damage or wrinkling appears on the surface of the PET film for the first time. Record the number of cycles completed at this time, denoted as n.

[0130] Evaluation criteria: Evaluate the antistatic performance level based on the maximum tolerable number of cycles n:

[0131] Excellent: n ≥ 10 times;

[0132] Good: 4 < n < 10 times;

[0133] Fair: n ≤ 3 times.

[0134] 4. Development precipitate evaluation

[0135] To evaluate the dissolution stability and impurity precipitation tendency of the photosensitive resin composition in an alkaline developer, the following accelerated simulation and quantitative analysis methods are used:

[0136] Weigh 18.0 g of the sample from the dried photosensitive resin layer and completely dissolve it in 1 L of an aqueous Na2CO3 solution with a concentration of 1 wt% (simulating the developer). Transfer the above solution to a micro-developer and circulate and spray it for 60 minutes at a constant temperature of 30°C and a spraying pressure of 0.12 MPa to simulate the mechanical and dynamic effects during the actual development process.

[0137] After the cycle ends, take out the developer, let it stand at room temperature for 72 hours to allow the possible slightly soluble or suspended substances to fully settle. Filter the standing solution using ADVANTEC NO. 2 qualitative filter paper and collect all the solid residues. Dry the filter paper and the precipitate at an appropriate temperature to a constant weight and weigh the mass of the precipitate.

[0138] Result calculation and grading: Calculate the percentage of the precipitate mass to the initial sample mass (18.0 g), denoted as w. Conduct the following grading evaluation based on the w value:

[0139] ○ Indicates excellent: 0 ≤ w ≤ 0.6%,

[0140] △ Indicates acceptable: 0.6% < w ≤ 0.8%,

[0141] × Indicates unacceptable: 0.8% < w.

[0142] Summarize the test results of evaluation items 1 - 4 in Table 4 below.

[0143]

[0144] The results in Table 4 show that, compared with the photosensitive resin compositions of Comparative Examples 1-3, the photosensitive resin compositions prepared by using photosensitizer TM1 prepared in Example 1 in Examples 2-4 of this invention, within the addition range of 0.1-1.0, can maintain similar performance in terms of photosensitivity and resolution, while exhibiting significant advantages in performance such as dispersion stability, migration, and amount of developing debris; however, below 0.1, the performance decreases significantly; and above 1.0, as in Comparative Example 2, although the performance is improved, there is a risk of resin runoff and performance instability in actual production.

[0145] The above results demonstrate that the photosensitizer of the present invention has broad applicability, high photosensitivity and good formulation compatibility, and can greatly reduce development waste, exhibiting excellent formulation adaptability.

[0146] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art can make various modifications and alterations within the spirit and principles of the present invention, and any modifications, equivalent substitutions, or improvements within this scope should be considered as covered by the protection scope 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: an alkali-soluble resin A: 50 to 65 parts; a photopolymerization monomer B: 35 to 50 parts, which is selected from a monomer containing an ethylenically unsaturated double bond; a photoinitiator C: 2 to 5 parts, which is selected from a bis-imidazole compound; and a photosensitizer D: 0.1 to 1 part, the photosensitizer being an acridin-9-ylmethylene quaternary ammonium salt having a structure represented by formula (I): wherein R1, R2, R3, R4, R5, R6, R7, and R8 are each independently selected from hydrogen, halogen, C1-C12 alkyl, C1-C12 alkoxy, C6-C12 aryl, C6-C12 aryl substituted with one or more halogens, C6-C12 aryl substituted with one or more C1-C12 alkyl groups, C6-C12 aryl substituted with one or more C1-C12 alkoxy groups, C6-C12 aryloxy, C6-C12 aryloxy substituted with one or more halogens, C6-C12 aryloxy substituted with one or more C1-C12 alkyl groups, C6-C12 aryloxy substituted with one or more C1-C12 alkoxy groups; and X is selected from one of halogen, nitrate, acetate, sulfate, triflate, fluoroborate, and fluorantimonate; the compound of formula (I) having the following structure: the content of the photosensitizer D being 0.1 to 0.8 parts by mass. 2.The photosensitive resin composition according to claim 1, wherein the alkali-soluble resin A is an acrylate copolymer containing an aromatic group; and the copolymerization ratio of a comonomer having an aromatic group is 50 to 70% based on the total mass of the comonomers in the copolymerization process. 5.The photosensitive resin composition according to claim 1, wherein the weight average molecular weight of the alkali-soluble resin A is 20,000 to 60,000, the resin acid value is 160 to 220 mg KOH / g, and the molecular weight distribution index is 1.0 to 3.

0. 6.The photosensitive resin composition according to claim 1, wherein the photopolymerization monomer B is selected from one or more of methoxypolyethylene 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. 7.The photosensitive resin composition according to claim 1, wherein the bis-imidazole compound is selected from one or more of 2-(2-chlorophenyl)-4,5-diphenyl imidazole dimer, 2-(2-chlorophenyl)-4,5-di(methoxyphenyl) imidazole dimer, 2-(2-fluorophenyl)-4,5-diphenyl imidazole dimer, 2-(2-methoxyphenyl)-4,5-diphenyl imidazole dimer, 2-(4-methoxyphenyl)-4,5-diphenyl imidazole dimer, and 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4',5'-diphenyl-1,1'-biimidazole. wherein ​ wherein R a , R b , and R c are each independently selected from hydrogen and C1-C12 alkyl; ​ ​ Optionally, any two of R in the moiety a , R b and R c form a 3-8 membered ring with the N therein.

2. The photosensitive resin composition according to claim 1, wherein ​ 。 3. The photosensitive resin composition according to claim 1, wherein ​ 4. The photosensitive resin composition according to claim 1, wherein ​ ​ 6. The photosensitive resin composition according to claim 1, wherein ​ 7. The photosensitive resin composition according to claim 1, wherein ​ 8. The photosensitive resin composition according to claim 1, wherein The photosensitive resin composition further comprises one or more additives E selected from the group consisting of dyes, photo-developers, plasticizers, adhesion promoters, polymerization inhibitors, antifoaming agents, coating aids; the total amount of the additives E is 0.5-5.0 parts by mass.

9. A photosensitive dry film comprising, 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 according to any one of claims 1 to 8.

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

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