Photosensitive resin, preparation method of photosensitive resin and photosensitive dry film

Abstract

This invention proposes a photosensitive adhesive, a method for preparing the photosensitive adhesive, and a photosensitive dry film, comprising: designing the raw material components of the photosensitive adhesive; adding an acrylic monomer containing a tertiary amine structure during polymer synthesis, or adding an acrylic monomer containing a tertiary amine structure and / or an aminocarboxylic acid chelating agent to the adhesive, wherein the acrylic monomer containing the tertiary amine structure and the aminocarboxylic acid chelating agent account for 0.01 to 5.0 parts by mass of the total mass of the above components. The tertiary amine structure of this invention can capture free radicals, and the carbon-carbon double bonds in the acrylic groups can construct a stable molecular framework through copolymerization and crosslinking reactions, synergistically inhibiting the performance degradation of the adhesive. Simultaneously, the aminocarboxylic acid chelating agent adsorbs free metal ions, thereby improving the shelf life of the photosensitive adhesive and the photosensitive dry film.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a photosensitive adhesive, a method for preparing the photosensitive adhesive, and a photosensitive dry film. Background Technology

[0002] Photosensitive adhesives (or photoresists) are key materials in microelectronics manufacturing, printed circuit boards, precision molds, and holographic imaging. Their shelf life (or effective lifespan) refers to the time under specific conditions during which the adhesive maintains its key performance indicators (such as photosensitivity, viscosity, coating uniformity, and development characteristics) without significant degradation. Shelf life directly determines the stability of the adhesive's process window, batch consistency, and the yield of the final product, and is one of the core parameters for evaluating the practicality and commercial value of photosensitive adhesives.

[0003] However, photosensitive adhesives, especially high-performance formulations, face significant challenges in terms of storage stability. These adhesive systems typically contain resins, reactive diluents, photoinitiators, dyes, and various additives. Their complex multi-component nature means that their shelf life is influenced by both internal factors (chemical composition) and external factors (storage environment). Inherent chemical instability: Active components in the adhesive (such as acrylate monomers and free radical photoinitiators) may undergo slow thermally induced polymerization or side reactions during storage. In addition, long-term compatibility issues between photoinitiators and monomers and additives may also lead to component leaching or performance degradation.

[0004] Therefore, developing a novel formulation technology and preparation method that can significantly extend the shelf life of photosensitive adhesive while maintaining or even improving its photolithographic performance has important industrial application value.

[0005] In the prior art, there are also technical solutions for improving the hue stability of photosensitive resin compositions. For example, Chinese invention patent application number 202310095703.6 discloses a photosensitive resin composition and dry film resist laminate with improved system hue stability. Its core innovation lies in introducing piperidine compounds into the photosensitive resin composition to ensure that the hue change value Δb≤5, and the resist film layer has excellent resistance to pattern electroplating. Summary of the Invention

[0006] The purpose of this invention is to provide a photosensitive adhesive, a method for preparing the photosensitive adhesive, and a method for preparing a photosensitive dry film, which can improve the shelf life. This is achieved through the following technical means: A photosensitive adhesive, by weight, comprises the following raw materials: The composition includes 48-65 parts polymer, 36-50 parts monomer, 0.5-5 parts photoinitiator, 5-25 parts solvent, and 0.01-5.0 parts additives. The additives include a first additive and / or a second additive; The first additive is an acrylic monomer containing a tertiary amine, that is, a compound represented by general formula I: General Formula I The core structure of the first additive is: acryloyl group X + linker chain Y + tertiary amine group Z, including two forms: Format 1:

[0007] When X is an acrylate (CH2=CHCOO-), Y is an alkylene group (CH2). n - any one of hydroxyalkyl (-OHR-) or ester (-COOR-); R, R1, and R2 are any one of hydroxyl, alkyl with 1-12 carbon atoms, benzoyloxy, aromatic group, etc.; R3 is a hydrogen atom, alkyl, hydrocarbon group, etc.

[0008] Specifically: such as diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, dimethylaminopropyl methacrylate, morpholine ethyl methacrylate, morpholine ethyl acrylate, tert-butylaminoethyl methacrylate, etc. Form Two:

[0009] When X is acrylamide (CH2=CHCON-), Y is an alkylene group (CH2). n - hydroxyalkyl (-OHR-), ester (-COOR-); R, R1, and R2 are any one of alkyl, benzoyloxy, aromatic, etc., with 1-12 carbon atoms; R3 is a hydrogen atom, alkyl, hydrocarbon, etc.

[0010] Specifically: such as N-(3-dimethylaminopropyl)methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, and N,N-dimethylmethacrylamide.

[0011] The preferred additive for the first category is diethylaminoethyl methacrylate.

[0012] The second additive is a compound comprising the following general formula II: Formula II Where n is 1-3; representing the main structure; R, R1, R2, R3, R4, and R5 can each be present in 1 to 6 groups, representing carboxyl groups. Cycles, hydroxyl groups, phenolic groups, methyl groups, etc., can also be introduced to chemically modify the carboxyl groups.

[0013] Specifically, any one of the following: ethylenediaminetetraacetic acid (EDTA), tetramethylethylenediamine (TMEDA), diethylenetriaminepentaacetic acid (DTPA), hypozinotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), tetrasodium glutamate diacetate (GLDA), triethylenetetraaminehexaacetic acid (1,2-cyclohexanediaminetetraacetic acid), and hypozinotriacetic acid (NTA).

[0014] The preferred additive for the second category is ethylenediaminetetraacetic acid (EDTA).

[0015] A method for preparing a photosensitive adhesive or photosensitive dry film includes the following steps: Step 1: Add the first additive to 48-65 parts of polymer, mix evenly, and allow it to fully undergo a reflux reaction at 75-85℃ to produce thermal polymerization and complete the primary crosslinking. Then let it stand for 2 hours.

[0016] Step 2: Mix 36-50 parts of monomer, 0.5-5 parts of photoinitiator, and 5-25 parts of solvent, and stir to ensure thorough mixing to obtain the adhesive solution; The first additive is 0.01%-5% in parts: Step 3: Stir the adhesive and polymer at 65-80℃ to allow for dense cross-linking reaction, filter, and then allow it to fully undergo photopolymerization at 18-22℃ to obtain the photosensitive adhesive.

[0017] Step 4: Using a coating machine, coat the above photosensitive adhesive solution onto the surface of a 15μm thick PET support film. Bake at 80℃ for 10 minutes to obtain a photosensitive layer with a thickness of 15μm. Finally, cover the surface of the photosensitive layer with a PE film for protection, completing the preparation of the photosensitive dry film.

[0018] A method for preparing a photosensitive adhesive or photosensitive dry film includes the following steps: Step 1: Prepare 48-65 parts of polymer; Step 2: Mix 36-50 parts of monomer, 0.5-5 parts of photoinitiator, 5-25 parts of solvent, the first additive and / or the second additive, and stir to fully mix them to obtain the adhesive solution; The total amount of the first and second additives is 0.01%-5%. Step 3: Mix the adhesive and polymer evenly, stir at 75-85℃ for 2 hours to fully reflux and generate thermal polymerization, completing the primary crosslinking, and then let stand for 2 hours; stir at 65-80℃ for dense crosslinking reaction, filter, and then allow it to fully undergo photomonomer polymerization at 18-22℃ to obtain the photosensitive adhesive.

[0019] Step 4: Using a coating machine, coat the above photosensitive adhesive solution onto the surface of a 15μm thick PET support film. Bake at 80℃ for 10 minutes to obtain a photosensitive layer with a thickness of 15μm. Finally, cover the surface of the photosensitive layer with a PE film for protection, completing the preparation of the photosensitive dry film.

[0020] Compared with the prior art, the advantages of the present invention are: 1. A complex system composed of EDTA is added to the adhesive solution, exhibiting a synergistic effect in adsorbing metal ions, promoting cross-linking, and aiding in the initiation of photopolymerization. This differs from existing technologies using single piperidine compounds. EDTA is utilized to form a complex, adsorbing metal ions, such as... Figure 1 As shown. Specifically: The structure of EDTA forms positively charged ions through protonation, which then react with metal ions (such as Fe). 3+ Cu 2+ (etc.) form stable complexes (structure see...) Figure 1 This structure can "encapsulate" metal ions, preventing them from being released again and reducing their impact. Metal ions are a key factor leading to resin degradation and photosensitivity decline. Adsorption can significantly reduce their interference with the photopolymerization reaction and further extend the shelf life.

[0021] 2. Adding acrylic (amide) monomers containing tertiary amines (such as diethylaminoethyl methacrylate) to the resin system, at a proportion of approximately 0.01%–5%, can optimize the synthesis and performance of the material at multiple levels. These monomers primarily function through the following mechanisms: First, during polymerization, the acrylic organic groups of the monomer participate in and promote resin crosslinking, while simultaneously forming stable complexes with acidic components in the system, contributing to enhanced overall structural stability. The nitrogen atoms in the tertiary amine structure are rich in lone pair electrons, which can synergistically interact with free radicals generated by the decomposition of photoinitiators, thereby accelerating the copolymerization reaction between the monomer and polymer, promoting more complete polymerization, and fostering a more regular molecular chain arrangement. Second, in the cured resin system, the tertiary amine groups are stably embedded within the molecular chain through chemical bonds, reducing the exposure of active ends and inhibiting potential molecular chain degradation or abnormal crosslinking during storage. This helps maintain the stability of the resin's molecular weight distribution, avoiding excessively wide or fluctuating molecular weight distribution. Simultaneously, the polarity of the tertiary amine groups is well-matched with the acrylic resin, photopolymerizing monomers, and photoinitiators in the photosensitive adhesive, improving the compatibility and system homogeneity among the components. Finally, the tertiary amine structure also possesses a certain photosensitizing effect. In synergy with photoinitiators, it can appropriately reduce the exposure energy required for curing without compromising the storage and reaction stability of the system. This reduces the occurrence of adhesive layering, precipitation, or uneven local concentration during storage, ensuring uniform reaction during development and avoiding problems such as development residue and blurred pattern edges. It also improves the film quality and adhesion of the dry film. Furthermore, it prevents premature decomposition of photoinitiators, monomer oxidation, or polymer chain degradation in the photosensitive adhesive catalyzed by metal ions, thereby reducing color changes (such as yellowing or darkening), abnormal viscosity increases, and photosensitivity degradation (such as decreased sensitivity and reduced resolution) during adhesive storage.

[0022] Figure 2 The diagram shows the interaction between diethylaminoethyl methacrylate and resin.

[0023] The synergistic effect of the tertiary amine and acrylic acid double bond structures: A. Through the "tertiary amine-acrylic acid double bond structure," the nitrogen atom in the tertiary amine structure can form a "synergistic initiation system" with the photoinitiator. After the photoinitiator absorbs exposure energy, it generates free radicals, and the tertiary amine can accelerate the generation and transmission of free radicals, thereby increasing the photopolymerization reaction rate. The polar amine groups in the tertiary amine structure can increase the surface tension and viscosity of the resin, making the resin adhere more tightly to the PET film after coating, avoiding "delamination" problems during drying or laminating PE films. This improves the stability of the resin and extends its shelf life.

[0024] A1. Complexation and adsorption effect of tertiary amine structure: The tertiary amine structure of the compound system (such as diethylaminoethyl methacrylate) can promote resin cross-linking and form polymer with the resin, providing a "uniform reaction space" for photopolymerization reaction, avoiding rough edges of photolithographic patterns caused by uneven local curing of resin during photopolymerization; at the same time, it can fix the pattern shape after curing, reduce pattern deformation during development, and further ensure curing uniformity.

[0025] In summary, the improvement effect of the "tertiary amine-acrylic acid double bond structure" compound system is not a "simple superposition" of components, but rather a "multifunctional integrated improvement" achieved through the synergistic effect of "tertiary amine (complexing, co-initiating, anti-aging) and acrylic acid double bond structure (crosslinking, anti-photoaging, compatibilizing)". This is the core innovation point that distinguishes this invention from the prior art.

[0026] A gradient crosslinking process is employed to precisely control the resin structure, enhancing its anti-aging properties and stability. By controlling the crosslinking reaction in stages through a temperature gradient of "high temperature → medium temperature → low temperature," premature activation of the photoinitiator and loose resin structure are avoided, achieving precise temperature control and structural stability. Specifically, the temperature and time control logic is as follows: "primary crosslinking at 75-85℃ → dense crosslinking at 65-80℃ → photomonomer compounding at 18-22℃," and its effect on improving the long-term stability of the dry film. This differs from existing technologies that involve "direct drying after mixing."

[0027] The difference between tertiary amines and piperidine compounds: Mechanism: At 20-40℃, the piperidine ring is easily oxidized to imine or amide, losing its free radical scavenging ability. Long-term storage may lead to slow oxidation, resulting in a decrease in concentration and a decline in color stability. Tertiary amines, on the other hand, do not have α-H atoms on their nitrogen atom and are not easily oxidized. Their oxidation rate is only 1 / 5 to 1 / 10 that of piperidine, and they have better long-term stability. The NH bond of piperidine may react with the excited state of the photoinitiator, consuming the photoinitiator, reducing its efficiency, and leading to decreased photosensitivity (requiring higher exposure energy). Tertiary amines can act as co-initiators of photoinitiators, promoting the generation of free radicals without consuming themselves. Tertiary amines not only do not affect hue stability but can also improve photosensitivity.

[0028] Application environment: Low temperature: At low temperatures of 0-10℃, the solubility of piperidine compounds decreases (especially piperidines with high carbon chain substitution, such as dipiperidine sebacate), and they are prone to precipitation and crystallization, resulting in uneven color of the adhesive solution (white spots or color spots appear); while tertiary amine structures (such as triethylamine) have good water solubility, no risk of precipitation at low temperatures, and can maintain the uniformity of the adhesive solution. High humidity environment: In high humidity (e.g., RH≥80%), the NH bond of piperidine compounds easily combines with water molecules and undergoes hydrolysis (especially ester piperidines, such as dipiperidine sebacate), generating carboxylic acid and piperidinol, losing their free radical scavenging ability, resulting in an increase in hue Δb; tertiary amine structures (such as N,N-dimethylaniline) do not have NH bonds and do not undergo hydrolysis, exhibiting better hue stability under high humidity; PET and metal substrates: Tertiary amines generally improve the adhesion of resins to metal substrates. Piperidine mainly acts within the bulk phase, and its effect on improving interfacial adhesion is not as significant as that of tertiary amines; tertiary amines also affect color stability and adhesion on metal substrates (such as direct coating of copper foil). cost: The preparation of piperidine compounds (such as 1,2,2,6,6-pentamethyl-4-piperidinol) requires a multi-step cyclization reaction, and the cost is about 3 to 5 times that of tertiary amines (such as triethylamine). There are also certain risks in the supply chain, and the stability of large-scale industrial supply remains to be seen. Attached Figure Description

[0029] Figure 1 It is a complex formed by EDTA and metal ions; Figure 2 It is a reaction between diethylaminoethyl methacrylate and resin. Detailed Implementation

[0030] The photosensitive adhesive, its preparation method, and the photosensitive dry film of the present invention will be described in more detail below with reference to schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0031] The method for improving the shelf life of the photosensitive adhesive of the present invention will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0032] The polymer, or resin, has the following specific chemical composition: 22% methacrylic acid, 35% methyl methacrylate, 28% styrene, 10% butyl acrylate, and 5% isooctyl acrylate. The weight-average molecular weight is 55,000, and the molecular weight distribution index is 2.2. The alkali-soluble resin solids component is 38%, and the solvent is 47% acetone and 15% methanol.

[0033] The specific components of the adhesive are: UV-1 (21g), UV-2 (7g), UV-3 (6g), UV-4 (9g), PI-1 (3.7g), PI-2 (0.1g), PI-3 (0.5g), PI-4 (0.5g), D-1 (0.03g), ZJ-1 (0.02g), ZJ-2 (0.2g) and ZJ-3 (0.2g), Sol-1 (5g) and Sol-2 (10g).

[0034] The specific substances corresponding to each sample code are: UV-1 (Bisphenol A dimethacrylate ethoxylate, 10EO), UV-2 (Bisphenol A dimethacrylate ethoxylate, 30EO), UV-3 (Trimethylolpropane triacrylate ethoxylate, 9EO), UV-4 (Polyethylene glycol (600) diacrylate). PI-1 (2-(o-chlorophenyl)-4,5-diphenylimidazolium dimer), PI-2 (tribromomethylphenyl sulfone), PI-3 (Basic Blue), PI-4 (p-toluenesulfonamide); D-1 (Malachite Green), ZJ-1 (MEHQ p-methoxyphenol), ZJ-2 (leveling agent), ZJ-3 (defoamer), Sol-1 (methanol), Sol-2 (toluene).

[0035] Monomers include: UV-1 (bisphenol A dimethacrylate ester ethoxylate, 10EO), UV-2 (bisphenol A dimethacrylate ester ethoxylate, 30EO), UV-3 (trimethylolpropane triacrylate ethoxylate, 9EO), UV-4 (polyethylene glycol (600) diacrylate), and ZJ-1 (MEHQ p-methoxyphenol). Photoinitiators include: PI-1 (2-(o-chlorophenyl)-4,5-diphenylimidazolium dimer), PI-2 (tribromomethylphenyl sulfone), PI-3 (leuco crystal violet), PI-4 (p-toluenesulfonamide), and D-1 (malachite green). Solvents include: Sol-1 (methanol), Sol-2 (toluene), ZJ-2 (leveling agent), and ZJ-3 (defoamer); Additives include: first additive and / or second additive.

[0036] Based on this material, Examples 1 to 5 were carried out.

[0037] Example 1 To prepare photosensitive adhesive and photosensitive dry film, 0.01%-5% diethylaminoethyl methacrylate is added to the resin. Alternatively, 0.01%-5% diethylaminoethyl methacrylate is added to the adhesive solution, and the adhesive solution and polymer are mixed evenly. The mixture is stirred at 75-85℃ for 2 hours to allow for reflux reaction, resulting in thermal polymerization and primary crosslinking. After standing for 2 hours, the mixture is stirred at 65-80℃ for dense crosslinking reaction, filtered, and then allowed to undergo photopolymerization at 18-22℃ to obtain the photosensitive adhesive solution. After being placed for 0, 7, 14, and 21 days, the photosensitive adhesive solution is coated onto the surface of a 15μm thick PET support film using a coating machine. The film is then baked at 80℃ for 10 minutes to obtain a 15μm thick photosensitive layer. Finally, a PE film is coated onto the surface of the photosensitive layer for protection, completing the preparation of the photosensitive dry film.

[0038] Table 1 Performance Results

[0039] Analysis of the experimental data shows that by adding tertiary amine-containing acrylic (amide) monomers (such as diethylaminoethyl methacrylate) to the photosensitive resin system and using a gradient crosslinking process, the performance of the present invention is significantly improved compared with the blank control group (experimental group 13, without adding the monomer and without using the gradient crosslinking process) and the experimental group without using the gradient crosslinking process. Experimental data show that as the addition of diethylaminoethyl methacrylate (DEME) increases from 0.01% to 5%, the 10-day viscosity change rate of the photosensitive adhesive decreases from 13.3% to 8.5%, the 10-day hue change rate decreases from 14.8% to 8.5%, the shelf life of the photosensitive adhesive increases from 10 days to 18 days, and the shelf life of the photosensitive dry film increases from 10 months to 16 months. At the same addition amount, compared with the experimental groups without gradient crosslinking (e.g., experimental groups 2, 4, and 6), the experimental groups using gradient crosslinking technology (e.g., experimental groups 1, 3, and 5) show a 0.2%~0.3% reduction in viscosity change rate and hue change rate, a 1~2-day extension in the shelf life of the photosensitive adhesive, and a 1-month extension in the shelf life of the photosensitive dry film. This indicates that the monomer and the gradient crosslinking process have a synergistic effect. The above data fully demonstrates that the acrylic functional groups in this monomer can promote resin crosslinking and improve structural density, while the tertiary amine groups can form stable complexes with the acid components of the system, inhibiting side reactions and playing a photosensitizing role. It also works synergistically with photoinitiators to reduce exposure energy, effectively solving the problems of hue drift, abnormal viscosity increase, and photosensitivity decay during adhesive storage. Furthermore, it improves the dry film formation quality, adhesion, and resolution, significantly optimizing the overall performance of the photosensitive material. It possesses clear technical advantages and practical value.

[0040] Example 2 Photosensitive adhesive and photosensitive dry film were prepared by adding 0.01%-5% EDTA to the adhesive solution while keeping other conditions unchanged.

[0041] Table 2 Performance Results

[0042] Analysis of the experimental data shows that, by adding a second additive, EDTA, to the adhesive system, the present invention can significantly improve the storage stability and overall performance of the photosensitive material compared to the blank control group (experimental group 13, without EDTA added, with an addition amount of 0) and experimental groups with different processes and different addition amounts. Experimental data show that as the EDTA addition increases from 0.01% to 5%, the 10-day viscosity change rate of the photosensitive emulsion decreases from 13.5% to 7.0%, the 10-day hue change rate decreases from 14.6% to 8.32%, the shelf life of the photosensitive emulsion increases from 10 days to 17 days, and the shelf life of the photosensitive dry film increases from 10 months to 16 months. Under the same EDTA addition, compared with the experimental groups without gradient crosslinking (such as experimental groups 2, 4, and 6), the experimental groups using gradient crosslinking technology (such as experimental groups 1, 3, and 5) showed a 0.2%~0.3% decrease in viscosity change rate, a 0.3%~0.4% decrease in hue change rate, the same or extended shelf life of the photosensitive emulsion by 1 day, and an extended shelf life of the photosensitive dry film by 1 month. This indicates that EDTA and gradient crosslinking technology have a synergistic effect. The above data fully demonstrates that when EDTA is added as a second additive to the adhesive system, it can form a complex system with the system. By "encapsulating" and adsorbing metal ions and preventing their re-release, it effectively reduces the interference of metal ions on the system. Metal ions are a key factor leading to resin degradation and photosensitivity decline. At the same time, EDTA can also play a synergistic role in promoting cross-linking and initiating photopolymerization, further improving the stability of the photopolymerization reaction. It not only effectively solves the problems of color drift, abnormal viscosity increase and photosensitivity decay during adhesive storage, but also optimizes the performance of photosensitive materials and significantly extends the shelf life of photosensitive adhesives and dry films. This fully proves that adding EDTA as a second additive to the adhesive can effectively improve the storage stability of the product, and has clear technical advantages and practical value.

[0043] Example 3 EDTA and diethylaminoethyl methacrylate were added to the adhesive solution, totaling 5%, to prepare the photosensitive adhesive solution.

[0044] Table 3 Performance Results

[0045] Analysis of the experimental data shows that this invention, by adding diethylaminoethyl methacrylate and EDTA as additives to the adhesive system, significantly improves the storage stability and overall performance of the photosensitive material compared to the blank control group (experimental group 13, with both additives added at 0%) and experimental groups with different processes and ratios. Experimental data shows that when the total amount of diethylaminoethyl methacrylate and EDTA is adjusted within a 5% range, the various properties of the photosensitive material exhibit regular changes: when both are present (0.01% diethylaminoethyl methacrylate and 4.99% EDTA), the viscosity change rate of the photosensitive adhesive after 10 days is 13.0%, the hue change rate is 14.2%, the adhesive shelf life is 10 days, and the dry film shelf life is 12 months. With adjustments to the ratio, the various properties are gradually optimized, reaching their optimal state when both are added at 2.5% (total 5%), at which point the viscosity change rate of the photosensitive adhesive after 10 days decreases to 4.3%. The color change rate was reduced to 5.4%, the shelf life of the adhesive solution was extended to 21 days, and the shelf life of the dry film was increased to 18 months, all of which were the best levels among all experimental groups. Under the same total amount of additives, compared with the experimental groups without gradient crosslinking process (such as experimental groups 2, 4, and 6), the experimental groups using gradient crosslinking process (such as experimental groups 1, 3, and 5) had a viscosity change rate reduced by 0.2%~0.5%, a color change rate reduced by 0.2%~0.3%, a shelf life of the adhesive solution remained the same or extended by 1 day, and a dry film shelf life extended by 1 month, indicating that the dual-additive compound system and gradient crosslinking process have a synergistic effect. The above data fully demonstrates that this compound system, through the modification effect of the "tertiary amine-acrylic acid double bond structure," achieves the synergistic effect of the tertiary amine group (complexing, co-initiating, and anti-aging) and the acrylic acid double bond structure (crosslinking, anti-photopolymerization) in diethylaminoethyl methacrylate. Simultaneously, it takes into account the functions of EDTA in adsorbing metal ions, promoting crosslinking, and co-initiating photopolymerization, forming a "multi-functional integrated improvement" effect. This effectively inhibits metal ion-induced resin degradation, reduces photopolymerization interference, and solves the problems of color drift, abnormal viscosity increase, and photosensitivity decay during adhesive storage. It significantly extends the shelf life of photosensitive adhesives and dry films, fully proving that this compounding scheme can effectively improve product storage stability and possesses clear technical advantages and practical value.

[0046] Example 4 A photosensitive dry film, from bottom to top, comprises a PET layer, a photosensitive resist layer formed by coating and drying the photosensitive adhesive solutions described in Examples 1, 2, and 3 onto the surface of the PET layer, and a PE layer. The photosensitive adhesive solutions described above are coated onto the surface of a 15 μm thick PET support film using a coating machine. The film is baked at 80°C for 10 minutes to obtain a photosensitive layer with a thickness of 15 μm. Finally, a PE film is applied to the surface of the photosensitive layer for protection, completing the preparation of the photosensitive dry film. Photosensitive dry films were prepared by placing the photosensitive adhesive solutions from Examples 1, 2, and 3, which employ a gradient crosslinking process, for 0, 7, 14, and 21 days, respectively.

[0047] Table 4. Photosensitive properties of dry films prepared by leaving the adhesive solution for a period of time.

[0048] Based on the experimental data of dry film qualification rate, the photosensitive adhesive prepared in Examples 1, 2, and 3 achieved a qualification rate of over 90% when preparing photosensitive dry films at various time points of 0 days, 7 days, 14 days, and 21 days of storage. Among them, the highest qualification rate reached 92% at 21 days of storage. This further verifies that the photosensitive adhesive prepared by this compounding scheme has good storage stability and practical application feasibility, fully demonstrating that this scheme can effectively improve the overall quality of the product and has clear technical advantages and practical value.

[0049] Example 5 The application of photosensitive dry film involved placing the photosensitive dry film for 0, 6, 12, and 18 months, followed by film application. A copper-clad laminate with a 35μm thick rolled 1.2mm thick copper foil was subjected to surface treatments including polishing, micro-etching, washing, and drying, and then preheated to 80℃. The laminating machine's pressure roller temperature was set to 110℃, air pressure to 0.35MPa, and lamination speed to 1.5m / min. After removing the PE protective film from the surface of the photosensitive dry film obtained in the above examples and comparative examples, the aforementioned photosensitive resin composition was laminated onto the copper-clad laminate to obtain the substrate. Exposure: After film application, the sample was allowed to stand for 20 minutes and then exposed using an exposure machine (model: MAS-04L10-8, Xinge Micro, main wavelength 405nm). The photosensitivity was tested using a Stouffer 41-level step exposure scale, with the exposure count controlled between 15-22 divisions. Development: After exposure, the sample is left to stand for more than 20 minutes, the PET support film is peeled off, and the sample is developed using an alkaline developer (manufactured by Guangzhou Julong Printed Circuit Board Equipment Co., Ltd.). A 1wt% Na2CO3 aqueous solution at 30°C is sprayed for twice the minimum development time. After development, the sample is washed with water and dried to obtain the cured film substrate.

[0050] Table 5. Pass rate of photosensitivity in actual application after dry film has been stored for a period of time.

[0051] Further verification was conducted through practical application experiments of the photosensitive dry film. Following the standard process (copper-clad laminate surface treatment → preheating → film application → exposure → development), the photosensitive dry films prepared in Examples 1, 2, and 3 were placed for 0, 6, 12, and 18 months, respectively, before being put into production. The data on the pass rate of their photosensitive performance showed that the dry films of different groups in each example maintained a high pass rate at each storage time point, with an overall pass rate of over 90%. The highest pass rate was still 92% after 18 months of storage, and even with the longest storage time (18 months), the lowest pass rate still reached 79%, which was far better than the performance of the blank control group. This further fully verified that the photosensitive adhesive and dry film prepared by the compounding scheme of this invention have excellent long-term storage stability and reliable practical application value, highlighting the technical advantages and industrial application potential of this scheme.

[0052] In summary, based on the analysis of all experimental data from the five embodiments described above, it can be concluded that this invention, through the compounding of a first additive (diethylaminoethyl methacrylate) and a second additive (EDTA), combined with a gradient crosslinking process, achieves a significant breakthrough in the storage stability and application performance of photosensitive materials, thus fulfilling the preset technical objectives. Compared with traditional photosensitive materials, the technical advantages of this application are particularly prominent: the shelf life of traditional photosensitive adhesive is only 10 days, while the shelf life of the photosensitive adhesive prepared by this invention is more than 21 days; the shelf life of traditional photosensitive dry film is 12 months, while the shelf life of the photosensitive dry film prepared by this invention is extended to more than 18 months, with the shelf life more than doubled. Furthermore, the photosensitive dry film prepared by this invention, even after long-term storage (up to 18 months) before production application, retains ≥90% of its photosensitive performance and can normally form photolithography templates. This effectively solves the technical pain points of short shelf life and severe performance degradation after long-term storage of traditional photosensitive materials, reduces material waste caused by expired photosensitive adhesive and dry film performance failure, and lowers production costs. Comparative experiments with different ratios and processes in five embodiments further confirmed that the dual-additive compound system and gradient crosslinking process have a synergistic effect. The best effect was achieved when 2.5% of diethylaminoethyl methacrylate and EDTA were added (5% total), with all performance indicators reaching their peak values. This fully verified the scientific nature, feasibility, and superiority of the technical solution of this invention, providing reliable technical support for the industrial application of photosensitive materials. It has extremely high practical application value and industrial promotion potential.

[0053] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A photosensitive glue solution, characterized in that, The raw material composition includes, in parts by weight: 48-65 parts of polymer, 36-50 parts of monomer, 0.5-5 parts of photoinitiator, 5-25 parts of solvent, and 0.01-5.0 parts of additive; The additive includes a first additive and / or a second additive; The first additive is a tertiary amine-containing acrylic monomer, i.e., a compound represented by general formula I: Formula I The structural core of the first additive is acryloyl X+connection chain Y+tertiary amine group Z, including two forms: Form One: ; X is CH2=CHCOO- and Y is an alkylene group -(CH2) n - any one of hydroxyalkyl -OHR-, ester group -COOR-; R, R1, R2 are any one of hydroxyl, alkyl with carbon number 1-12, benzoyloxy, aromatic group; R3 is any one of hydrogen atom, alkyl, hydrocarbon group; Form two: ； X is acrylamide CH2=CHCON-, Y is alkylene -(CH2) n - any one of hydroxyalkyl -OHR-, ester group -COOR-; R, R1, R2 are respectively any one of alkyl with carbon number 1-12, benzoyloxy, aromatic group; R3 is any one of hydrogen atom, alkyl, hydrocarbon group; The second additive is a compound represented by general formula II: Formula II Wherein n is 1-3; represents the main structure; R, R1, R2, R3, R4, R5 all exist 1-6, represent carboxyl, and ring, hydroxyl, phenolic group, methyl can also be introduced to chemically modify carboxyl.

2. The photosensitive resist solution according to claim 1, wherein The first additive is selected from any one of the substances contained in Form One of general formula I: methacrylate diethylaminoethyl, methacrylate dimethylaminoethyl, acrylate diethylaminoethyl, methacrylate dimethylamino propyl, methacrylate morpholinoethyl, acrylate morpholinoethyl, methacrylate tertiary butyl amino ethyl; Or the first additive is selected from any one of the substances contained in Form Two of general formula I: N-(3-dimethylaminopropyl) methacrylamide, N, N-dimethyl acrylamide, N, N-diethyl acrylamide, N, N-dimethyl methacrylamide; or the first additive is methacrylate diethylaminoethyl.

3. The photosensitive glue solution according to claim 1, characterized in that, The second additive is selected from one of the substances contained in general formula II, which is any one of ethylenediaminetetraacetic acid EDTA, tetramethyl ethylenediamine TMEDA, diethylenetriamine pentaacetic acid DTPA, nitrilotriacetic acid NTA, hydroxyethyl ethylenediamine triacetic acid HEDTA, glutamic acid diacetic acid tetrasodium GLDA, triethylenetetramine hexaacetic acid 1, 2-cyclohexanediamine tetraacetic acid, nitrilotriacetic acid NTA, or the second additive is ethylenediaminetetraacetic acid EDTA.

4. A method for preparing a photosensitive glue solution, characterized by, The method includes the following steps: Step 1, add the first additive to 48-65 parts of polymer, mix uniformly, stand still, and make it fully react; Step 2, mix monomer 36-50 parts, photoinitiator 0.5-5 parts, solvent 5-25 parts, and second additive, stir, and make them fully mix to obtain glue liquid; The sum of the weights of the first additive and the second additive is 0.01%-5%: Step 3, mix the glue liquid and the polymer by temperature control stirring, filter, and obtain photosensitive glue liquid; Step 4, coat the photosensitive glue liquid, dry, and compound to obtain photosensitive dry film.

5. A method for preparing a photosensitive glue solution, characterized by, The method includes the following steps: Step 1, prepare 48-65 parts of polymer; Step 2, mix monomer 36-50 parts, photoinitiator 5-5 parts, and solvent 5-25 parts, mix the first additive and / or the second additive with a total amount of 0.01%-5% parts, stir, and make them fully mix to obtain glue liquid; Step 3, mix the glue liquid and the polymer by temperature control stirring, filter, and get photosensitive glue liquid; Step 4, coat the photosensitive glue liquid, dry, and complex to obtain photosensitive dry film.

6. The method for preparing the photosensitive adhesive according to any one of claims 4 to 5, characterized in that, In the process of stirring and mixing the glue liquid and the polymer, a temperature gradient is set to realize staged control of crosslinking reaction.

7. The method of claim 6, wherein the photosensitive resist solution is prepared by adding the compound of formula (I) to the solvent. The temperature gradient is specifically: the temperature of the primary cross-linking is 75-85℃, the temperature of the dense cross-linking is 65-80℃, and finally the temperature is reduced to 18-22℃ for light monomer compounding.

8. A photosensitive dry film characterized by comprising: It is obtained by coating and drying compounding with the photosensitive glue solution of any one of claims 4-6.

9. A photosensitive dry film characterized by comprising: The photosensitive dry film comprises a PET layer from bottom to top, a photosensitive resist layer formed by coating and drying the photosensitive glue solution of any one of claims 4-5 on the surface of the PET layer, and a PE layer.

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