Fluorine-containing bismaleimide alkali-soluble resin, preparation method thereof, photoresist and application

Abstract

The invention belongs to the technical field of modification of bismaleimide resin, and particularly relates to fluorine-containing bismaleimide alkali-soluble resin, a preparation method thereof, photoresist and application of the fluorine-containing bismaleimide alkali-soluble resin. The invention provides a low-dielectric fluorine-containing bismaleimide monomer which is generated by carrying out imidization reaction on maleic anhydride and fluorine-containing ether bond diamine. The invention also provides fluorine-containing bismaleimide alkali-soluble resin. The fluorine-containing bismaleimide alkali-soluble resin is obtained by blending and reacting the following components in parts by weight: a fluorine-containing bismaleimide monomer, cyanate ester, polyphenyl ether, a polar solvent and a photoinitiator. The fluorine-containing bismaleimide alkali-soluble resin disclosed by the invention is suitable for a low dielectric medium layer or a photoresist functional component in an OLED (Organic Light Emitting Diode) capacitive touch device, and the problems that the existing material is insufficient in dielectric property, unstable in comprehensive performance and poor in device process compatibility are solved.

Description

Technical Field

[0001] This invention belongs to the field of bismaleimide resin modification technology, specifically relating to a fluorinated bismaleimide alkali-soluble resin, its preparation method, photoresist, and applications. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are electroluminescent devices that utilize a multilayer organic thin-film structure. They offer advantages such as ease of fabrication, low driving voltage, high brightness, low power consumption, fast response, high resolution, high luminous efficiency, wide viewing angle, and thinness and flexibility, meeting consumers' evolving demands for display technology. In the construction of OLED devices, capacitive touch devices place stringent requirements on the dielectric constant of the materials. The larger the display area, the lower the dielectric constant of the touch device material is needed to improve touch performance. Currently, silicon nitride is commonly used as the dielectric in touch devices, but its high dielectric constant reduces touch sensitivity, and this effect becomes more pronounced with larger display areas. Therefore, the industry is seeking to replace silicon nitride with transparent photoresist materials with low dielectric constants.

[0003] Bismaleimide resins have attracted attention as alternatives to silicon nitride materials due to their excellent resistance to damp heat, mechanical properties, chemical resistance, and superior dielectric properties. However, the dielectric properties of bismaleimide resins are still insufficient to meet the needs of current technological development, and ordinary bismaleimide resins do not contain carboxyl groups and are not alkali-soluble, making them unsuitable for use as photoresist resins. Therefore, it is necessary to modify them to further reduce the dielectric constant and improve alkali solubility.

[0004] Regarding dielectric constant, commonly used modification methods include: (1) blending with resins with excellent dielectric properties such as polytetrafluoroethylene, polyphenylene ether, and cyanate esters; and (2) introducing nano-void structures. However, the above modification methods still cannot optimize the dielectric properties to meet the touch sensitivity of the display screen, and will also lead to unstable performance, poor compatibility with device processes, and increased risk of moisture absorption, which will damage long-term reliability.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a fluorinated bismaleimide alkali-soluble resin with low dielectric constant and excellent comprehensive performance, as well as its preparation method, photoresist and application. This fluorinated bismaleimide alkali-soluble resin is suitable for low dielectric layer or photoresist functional component in OLED capacitive touch devices, solving the problems of insufficient dielectric properties, unstable comprehensive performance and poor compatibility with device processes of existing materials.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a low-dielectric fluorinated bismaleimide monomer, wherein the fluorinated bismaleimide monomer is generated by an imidization reaction of maleic anhydride and a fluorinated ether diamine, and its general structural formula is shown in the following formula (1): Equation (1) In the formula, R1 and R2 may be the same or different, and are independently selected from H and C. 1～6 Alkyl, fluorine-substituted C 1～6 One or more alkyl groups; R3 and R4 may be the same or different, each independently selected from perfluorinated C4 groups. 1～6 Alkyl or phenyl.

[0008] Furthermore, the molar ratio of maleic anhydride to fluorinated ether diamine is 2:1; The general structural formula of the maleic anhydride is shown in equation (2) below: Equation (2) In the formula, R1 and R2 may be the same or different, and are independently selected from H and C. 1～6 Alkyl, fluorine-substituted C 1～6 One or more of alkyl groups; The general structural formula of the fluorinated ether diamine is shown in formula (3) below: Equation (3) In the formula, R3 and R4 may be the same or different, and each is independently selected from perfluorinated C3. 1～6 Alkyl or phenyl.

[0009] Preferably, perfluoroethyl is preferred over perfluoromethyl for R3 and R4. When perfluoroethyl is used, the dielectric constant of the resin decreases by 0.1 to 0.2 compared to perfluoromethyl.

[0010] Furthermore, the maleic anhydride comprises the following structure: Equation (2-1) Equation (2-2) Equation (2-3) Equation (2-4) Equation (2-5) Equation (2-6) Equation (2-7) Equation (2-8) Equation (2-9) Equation (2-10).

[0011] Furthermore, the fluorinated ether diamine comprises the following structure: Equation (3-1) Equation (3-2) Equation (3-3).

[0012] Secondly, the present invention provides a low-dielectric fluorinated bismaleimide alkali-soluble resin, based on the carboxyl-containing low-dielectric fluorinated bismaleimide monomer described above, obtained through a blending reaction of the following components, having a number-average molecular weight (Mw) of 4000-10000 and a molecular weight distribution index (PDI) of 1.4-2.5; comprising, based on 100 parts by weight of the total weight of the components, the following components are included: Fluorinated bismaleimide monomer: 10-25 parts; cyanate ester: 5-20 parts; polyphenylene ether: 5-15 parts; polar solvent: 45-65 parts; initiator: 0.1-2 parts.

[0013] Furthermore, the cyanate ester includes any one of bisphenol A cyanate ester, bisphenol E cyanate ester, and phenolic cyanate ester; The polar solvent includes any one of propylene glycol methyl ether acetate (PGMEA), N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO); The initiator includes any one of azobisisobutyronitrile, azobisisoheptanenitrile, and dicumyl peroxide.

[0014] Thirdly, the present invention provides a method for preparing a low-dielectric fluorinated bismaleimide alkali-soluble resin, for preparing the fluorinated bismaleimide alkali-soluble resin as described above, comprising the following steps: Step 1: In a reaction vessel, add maleic anhydride, fluorinated ether diamine and polar solvent. Stir the reaction at room temperature under inert gas protection, then heat to the set temperature and react at a constant temperature to obtain a solution of fluorinated bismaleimide monomer. Step 2: When the solution obtained in Step 1 is at the set temperature, add cyanate ester to the solution and stir until it is completely dissolved to obtain a transparent solution; Step 3: When the transparent solution obtained in step 2 is at the set temperature, add polyphenylene ether and initiator to the transparent solution to react and obtain a low dielectric fluorinated bismaleimide alkali-soluble resin.

[0015] Furthermore, in step 1, the reaction is stirred at room temperature for 2-4 hours, then heated to 80-150℃ and kept at that temperature for 2-3 hours. In step 2, the set temperature of the solution is 80~110℃; In step 3, the temperature of the transparent solution is set at 120~140℃, and the reaction time is 0.5~3h.

[0016] Fourthly, the present invention provides a low-dielectric photoresist comprising the following components in parts by weight: 8-15 parts of fluorinated bismaleimide alkali-soluble resin, 4-8 parts of reactive diluent, 3-6 parts of alkali-soluble acrylate monomer, 1.5-3 parts of photoinitiator, and 25-75 parts of solvent, wherein the fluorinated bismaleimide alkali-soluble resin is the fluorinated bismaleimide alkali-soluble resin as described above, or the fluorinated bismaleimide alkali-soluble resin prepared based on the preparation method described above.

[0017] Fifthly, the present invention provides an application of a low-dielectric fluorinated bismaleimide alkali-soluble resin, based on the fluorinated bismaleimide alkali-soluble resin as described above, or the fluorinated bismaleimide alkali-soluble resin prepared by the preparation method as described above, in the preparation of OLED capacitive touch devices.

[0018] Specifically, the fluorinated bismaleimide alkali-soluble resin can be used to prepare the dielectric layer in OLED capacitive touch devices; Alternatively, it can be introduced into the photoresist formulation as a key functional component to significantly reduce the dielectric constant of the photoresist. Adding the fluorinated bismaleimide alkali-soluble resin of this invention to a low-dielectric photoresist formulation effectively reduces the dielectric constant of the photoresist (2.75–2.95) without affecting other properties of the photoresist.

[0019] The formulation includes the following: 8-15 parts of fluorinated bismaleimide alkali-soluble resin, 4-8 parts of reactive diluent, 3-6 parts of alkali-soluble acrylate monomer, 1.5-3 parts of photoinitiator, and 25-75 parts of solvent.

[0020] The reactive diluent includes a fluorinated acrylate monomer, wherein the fluorinated acrylate monomer is selected from any one of hexafluoroisopropyl diacrylate, hexafluorobutyl (meth)acrylate, perfluoropolyether acrylate, and trimethylolpropane triacrylate.

[0021] The alkali-soluble acrylate monomer is used to provide alkali solubility (developability), adjust film formation, and adhesion. This alkali-soluble acrylate monomer includes carboxyl-containing acrylic monomers, such as (meth)acrylic acid, and any one of methacryloyloxyethyl maleic acid monoester and β-(acryloyloxy)propionic acid.

[0022] The solvent includes any one of diacetone alcohol, cyclohexanone, N-methyl-2-pyrrolidone, diethylene glycol ethyl methyl ether, propylene glycol methyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethyl acetate, ethyl lactate, and propylene glycol methyl ether acetate.

[0023] The photoinitiator (free radical photoinitiator) is selected from any one of TPO, TEPO, OXE-01, OXE-02, 1173, 184, and 819.

[0024] Compared with the prior art, the present invention has the following beneficial effects: The fluorinated bismaleimide alkali-soluble resin provided by this invention possesses excellent dielectric properties. The bismaleimide monomer it contains contains fluorine atoms, which helps reduce the resin's polarization ability and increase the polymer's free volume, thereby lowering the resin's dielectric constant. Furthermore, the ether bonds are highly flexible, improving the resin's film-forming properties, adhesion, and flexibility. This application introduces carboxyl groups into the molecular structure of the fluorinated bismaleimide monomer and prepares the alkali-soluble bismaleimide resin through thermal polymerization. This resin can be used in photoresists.

[0025] Specifically, through fluorine atom modification, flexible ether bond design, and synergistic effects with cyanate ester / polyphenylene ether, the blended resin exhibits an extremely low dielectric constant (up to 2.75-2.95 (1MHz, 25℃)), significantly lower than traditional bismaleimide resins (typically >3.2). The resin demonstrates good process compatibility; adding fluorinated bismaleimide alkali-soluble resin to photoresist can significantly reduce the dielectric constant, improve photoresist development uniformity, reduce edge roughness, and result in good film formation and strong adhesion. It is suitable for micro-processing techniques such as spin coating and photolithography without affecting key indicators such as resolution. While maintaining high light transmittance (>98%), it also possesses good thermal stability and chemical resistance, making it widely applicable and highly adaptable. Detailed Implementation

[0026] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0027] Preparation Example 1 This preparation example provides the preparation of a low-dielectric fluorinated bismaleimide alkali-soluble resin, wherein the low-dielectric fluorinated bismaleimide alkali-soluble resin M-1 comprises the following components in parts by weight: Fluorinated bismaleimide monomer (formula (a)): 15 parts; bisphenol A cyanate: 20 parts; polyphenylene ether: 12 parts; propylene glycol methyl ether acetate: 45 parts; azobisisobutyronitrile: 1 part.

[0028] The specific preparation method is as follows: Maleic anhydride monomer (Formula 2-1) and fluorinated ether-bonded diamine monomer (Formula 3-1) are added to a four-necked flask in a molar ratio of 2:1, along with 100 mL of propylene glycol methyl ether acetate solution. The mixture is stirred at room temperature for 3 h under inert gas protection, then slowly heated to 140 °C and reacted at this temperature for 2 h to obtain a fluorinated bismaleimide monomer solution. The inert atmosphere can be nitrogen. When the temperature of the fluorinated bismaleimide monomer solution is 100°C, bisphenol A cyanate is added to the solution and stirred until completely dissolved to obtain a transparent solution. When the temperature of the transparent solution is 120℃, polyphenylene ether and azobisisobutyronitrile are added to the transparent solution, and the reaction is carried out at 120℃ for 3 hours until the resin is uniform and transparent, resulting in a low dielectric fluorinated bismaleimide alkali-soluble resin with a dielectric constant of 2.75.

[0029] The structure of the fluorinated bismaleimide monomer in this preparation example: Equation (a) Preparation Example 2 This preparation example provides a method for preparing a low-dielectric fluorinated bismaleimide alkali-soluble resin, wherein the low-dielectric fluorinated bismaleimide alkali-soluble resin M-2 is selected from the following components in parts by weight: Fluorinated bismaleimide monomer (formula (b)): 20 parts; bisphenol E cyanate: 15 parts; polyphenylene ether: 10 parts; N,N-dimethylformamide: 50 parts; dicumyl peroxide: 1 part.

[0030] The specific preparation method is as follows: Maleic anhydride monomer (Formula 2-2) and fluorinated ether-bonded diamine monomer (Formula 3-2) are added to a four-necked flask in a molar ratio of 2:1, along with 100 mL of N,N-dimethylformamide solution. The mixture is stirred at room temperature for 2 h under inert gas protection, then slowly heated to 150 °C and kept at that temperature for 3 h to obtain a fluorinated bismaleimide monomer solution. The inert atmosphere can be nitrogen. When the temperature of the fluorinated bismaleimide monomer solution is 110°C, bisphenol E cyanate is added to the solution and stirred until completely dissolved to obtain a transparent solution. When the temperature of the transparent solution is 130℃, polyphenylene ether and dicumyl peroxide are added to the transparent solution, and the reaction is carried out at 130℃ for 1.5h until the resin is uniform and transparent, and a low dielectric fluorinated bismaleimide alkali-soluble resin with a dielectric constant of 2.82 is obtained.

[0031] The structure of the fluorinated bismaleimide monomer in this preparation example: Equation (b) Preparation Example 3 This preparation example provides a method for preparing a low-dielectric fluorinated bismaleimide alkali-soluble resin, wherein the low-dielectric fluorinated bismaleimide alkali-soluble resin M-3 is selected from the following components in parts by weight: Fluorinated bismaleimide monomer (formula (c)): 25 parts; phenolic cyanate ester: 10 parts; polyphenylene ether: 10 parts; N,N-dimethylformamide: 55 parts; azobisisobutyronitrile: 1.5 parts.

[0032] The specific preparation method is as follows: Maleic anhydride monomer (Formula 2-3) and fluorinated ether-bonded diamine monomer (Formula 3-3) are added to a four-necked flask in a molar ratio of 2:1, along with 100 mL of N,N-dimethylformamide solution. The mixture is stirred at room temperature for 4 h under inert gas protection, then slowly heated to 120 °C and held at that temperature for 1.5 h to obtain a fluorinated bismaleimide monomer solution. The inert atmosphere can be nitrogen. When the temperature of the fluorinated bismaleimide monomer solution is 80°C, phenolic cyanate is added to the solution and stirred until completely dissolved to obtain a transparent solution. When the temperature of the transparent solution is 120℃, polyphenylene ether and azobisisobutyronitrile are added to the transparent solution, and the reaction is carried out at 120℃ for 3 hours until the resin is uniform and transparent, resulting in a low dielectric fluorinated bismaleimide alkali-soluble resin with a dielectric constant of 2.85.

[0033] The structure of the fluorinated bismaleimide monomer in this preparation example: Equation (c) Preparation Example 4 This preparation example provides a method for preparing a low-dielectric fluorinated bismaleimide alkali-soluble resin, wherein the low-dielectric fluorinated bismaleimide alkali-soluble resin M-4 is selected from the following components in parts by weight: Fluorinated bismaleimide monomer (formula (d)): 10 parts; bisphenol A cyanate: 10 parts; polyphenylene ether: 8 parts; N-methylpyrrolidone: 65 parts; azobisisobutyronitrile: 1.5 parts.

[0034] The specific preparation method is as follows: Maleic anhydride monomer (Formula 2-8) and fluorinated ether-bonded diamine monomer (Formula 3-1) are added to a four-necked flask in a molar ratio of 2:1, along with 100 mL of N-methylpyrrolidone solution. The mixture is stirred at room temperature for 4 h under inert gas protection, then slowly heated to 80 °C and held at that temperature for 1.5 h to obtain a fluorinated bismaleimide monomer solution. The inert atmosphere can be nitrogen. When the temperature of the fluorinated bismaleimide monomer solution is 100°C, bisphenol A cyanate is added to the solution and stirred until completely dissolved to obtain a transparent solution. When the temperature of the transparent solution is 140℃, polyphenylene ether and azobisisobutyronitrile are added to the transparent solution, and the reaction is carried out at 140℃ for 0.5h until the resin is uniform and transparent, resulting in a low dielectric fluorinated bismaleimide alkali-soluble resin with a dielectric constant of 2.90.

[0035] The structure of the fluorinated bismaleimide monomer in this preparation example: Equation (d) Preparation Example 5 This preparation example provides a method for preparing a bismaleimide resin, which uses the following components in parts by weight: NE-X 9600 (source: commercially available bismaleimide resin from DIC Corporation): 15 parts; bisphenol A cyanate: 20 parts; polyphenylene ether: 12 parts; propylene glycol methyl ether acetate: 45 parts; azobisisobutyronitrile: 1 part. The components were blended in the above proportions to obtain a bismaleimide resin with a dielectric constant of 3.1.

[0036] In the above preparation examples, the four-necked flasks used were all equipped with thermometers, stirrers, and reflux condensers.

[0037] Example 1 This embodiment provides an application of a fluorinated bismaleimide alkali-soluble resin. Preparation Example 1 is added to a low-dielectric photoresist formulation, which includes the following components in parts by weight: Preparation Example 1: 8 parts M-1, 4 parts hexafluoroisopropyl diacrylate, 3 parts (meth)acrylic acid, 50 parts propylene glycol methyl ether, and 2 parts TPO.

[0038] Example 2 This embodiment provides an application of a fluorinated bismaleimide alkali-soluble resin. Preparation Example 1 is added to a low-dielectric photoresist formulation, which includes the following components in parts by weight: Preparation Example 1: 10 parts M-1, 5 parts hexafluoroisopropyl diacrylate, 3 parts (meth)acrylic acid, 60 parts propylene glycol methyl ether, and 2 parts TPO.

[0039] Example 3 This embodiment provides an application of a fluorinated bismaleimide alkali-soluble resin. Preparation Example 2 is added to a low-dielectric photoresist formulation, which includes the following components in parts by weight: Preparation Example 2: 12 parts of M-2, 6 parts of hexafluorobutyl (meth)acrylate, 4 parts of methacryloyloxyethyl maleic acid monoester, 70 parts of dipropylene glycol monomethyl ether, and 2 parts of TEPO.

[0040] Example 4 This embodiment provides an application of a fluorinated bismaleimide alkali-soluble resin. Preparation Example 3 is added to a low-dielectric photoresist formulation, which includes the following components in parts by weight: Preparation Example 3: 15 parts of M-3, 8 parts of trimethylolpropane triacrylate, 4 parts of methacryloyloxyethyl maleic acid monoester, 75 parts of dipropylene glycol monomethyl ether, and 3 parts of OXE-02.

[0041] Example 5 This embodiment provides an application of a fluorinated bismaleimide alkali-soluble resin. Preparation Example 4 is added to a low-dielectric photoresist formulation, which includes the following components in parts by weight: Preparation Example 4: 15 parts of M-4, 6 parts of trimethylolpropane triacrylate, 6 parts of β-(acryloyloxy)propionic acid, 60 parts of cyclohexanone, and 4 parts of OXE-01.

[0042] Comparative Example 1 This comparative example provides a photoresist whose formulation includes the following components in parts by weight: Preparation Example 5 8 parts, hexafluoroisopropyl diacrylate 4 parts, (meth)acrylic acid 3 parts, propylene glycol methyl ether 50 parts, and TPO 2 parts.

[0043] Comparative Example 2 This comparative example provides a photoresist whose formulation includes the following components in parts by weight: 5 parts hexafluoroisopropyl diacrylate, 3 parts (meth)acrylic acid, 60 parts propylene glycol methyl ether, and 2 parts TPO.

[0044] Comparative Example 3 This comparative example provides a photoresist whose formulation includes the following components in parts by weight: 12 parts of M-2 from Preparation Example 2, 6 parts of hexafluorobutyl (meth)acrylate, 4 parts of alicyclic epoxy monomer, 70 parts of propylene glycol methyl ether, and 2 parts of TEPO.

[0045] To demonstrate that adding the fluorinated bismaleimide alkali-soluble resin of the present invention to the photoresist does not affect other properties, the inventors tested the performance of the photoresists in all embodiments and comparative examples, including the following aspects: (1) Transmittance: The transmittance of the single film (with a film thickness of 3.5 μm) obtained after photolithography is tested at 380 nm to 800 nm using a UV spectrophotometer.

[0046] (2) Resolution (linewidth accuracy): The photoresist composition was spin-coated onto the glass slide at a speed of 160 r / min. After pre-baking at 85°C to remove the solvent, the resolution was 120 mJ / cm. 2 The mask is exposed at low energy, and the pattern is obtained after development.

[0047] (3) Adhesion: The coating is cut into 100 grids using a cross-cutting tool and a utility knife; 3M transparent tape is applied to the grids and pressure is applied to ensure the tape adheres firmly to the coating surface and the grid areas. The degree and extent of coating peeling on the substrate are visually inspected to determine its ASTM grade. The ASTM grades are as follows: 5B - Smooth cut edges, no peeling at the grid edges; 4B - Peeling area within the grid area ≤ 5%; 3B - Peeling area within the grid area > 5% to 15%; 2B - Peeling area within the grid area > 15% to 35%; 1B - Peeling area within the grid area > 35% to 65%; 0B - Peeling area within the grid area > 65%.

[0048] (4) Thermal stability (Td) 1% (i.e., the temperature corresponding to 1% weight loss): The test was conducted using a thermogravimetric analyzer (THA). Test conditions: test atmosphere N2; test temperature range: 35~400℃; heating rate: 10℃ / min.

[0049] (5) Dielectric constant: Using a precision impedance analyzer (4294A, Agilent Technologies): room temperature, Vdc=0V, Vac=100mV, test frequency range 40Hz~40MHz. Low-dielectric resin / photoresist is coated on ITO conductive glass, heated to 85℃ for solvent removal, and then thermo-cured / photo-cured. A specific area of ​​silver electrode is deposited on the thin film surface, or gold is sputtered to form an electrode. The dielectric constant is calculated using the following formula: 𝜀 𝑟 = (𝐶× d)⁄(𝜀0× 𝑆) where, C , d and S These are the material's capacitance, thickness, and electrode area, respectively. e 0 represents the vacuum permittivity. e 0 = 8.854 × 10 -12 F / m.

[0050] Test data is shown in Table 1: Table 1 The photoresist prepared in this invention has a transmittance greater than 98.5%. The fluorine-containing structure reduces light scattering and absorption, resulting in OLED devices with extremely high light extraction efficiency. The transmittance of the comparative examples is only around 94%. The resolution in all embodiments of this invention is 8 μm, significantly better than the comparative examples. The Td values ​​in all embodiments are... 1% All samples were heated above 160°C, and the adhesion reached 5B. This demonstrates that this method improves thermal stability without sacrificing interfacial bonding with the substrate. In contrast, the comparative samples showed weaker adhesion (2B) or detachment.

[0051] The combination of the fluorinated bismaleimide alkali-soluble resin and the fluorinated reactive diluent of the present invention can reduce the dielectric constant of the photoresist composition. In the comparative examples, neither the addition of the fluorinated bismaleimide alkali-soluble resin nor the addition of a commercially available bismaleimide resin reduced the dielectric constant of the formulation. Furthermore, Comparative Example 3, which added a cationic curing monomer (alicyclic epoxy monomer), required a cationic photoinitiator (such as thionium salt) and acidic conditions for effective curing. In the presence of the free radical initiator TPO of the present invention, the epoxy monomer could not be effectively cured. All properties deteriorated comprehensively; adhesion (2B) decreased due to weak areas at the interface. Phase separation led to light scattering, resulting in a decrease in transmittance (92.52%), and uneven curing affected pattern formation, also degrading the resolution (15 μm).

[0052] In summary, the fluorinated bismaleimide photoresist system of this invention achieves simultaneous and significant improvements in five aspects: low dielectric constant, high transparency, high heat resistance, strong adhesion, and high resolution. The transmittance of all embodiments is >98.5%, while the transmittance of the comparative examples is as low as approximately 92.52%. The dielectric constant of all embodiments is relatively low, ranging from 2.59 to 2.72, while the dielectric constant of the comparative examples is as high as 3.47 to 3.64. The Td of all embodiments... 1% All temperatures exceeded 160°C, and adhesion reached the highest level, 5B. The comparative example's Td... 1% Within the temperature range of 120~160℃, the adhesion rating is 2B or detachment. This demonstrates that the present invention improves thermal stability while maintaining interfacial adhesion to the substrate.

[0053] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0054] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A low-dielectric fluorinated bismaleimide monomer, characterized in that, The fluorinated bismaleimide monomer is generated by an imidization reaction of maleic anhydride and a fluorinated ether diamine, and its general structural formula is shown in formula (1) below: Equation (1) In the formula, R1 and R2 may be the same or different, and are independently selected from H and C. 1～6 Alkyl, fluorine-substituted C 1～6 One or more alkyl groups; R3 and R4 may be the same or different, each independently selected from perfluorinated C4 groups. 1～6 Alkyl or phenyl.

2. The low-dielectric fluorinated bismaleimide monomer according to claim 1, characterized in that, The molar ratio of maleic anhydride to fluorinated ether diamine is 2:1; The general structural formula of the maleic anhydride is shown in equation (2) below: Equation (2) In the formula, R1 and R2 may be the same or different, and are independently selected from H and C. 1～6 Alkyl, fluorine-substituted C 1～6 One or more of alkyl groups; The general structural formula of the fluorinated ether diamine is shown in formula (3) below: Equation (3) In the formula, R3 and R4 may be the same or different, and each is independently selected from perfluorinated C3. 1～6 Alkyl or phenyl.

3. The low-dielectric fluorinated bismaleimide monomer according to claim 2, characterized in that, The maleic anhydride comprises the following structure: Equation (2-1) Equation (2-2) Equation (2-3) Equation (2-4) Equation (2-5) Equation (2-6) Equation (2-7) Equation (2-8) Equation (2-9) Equation (2-10).

4. The low-dielectric fluorinated bismaleimide monomer according to claim 2, characterized in that, The fluorinated ether diamine comprises the following structure: Equation (3-1) Equation (3-2) Equation (3-3).

5. A low-dielectric fluorinated bismaleimide alkali-soluble resin, characterized in that, Based on the low-dielectric fluorinated bismaleimide monomer according to any one of claims 1 to 4, it is obtained by blending the following components, comprising, based on 100 parts by weight of the total weight of the components: Fluorinated bismaleimide monomer: 10-25 parts; cyanate ester: 5-20 parts; polyphenylene ether: 5-15 parts; polar solvent: 45-65 parts; initiator: 0.1-2 parts.

6. The low-dielectric fluorinated bismaleimide alkali-soluble resin according to claim 5, characterized in that, The cyanate ester includes any one of bisphenol A cyanate ester, bisphenol E cyanate ester, and phenolic cyanate ester; The polar solvent includes any one of propylene glycol methyl ether acetate, N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide; The initiator includes any one of azobisisobutyronitrile, azobisisoheptanenitrile, and dicumyl peroxide.

7. A method for preparing a low-dielectric fluorinated bismaleimide alkali-soluble resin, characterized in that, The preparation of the fluorinated bismaleimide alkali-soluble resin according to claim 5 or 6 comprises the following steps: Step 1: In a reaction vessel, add maleic anhydride, fluorinated ether diamine and polar solvent. Stir the reaction at room temperature under inert gas protection, then heat to the set temperature and react at a constant temperature to obtain a solution of fluorinated bismaleimide monomer. Step 2: When the solution obtained in Step 1 is at the set temperature, add cyanate ester to the solution and stir until it is completely dissolved to obtain a transparent solution; Step 3: When the transparent solution obtained in step 2 is at the set temperature, add polyphenylene ether and initiator to the transparent solution to react and obtain a low dielectric fluorinated bismaleimide alkali-soluble resin.

8. The method for preparing the fluorinated bismaleimide alkali-soluble resin according to claim 7, characterized in that, In step 1, the reaction is stirred at room temperature for 2-4 hours, then heated to 80-150℃ and kept at that temperature for 2-3 hours. In step 2, the set temperature of the solution is 80~110℃; In step 3, the temperature of the transparent solution is set at 120~140℃, and the reaction time is 0.5~3h.

9. A low-dielectric photoresist, characterized in that, The product comprises the following components in parts by weight: 8-15 parts of fluorinated bismaleimide alkali-soluble resin, 4-8 parts of reactive diluent, 3-6 parts of alkali-soluble acrylate monomer, 1.5-3 parts of photoinitiator, and 25-75 parts of solvent. The fluorinated bismaleimide alkali-soluble resin is the fluorinated bismaleimide alkali-soluble resin according to claim 5 or 6, or the fluorinated bismaleimide alkali-soluble resin prepared according to the preparation method according to claim 7 or 8.

10. The application of a low-dielectric fluorinated bismaleimide alkali-soluble resin, characterized in that, Application of the fluorinated bismaleimide alkali-soluble resin according to claim 5 or 6, or the fluorinated bismaleimide alkali-soluble resin prepared by the preparation method according to claim 7 or 8, in the preparation of OLED capacitive touch devices.

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