Photoresist layer stack, circuit board and method of production, electronic device

Abstract

The application discloses a photoresist layer stack, which comprises a temporary support layer and a photosensitive layer, establishes a three-dimensional orthogonal coordinate system with the surface of the temporary support layer away from the photosensitive layer as an x-axis-y-axis plane, the length direction of the temporary support layer as the x-axis, the width direction as the y-axis and the thickness direction as the z-axis, and the refractive indexes of the temporary support layer in the x-axis direction, the y-axis direction and the z-axis direction are respectively n x , n y and n z , the temporary support layer satisfies n x ≠ n y ≠ n z , and (n x -n z ) / (n y -n z )≤2. The application further discloses a preparation method of a circuit board, the circuit board and an electronic device. The photoresist layer stack has good resolution and deep curing property, and meets the high-precision requirement of the electronic circuit industry.

Description

Technical Field

[0001] This invention relates to the field of photoresist technology, specifically to a photoresist laminate, a method for preparing a circuit board, the circuit board, and electronic equipment. Background Technology

[0002] PCB (Printed Circuit Board) photoresist is a key material in the PCB manufacturing process. It is mainly divided into liquid ink-type photoresist and dry film-type photoresist. Dry film-type photoresist can be further divided into resist film and solder mask film according to its function and use. Dry film-type photoresist is usually made by uniformly coating a prepared adhesive solution onto a temporary support film, drying and cooling it, covering it with a protective film, and then rolling it up. In use, the protective film is first peeled off, the dry film-type photoresist is pressed onto the copper-clad laminate, and after exposure, the temporary support film is peeled off. Then, subsequent steps such as development are performed. The resist film also needs to be removed, while the solder mask film remains on the circuit board as a permanent protective film.

[0003] Since a temporary support film remains during exposure, its optical properties significantly impact the final exposure result. Existing temporary support films suffer from poor light transmission quality and contain a number of optical anomalous points. Internal light scattering and energy dissipation affect light collimation and the amount of light energy reaching the photoresist, thus influencing the photoresist's resolution and deep curing performance. Patent CN202180031456.2 reduces the number of defects in the temporary support film by limiting the number of foreign objects with a major diameter greater than 3 micrometers, thereby reducing the impact of optical defects on the exposure effect. However, simply reducing large optical defects does not completely improve the poor light transmission quality.

[0004] Based on this, this project developed a temporary support film with good optical performance that does not affect exposure and a photoresist laminate containing it. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and provide a temporary support layer and a photoresist stack containing it that do not affect the exposure effect.

[0006] To achieve the above objectives, the technical method adopted by the present invention is as follows:

[0007] A photoresist laminate includes a temporary support layer and a photosensitive layer. A three-dimensional orthogonal coordinate system is established with the surface of the temporary support layer away from the photosensitive layer as the x-axis and the length direction of the temporary support layer as the x-axis, the width direction as the y-axis, and the thickness direction as the z-axis. The refractive indices of the temporary support layer in the x-axis, y-axis, and z-axis directions are n, respectively. x n y n z The temporary support layer satisfies: n x ≠n y ≠nz , and (n x -n z ) / (n y -n z )≤2.

[0008] Furthermore, the haze of the temporary support layer is less than or equal to 15%, and the light transmittance is greater than or equal to 80%.

[0009] Furthermore, the tear forces of the temporary support layer in the x-axis and y-axis directions are Fpants and Ftear, respectively. x F y , 0.2≤F y / F x ≤7.

[0010] Furthermore, the temporary support layer is made of a first resin composition, which includes a main resin, inorganic fillers, and additives, wherein the weight percentage of the aromatic ring structure in the main resin is greater than or equal to 0% and less than or equal to 52% of the weight of the first resin composition.

[0011] Furthermore, the main resin is a homopolymer or copolymer; when the main resin is a copolymer, the number of monomer units is no more than three.

[0012] Furthermore, the weight ratio of the main resin to the weight of other components in the first resin composition is greater than or equal to 1.5.

[0013] Further, the main resin includes one or more of polyethylene terephthalate, polypropylene, polyethylene, ethylene-α-olefin copolymer, polyvinyl chloride, polyvinyl acetate, ethylene oxide copolymer, polyethylene naphthalate, polystyrene sulfonic acid, polyimide, polycarbonate, polymethyl methacrylate, and polybutylene terephthalate.

[0014] Another object of the present invention is to provide a method for preparing a circuit board, comprising the steps of: (1) providing a copper-clad laminate, and bonding the above-mentioned photoresist laminate with the copper-clad laminate to form a preform of "copper-clad laminate + photosensitive layer + temporary support layer"; (2) exposing the preform from one side of the temporary support layer, and then peeling off the temporary support layer; (3) developing, so that the photosensitive layer forms a target pattern; (4) etching the copper foil in the copper-clad laminate; (5) removing the target pattern formed by the photosensitive layer in step (3) to obtain a circuit board.

[0015] Another object of the present invention is to provide a circuit board comprising an insulating base film layer, a metal foil layer, and a solder resist film formed after the above-mentioned photosensitive layer has been cured.

[0016] Another object of the present invention is to provide an electronic device comprising a circuit board obtained according to the above-described preparation method or the circuit board described above.

[0017] The beneficial effects of the technical solution of the present invention include:

[0018] This invention provides a method for fabricating a photoresist laminate, a circuit board, a circuit board, and an electronic device. By limiting the differences in refractive properties at different angles and the relationship between refractive index values ​​in the temporary support layer, the influence of the presence of the temporary support layer on the exposure effect is reduced, thereby improving the resolution and deep curing properties of the photosensitive layer. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will be further described in detail below with reference to specific embodiments.

[0020] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the ordinary meaning that can be understood by one of skill in the art.

[0021] As analyzed in the background section, dry film photoresists are typically exposed from the temporary support layer side. After exposure, the temporary support layer is peeled off, followed by development and other processes. Therefore, the optical properties of the temporary support layer have a significant impact on the exposure effect. Existing films suitable for temporary support layers generally have a certain number of optical anomalous points, resulting in poor light transmittance and altered light propagation paths, which in turn affect the photopolymerization effect, resolution, pattern accuracy, and deep curing performance of the photosensitive layer. Furthermore, contamination from impurities during the manufacturing process and poor light transmittance and high haze due to limitations in current fabrication techniques also profoundly affect the performance and characteristics of photoresist laminates. Existing technologies cannot meet the increasingly stringent precision requirements of the rapidly developing electronics industry for process materials such as solder resists and photoresist films. To address this issue, this invention provides a photoresist laminate, a circuit board and its fabrication method, and an electronic device.

[0022] The forming methods for the film used in the temporary support layer are nothing more than stretching, extrusion, casting, and calendering, among which stretching is the most commonly used. During the forming process, as the film layer is subjected to stress, there will be orientation or even crystallization of polymer chains, stretching or even dimensional changes in the film layer (such as a decrease in thickness), generation of internal stress, and displacement and redistribution of inorganic fillers. The external manifestation is the anisotropy of the film layer, which ultimately affects light transmittance, haze, and light transmission quality. When the film layer is oriented in one or more directions, a mismatch in refractive index occurs along one or more axes. The greater the difference in refractive index in each axis, the stronger the scattering of light in that direction, and the easier it is to cause phenomena such as image distortion. The direction of light propagation changes, and there is a deviation between the actual position of the photosensitive layer where the photocuring reaction occurs and the position of the target pattern. Light scattering in the film layer, longer propagation path, and more energy dissipation affect the amount of light reaching the depth of the photosensitive layer. The above factors together affect the deep curing and resolution of the photosensitive layer. Therefore, by adjusting the amount of refractive index mismatch along a specific axis within a certain range, the degree of light scattering can be effectively controlled, allowing as much light as possible to be mirror-transmitted through the temporary support layer, thereby improving the light transmission quality of the temporary support layer and, to some extent, solving the problem of poor exposure effect of the photosensitive layer caused by poor light transmission quality of the temporary support layer.

[0023] In a typical embodiment of this application, a photoresist laminate is provided, comprising a temporary support layer and a photosensitive layer. A three-dimensional orthogonal coordinate system is established with the surface of the temporary support layer away from the photosensitive layer as the x-axis and the length direction of the temporary support layer as the x-axis, the width direction as the y-axis, and the thickness direction as the z-axis. In actual production, the photoresist laminate is generally produced by coating a photosensitive layer with adhesive onto a temporary support layer of a certain width, drying the solvent, and then winding it up to exist, transport, and store it in roll form. Downstream manufacturers (such as PCB manufacturers) unwind the roll and cut it to obtain a rectangular photoresist laminate before bonding and exposing it. Unless otherwise specified, the length direction (x-axis direction) generally refers to the original winding / unwinding direction, and the width direction (y-axis direction) refers to the width direction of the original film roll. The refractive indices of the temporary support layer in the x-axis, y-axis, and z-axis directions are n, n, and n, respectively. x n y n z The temporary support layer satisfies: n x ≠n y ≠n z , and (n x -n z ) / (n y -n z )≤2, preferred (n) x -n z ) / (n y -n z If )≤1.5, further optimization (n)x -n z ) / (n y -n z ) < 1, more preferably (n) x -n z ) / (n y -n z ≤0.5. The above refractive index value can be measured using an Abbe refractometer or prism coupler. Generally, the refractive index of the temporary support layer in the ultraviolet band is tested. In particular, depending on actual production needs, the test wavelength range generally corresponds to the exposure wavelength range of the exposure machine. Specifically, the test wavelength range is 300-405nm, more specifically 365-405nm, or one or more specific wavelengths of 365nm, 385nm, or 405nm can be selected.

[0024] In a typical embodiment of this application, the haze of the temporary support layer is less than or equal to 15%, and the transmittance is greater than or equal to 80%. Haze refers to the percentage of transmitted light intensity at an angle greater than 2.5° from the incident light to the total transmitted light intensity. Higher haze means a decrease in the film's transparency, especially its imaging quality. Haze and transmittance are two concepts; a material with high haze does not necessarily have low transmittance. A film with high haze and high transmittance can achieve high transmittance and excellent concealment. Based on the actual production needs of this product, the temporary support layer needs to have low haze and high transmittance. Therefore, the haze of the temporary support layer is limited to less than or equal to 15%, and the transmittance is greater than or equal to 80%. Preferably, the haze is less than or equal to 10%, more preferably less than or equal to 8%. Preferably, the transmittance is greater than or equal to 85%, further preferably greater than or equal to 87%, and more preferably greater than or equal to 90%.

[0025] In a typical embodiment of this application, the trouser-shaped tear forces of the temporary support layer in the x-axis direction and the y-axis direction are F, respectively. x F y , 0.2≤F y / F x ≤7, preferably 0.5≤F y / F x ≤5, further optimization is 1≤F y / F x ≤2. The difference in tear strength along different axes is an important parameter reflecting the anisotropy of the film layer. It can usually be adjusted by modifying the type of raw material, the stretch ratio during manufacturing, thickness, tensile strength, and heat shrinkage rate of the film, as well as the differences in tear strength along different axes. F y / F xThe closer the ratio is to 1, the smaller the performance difference and anisotropy of the temporary support layer in the x-axis and y-axis directions. Due to process limitations, the polymer chains in the temporary support layer are generally oriented along the x-axis (i.e., the winding or unwinding direction). Therefore, tearing in the x-axis direction mainly overcomes van der Waals forces between molecular chains, while tearing in the y-axis direction requires overcoming covalent bond forces from polymer chain breakage and van der Waals forces between molecular chains. Therefore, F... y Generally, greater than or equal to F x .

[0026] In a typical embodiment of this application, the temporary support layer is made of a first resin composition, which includes a main resin, inorganic fillers, and additives. The main resin, as the primary component of the first resin composition, fundamentally determines the mechanical and optical properties of the temporary support layer. Films containing aromatic ring structures such as benzene or naphthalene rings in the molecular chain of the main resin generally exhibit more severe birefringence than films without aromatic ring structures in the molecular chain of the main resin. Furthermore, aromatic ring structures such as benzene rings are easily oxidized, causing the film to yellow, thus affecting light transmittance and hindering long-term storage. Therefore, the weight percentage of aromatic ring structures in the main resin of the first resin composition is limited to greater than or equal to 0% and less than or equal to 52%, preferably greater than or equal to 0% and less than or equal to 45%, more preferably greater than or equal to 0% and less than or equal to 40%, and even more preferably greater than or equal to 0% and less than or equal to 35%.

[0027] In a typical embodiment of this application, the main resin is a homopolymer or a copolymer. When the main resin is a copolymer, since the refractive indices of different monomer units are different, the proportion of each monomer unit must be adjusted appropriately. Otherwise, the birefringence phenomenon will be very serious. The more types of monomer units there are, the more difficult it is to achieve the ideal light transmission effect by adjusting the proportion. Therefore, the main resin is preferably a homopolymer, or preferably a copolymer with no more than 3 types of monomer units, and more preferably no more than 2 types.

[0028] In a typical embodiment of this application, the weight ratio of the main resin to the weight of other components in the first resin composition is greater than or equal to 1.5. The raw materials (first resin composition) used to prepare the temporary support layer include the main resin, inorganic fillers, additives, etc. The main resin is an organic polymer, the additives are generally small organic molecules, and the inorganic fillers are inorganic components. There are certain compatibility issues between organic and inorganic substances, and between organic macromolecules and small organic molecules, and the refractive indices of each component are different. Therefore, additives and inorganic fillers are generally not added or are added in small quantities in optical films.

[0029] In a typical embodiment of this application, the main resin includes one or more of polyethylene terephthalate, polypropylene, polyethylene, ethylene-α-olefin copolymer, polyvinyl chloride, polyvinyl acetate, ethylene oxide copolymer, polyethylene naphthalate, polystyrene sulfonic acid, polyimide, polycarbonate, polymethyl methacrylate, and polybutylene terephthalate. The main resin may also be a modified polymer based on the above polymers, after grafting or copolymerization modification. Among these, bisphenol A type polycarbonate films and polystyrene sulfonic acid films exhibit more birefringence and scatter more transmitted light compared to other films, and are not preferred optical films. Polyvinyl chloride (PVC) films have excellent flexibility and transparency, but on the one hand, they are prone to the slow release of plasticizers and dust attraction, which causes a rapid decrease in light transmittance and shortens their service life. On the other hand, PVC films are too soft and have poor support. In addition, in order to prevent the photoresist laminate from curing prematurely due to heat during storage, it is generally stored at low temperature. However, PVC films have poor low-temperature resistance and become brittle and hard at low temperatures, affecting the storage performance of the photoresist laminate. The benzene ring and imide ring functional groups in the polyimide molecule are both luminescent groups. Due to the π-π* transitions of electrons on the conjugated benzene ring / double bond, they exhibit color in the visible light region. Depending on the polyimide molecular chain structure and the ratio of benzene ring to imide functional groups, the energy of the π-π* transition varies, resulting in different colors such as yellow, tan, and brown for polyimide films. These colors are inherent to the polyimide material and are difficult to remove except by adjusting the molecular chain structure; conventional methods can only achieve a lighter color. Currently, a small number of transparent and colorless polyimide films exist on the market, but their preparation requires stringent conditions. Considering optical properties, heat resistance, mechanical strength, operability, and durability, polyester or polyolefin is preferred as the main resin for the temporary support layer.

[0030] In a typical embodiment of this application, the inorganic filler includes calcium oxide, silicon dioxide, boehmite, barium sulfate, calcium titanate, boron nitride, aluminum nitride, silicon carbide, aluminum oxide, magnesium oxide, kaolin, montmorillonite, talc, zirconium oxide, zinc oxide, clay, mica powder, asbestos powder, calcium carbonate, zeolite, aluminum silicate, magnesium silicate, etc.

[0031] In a typical embodiment of this application, the additives are selected from those commonly used in the preparation of polymer films, including catalysts, stabilizers, ether inhibitors, flame retardants, slip agents, colorants, surfactants, antioxidants, plasticizers, antistatic agents, lubricants, toughening agents, compatibilizers, and anti-sticking agents. The catalysts include titanium-based catalysts, antimony-based catalysts, acidic catalysts such as sulfuric acid, phosphoric acid, and zinc chloride, solubilizing catalysts such as phenol and methanol, and metal-free catalysts such as amide salts. The flame retardants include phosphorus-based flame retardants, silicon-based flame retardants, halogen-based flame retardants, nitrogen-based flame retardants, and other flame retardants such as magnesium hydroxide, aluminum hydroxide, aluminum trihydrate, antimony trioxide, and antimony pentoxide. The antioxidants include tetra[methylene-3-(3',5′-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3',5′-di-tert-butyl-4′-hydroxyphenyl)propionate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, tris(2,4-di-tert-butylphenyl)phosphite, and tris(nonylphenyl)phosphite. Distearate pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4′-biphenylene diphosphite, 4,4′-thiodi-(6-tert-butyl-m-cresol), 2,2′-methylenedi-(4-methyl-6-tert-butylbutylphenol), octadecyl 3,5-di-tert-butyl-4-hydroxyhydrogenated cinnamate, bis-(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, phosphonic acid ((3,5-di(1, 1-Dimethylethyl)-4-hydroxyphenyl)methyl)-(octadecyl) ester, N,N'-1,6-hexanediylbis(3,5-di(1,1-dimethyl)-4-hydroxyphenylpropionamide, aromatic amines, alkylated diphenylamine, sulfur-containing bisphenols, alkylated phenyl-8-naphthylamine, fluorophosphonites, 2,2'-ethylenedi(4,6-di-tert-butylphenyl)fluorophosphite, butylated hydroxytoluene, di(O-ethyl(3 The components include calcium (3,5-di-tert-butyl-4-hydroxybenzyl)phosphate, tetra(methylene(3,5-di-tert-butyl-4-hydroxymethylcinnamate))methane, octadecyl 3,5-di-tert-butyl-4-hydroxymethylcinnamate, hindered bisphenols, high molecular weight hindered phenols, and hindered phenolic amines. The lubricant includes calcium stearate, zinc stearate, copper stearate, cobalt stearate, neomolybdenum dodecanoate, and ruthenium acetylacetonate. The compatibilizer includes silane coupling agents.

[0032] In a typical embodiment of this application, the first resin composition comprises, by weight parts, 50-99.9 parts of a main resin, 0-20 parts of an inorganic filler, and 0-45 parts of an additive.

[0033] In a typical embodiment of this application, the first resin composition further includes a solvent. The solvent includes N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyl sulfoxide, deionized water, styrene, perchloroethylene, trichloroethylene, chloroform, carbon tetrachloride, tetrachloroethylene, trichloropropane, dichloroethane, ethylene glycol ether, triethanolamine, benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, methylcyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, methanol, ethanol, isopropanol, diethyl ether, propylene oxide, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl butyl ketone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, acetonitrile, pyridine, phenol, etc.

[0034] In a typical embodiment of this application, the thickness of the temporary support layer is 8-45 micrometers, and the thickness of the photosensitive layer is 10-60 micrometers.

[0035] In a typical embodiment of this application, the photoresist laminate further includes a protective layer located on the surface of the photosensitive layer away from the temporary support layer. The protective layer is selected from polyethylene terephthalate film, polypropylene film, polyethylene film, polyvinyl chloride film, polyvinyl acetate film, ethylene oxide copolymer film, polyethylene naphthalate film, polystyrene sulfonic acid film, polyimide film, polycarbonate film, polymethyl methacrylate film, polybutylene terephthalate film, and composite films made from a mixture of the above-mentioned main resins, or films formed by stacking one or more of these films.

[0036] In a typical embodiment of this application, the photosensitive layer is formed from a second resin composition. The second resin composition includes an alkali-soluble resin, an active monomer, and a photoinitiator. From the perspectives of developability, flowability, operability, and flexibility, the second resin composition preferably includes 100 parts by weight of an alkali-soluble resin, 10-60 parts by weight of an active monomer, and 0-7 parts by weight of a photoinitiator, based on parts by weight.

[0037] The alkali-soluble resin can be selected from conventional alkali-soluble resins in the prior art, including acrylic resins and / or alkali-soluble polyimide resins; the monomer units of the acrylic resin are selected from itaconic acid, crotonic acid, acrylic acid, methacrylic acid, maleic acid half ester, maleic acid, fumaric acid, vinyl acetic acid and its anhydrides, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, isooctyl methacrylate, lauryl methacrylate, octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc. The resin comprises any one or more of the following: 4-hydroxybutyl ester, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, (meth)acrylonitrile, (meth)acrylate glycidyl acrylate, N,N-dimethyl(meth)acrylate ethyl ester, N,N-diethyl(meth)acrylate ethyl ester, N,N-dimethyl(meth)acrylate propyl ester, N,N-diethyl(meth)acrylate propyl ester, N,N-dimethyl(meth)acrylate butyl ester, N,N-diethyl(meth)acrylate butyl ester, (meth)acrylamide, N-hydroxymethylacrylamide, N-butoxymethylacrylamide, styrene, (meth)acrylate benzyl ester, phenoxyethyl(meth)acrylate, and (alkoxylated)nonylphenol(meth)acrylate. The acid value of the alkali-soluble resin is 10-200 mg KOH / g, and the weight-average molecular weight of the alkali-soluble resin is 2000-150000.

[0038] The active monomer is a monomer containing an olefinically unsaturated group, and can also be selected from conventional photopolymerizable monomers, including but not limited to monofunctional (meth)acrylates, difunctional (meth)acrylates, trifunctional (meth)acrylates, or polyfunctional (meth)acrylates. Specifically, examples include (ethoxy)phenol (meth)acrylate, stearate acrylate, ethoxy(propoxy)nonylphenol (meth)acrylate, ethoxy(propoxy)tetrahydrofurfuryl (meth)acrylate, and 1,6-hexanediol dimethyl ether. Acrylates, tricyclodecanediethanol diacrylate, dioxanediol diacrylate, ethoxylated (propoxylated)bisphenol A di(meth)acrylate, polyethylene glycol (400) diacrylate, polypropylene glycol (600) diacrylate, ethoxylated (propoxylated)trimethylolpropane tri(meth)acrylate, pentaerythritol triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, dipentaerythritol hexaacrylate, ethoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate are any one or more of these.

[0039] The photoinitiator is selected from conventional photopolymerization initiators and photosensitizers, such as diacetic titanium dioxide, acetophenone, oxime esters, phosphine oxide, anthrone, benzoyl ether, benzophenone, anthraquinone, thioxanthone compounds, hexaaryl diimidazole compounds, acridine compounds, etc., including but not limited to 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, 2-(acetoxyiminomethyl)thioxanth-9-one, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] ethyl ketone 1-(O-acetyl oxime), 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1- One or more of the following: [4-(2-hydroxy)-phenyl]-3-hydroxy-2-methyl-1-propanone-1-one, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-methyl-1-(4-methylthiophenyl)-2-morphenyl-1-propanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, diethyl 2,4-oxalate, 2,4-diethylthiazolinone, 2-isopropylthioxanthanone, 2-ethylanthanone, 2,4-diethylthioxanthanone, and benzophenone.

[0040] In another typical embodiment of this application, the second resin composition further includes a curing agent. The curing agent is selected from one or more of epoxy resins, isocyanates or isocyanurates, or triazine compounds; the epoxy resin is selected from bisphenol-type epoxy resins, biphenyl-type epoxy resins, phenolic epoxy resins, epoxy resins containing a naphthalene ring, and alicyclic epoxy resins; the bisphenol-type epoxy resin is selected from bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins; the phenolic epoxy resin is selected from phenolic phenolic epoxy resins and phenolic epoxy resins. The epoxy equivalent of the epoxy resin is 50–350 g / eq, and the softening point is 40–150°C. Preferably, the second resin composition includes 5–20 parts by weight of the curing agent, calculated based on 100 parts by weight of alkali-soluble resin.

[0041] In another typical embodiment of this application, the second resin composition further includes fillers and additives. The fillers include colored fillers and system fillers. Specifically, the colored fillers are selected from organic or inorganic fillers, including but not limited to: red fillers, such as monoazo, diazo, azo lake, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, quinacridone, etc.; blue fillers, such as phthalocyanine, anthraquinone, etc.; yellow fillers, such as monoazo, diazo, condensed azo, benzimidazolone, isoindoline, anthraquinone, etc.; black fillers, such as carbon black, graphite, iron oxide, titanium black, iron oxide, anthraquinone, cobalt oxide, copper oxide, manganese, antimony oxide, nickel oxide, perylene, aniline, molybdenum sulfide, bismuth sulfide, etc.; white fillers, such as rutile or anatase titanium oxide, barium sulfate, etc.; orange, green, and purple fillers can also be added as needed. Other fillers include silica, talc, barium sulfate, calcium carbonate, zinc oxide, etc. The additives include color developers, plasticizers, defoamers, polymerization inhibitors, and antioxidants. The color developers are selected from one or more of pentyl bromide, ethylene dibromide, benzyl bromide, dibromomethane, tribromomethylphenyl sulfone, trichloroacetamide, pentyl iodide, and chloroethane. The plasticizers are selected from phthalic acid compounds or sulfonamide compounds, preferably from one or more of diethyl phthalate, diphenyl phthalate, and p-toluenesulfonamide. The defoamers are selected from one or more of non-silicone defoamers, polyether defoamers, organosilicon defoamers, and polyether-modified organosilicon defoamers. The polymerization inhibitors are selected from one or more of p-methoxyphenol, hydroquinone, pyrogallol, tert-butylcatechol, and N-nitrosophenylhydroxylamine aluminum salt. The antioxidants are selected from one or more of amine antioxidants, phenolic antioxidants, thioester-assisted antioxidants, phosphite-assisted antioxidants, and thioether-assisted antioxidants. Based on 100 parts by weight of alkali-soluble resin, the second resin composition preferably includes 5-20 parts by weight of filler and additives.

[0042] In a typical embodiment of this application, the present invention provides a method for preparing a circuit board, comprising the following steps: (1) providing a copper-clad laminate, and bonding the above-mentioned photoresist laminate to the copper-clad laminate to form a preparatory body of "copper-clad laminate + photosensitive layer + temporary support layer"; (2) exposing the preparatory body from one side of the temporary support layer, and then peeling off the temporary support layer; (3) developing, so that the photosensitive layer forms a target pattern; (4) etching the copper foil in the copper-clad laminate; (5) removing the target pattern formed by the photosensitive layer in step (3) to obtain the circuit board. The above bonding is generally carried out by vacuum laminating machine or hot press roller pressing; the above exposure equipment is a laser exposure machine or an ultraviolet exposure machine, and the light source can be selected from high-pressure mercury lamp, UV-LED lamp, KrF excimer laser, Ar ion laser, YAG laser, etc., with an exposure wavelength of 365-405nm; the development is generally carried out by alkaline solution such as sodium hydroxide aqueous solution or sodium carbonate aqueous solution. The photoresist laminate is a process material for pattern transfer in the above-mentioned circuit board preparation process, and acts as a resist.

[0043] In another typical embodiment of this application, the present invention provides a circuit board, the circuit board comprising an insulating base film layer, a metal foil layer and a solder resist film formed after the above-mentioned photosensitive layer is cured.

[0044] In a typical embodiment of this application, the present invention provides an electronic device comprising a circuit board obtained according to the above-described preparation method or the circuit board described above. The electronic device is not particularly limited and may include LED direct-view modules, LED backlights, communication devices such as computers and mobile phones, and optoelectronic glass curtain walls, etc.

[0045] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0046] 1. Set up the examples and comparative examples according to Table 1-1 / Table 1-2 / Table 1-3.

[0047] Table 1-1: Comparative Examples (Photosensitive Layer Formulation by Parts by Mass)

[0048]

[0049] Table 1-2: Comparative Examples (Photosensitive Layer Formulation by Parts by Mass)

[0050]

[0051]

[0052] Table 1-3: Comparative Examples (Photosensitive Layer Formulation by Parts by Mass)

[0053]

[0054] illustrate:

[0055] A-1: Acid-modified epoxy acrylate resin (Nippon Kayaku ZFR-1401H, bisphenol F type, solid content 60%, acid value 98mgKOH / g);

[0056] A-2: Acrylic resin (Cyclomer P(ACA)Z250, solid content 45%, acid value 70mgKOH / g); B-1: Stearate acrylate (Osaka Organic Chemicals, double bond equivalent 325g / mol);

[0057] B-2: Ethoxynonylphenol acrylate (Kedi Chemical LM158, double bond equivalent 450 g / mol);

[0058] C-1: 2,2',4-Tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4',5'-diphenyl-1,1'-diimidazole (Changzhou Qiangli Electronics);

[0059] C-2: 9-Phenylacetidine (Shanghai Tixiai Chemical Co., Ltd.);

[0060] D-1: Bisphenol A type epoxy resin (Japanese epoxy resin JER828, epoxy equivalent 184-194g / eq);

[0061] The PET film used in Comparative Example 1 was KIMOTO N60-250 high haze PET film from Japan;

[0062] The BOPP film used in Comparative Example 2 was sourced from Hechuang Innovation MFa BOPP matte film.

[0063] 2. Preparation of photoresist laminate.

[0064] On the production line, the above-mentioned second resin composition liquid is uniformly coated on a temporary support layer (10 μm thick) and dried through a channel at a temperature of 90°C until the solvent content is 0.1 wt% to 0.3 wt%, forming a photosensitive layer; a PE film (20 μm) is laminated as a protective layer on the side of the photosensitive layer away from the temporary support layer, thereby forming a photoresist laminate.

[0065] The following describes the sample preparation method, sample evaluation method, and evaluation results of the embodiments and comparative examples.

[0066] [Screen protector]

[0067] The copper-clad laminate is polished using a grinding machine, washed with water, and dried to obtain a bright and fresh copper surface. The laminating machine is set with a pressure roller temperature of 110℃, a conveying speed of 1.5m / min, and heat lamination under standard pressure.

[0068]

exposure

[0069] Exposure was performed using a Chih Sheng Technology M-522 exposure machine, and photosensitivity was tested using a Stouffer 21-step exposure scale.

[0070]

development

[0071] The temporary support layer was peeled off. The film linewidth / spacing was selected and gradually increased from 10 μm to 100 μm; the developer was a 1% wt sodium carbonate aqueous solution, the developing temperature was 30℃, the developing pressure was 1.8 bar, the developing speed was 1.5 m / min, and the developing machine was a Yuansu Technology XY-430. The minimum developing time was defined as the minimum time required for the unexposed photosensitive layer to completely dissolve.

[0072] [Matching of refractive indices along different axes]

[0073] The refractive index of the temporary support layer along different axes was determined using an ATAGO NAR-3T Abbe refractometer (Japan), and (n) was calculated. x -n z ) / (n y -n z ).

[0074] [Haze, Light Transmittance]

[0075] The haze and transmittance of the temporary support layer were measured using a TH-110 haze meter. The test method was in accordance with ASTM D1003-2021, "Standard Test Methods for Haze and Transmittance of Transparent Plastics".

[0076] [Tear Resistance of Pants]

[0077] Tensile strength was measured using a Shimadzu EZ-SX tensile tester, and the test method was in accordance with JIS-K-7128-1-1998 "Determination of tear resistance of plastic films and sheets".

[0078] [Analysis]

[0079] A photosensitive layer is laminated onto a copper-clad laminate using heated rollers. Here, a mask with a wiring pattern having a 1:1 (10-100 μm) width ratio of exposed and unexposed portions is exposed. After development for 1.5 times the development removal time, the pattern is observed using a magnifying glass. The resolution is evaluated by the minimum line width that can completely remove the unexposed portions without distortion, defects, or remaining lines. The smaller this value, the better the resolution.

[0080] [Deep curing properties]

[0081] 1. Take a photoresist laminate and a copper-clad laminate with dimensions of 10cm×10cm respectively. (After peeling off the protective layer) Place the photosensitive layer of the photoresist laminate with the copper surface of the copper-clad laminate facing it. Attach the laminate to the copper-clad laminate at 70℃ and 4 kg pressure, and perform exposure, development, and thermal curing. Remove the temporary support layer to form a test sample. Immerse the test sample in a gold-plating solution at 85℃ for 30s. Use a cross-cutting tool to create 10×10 square grids of 1mm×1mm size on the surface of the photosensitive layer of the test sample, ensuring all grid gaps expose the copper surface. Remove debris from the grid areas with a brush. Attach 3M 600 tape to the grid areas and press to remove air bubbles between the tape and the grid. Tear the tape off the test sample roughly perpendicularly and record the number of squares (n) that peeled off.

[0082] 2. The cross-section of the developed photosensitive layer was observed using a Phenom Prox scanning electron microscope to evaluate the penetration (lateral etching) of the developer: A: No lateral etching occurred; B: Lateral etching was less than 5 micrometers; C: Lateral etching was 5-10 micrometers; D: Lateral etching was more than 10 micrometers.

[0083] [Evaluation Results]

[0084] The evaluation results of the examples and comparative examples are shown in Table 2. All data were measured under the condition of 7 exposure frames.

[0085] Table 2: Evaluation Results of Examples and Comparative Examples

[0086] Example 1 Example 2 Example 3 Example 4 Example 5 Resolution / micrometer 40 45 40 40 45 Number of squares n 0 2 1 0 2 Lateral erosion A A A A A Example 6 Example 7 Example 8 Example 9 Example 10 Resolution / micrometer 40 45 45 40 50 Number of squares n 2 2 1 1 3 Lateral erosion B B A A B Example 11 Example 12 Example 13 Comparative Example 1 Comparative Example 2 Resolution / micrometer 45 50 40 55 60 Number of squares n 2 4 0 8 12 Lateral erosion B B A C D

[0087] As shown in Table 2, the resolution and deep curing properties of Examples 1-13 are within the acceptable range and are superior to Comparative Examples 1 and 2. Specifically, compared with Example 1, Example 3 has an increased proportion of inorganic fillers and additives in the first resin composition. Due to compatibility issues between organic and inorganic substances, and between organic macromolecules and organic small molecules, and the different refractive indices of each component, Example 3 exhibits square-shaped peeling and poor deep curing properties. In Example 6, the weight percentage of the main resin is close to that of the inorganic fillers and additives. In this case, the effect of a small amount of inorganic fillers and additives on the refractive index matching and haze of the temporary support layer should not be considered. Instead, the destruction of the crystallinity of the main resin by a large number of organic small molecules and inorganic fillers should be considered. Therefore, Example 6 only shows a decrease in transmittance compared to Example 1. Compared with Examples 1, 2, and 11, the number of monomer units increases, making it more difficult to adjust the proportion of each monomer unit to reduce the refractive index mismatch. Therefore, the lateral etching phenomenon in Example 11 is more severe. Example 2 has a higher proportion of aromatic structures than Example 1, resulting in decreased light transmittance, which leads to poorer resolution of the photosensitive layer and a greater number of squares falling off in the grid method.

[0088] In summary, the temporary support layer of the present invention has better light transmission quality, and the photoresist laminate using the present invention exhibits excellent resolution and deep curing properties during use.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A photoresist laminate, characterized in that, The photoresist stack includes a temporary support layer and a photosensitive layer. A three-dimensional orthogonal coordinate system is established with the surface of the temporary support layer away from the photosensitive layer as the x-axis-y-axis plane and the length direction of the temporary support layer as the x-axis, the width direction as the y-axis, and the thickness direction as the z-axis. The refractive indices of the temporary support layer in the x-axis, y-axis, and z-axis directions are n, respectively. x n y n z The temporary support layer satisfies: n x ≠n y ≠n z , and (n x -n z ) / (n y -n z )≤2.

2. The photoresist laminate according to claim 1, characterized in that, The temporary support layer has a haze of less than or equal to 15% and a light transmittance of greater than or equal to 80%.

3. The photoresist laminate according to claim 1, characterized in that, The temporary support layer has trouser tear forces F in the x-axis and y-axis directions, respectively. x F y , 0.2≤F y / F x ≤7.

4. The photoresist laminate according to claim 1, characterized in that, The temporary support layer is made of a first resin composition, which includes a main resin, inorganic fillers, and additives, wherein the weight percentage of the aromatic ring structure in the main resin is greater than or equal to 0% and less than or equal to 52% of the weight of the first resin composition.

5. The photoresist laminate according to claim 4, characterized in that, The main resin is a homopolymer or copolymer; when the main resin is a copolymer, the number of monomer units is no more than 3.

6. The photoresist laminate according to claim 4, characterized in that, The weight ratio of the main resin to the weight of other components in the first resin composition is greater than or equal to 1.

5.

7. The photoresist laminate according to claim 4, characterized in that, The main resin includes one or more of polyethylene terephthalate, polypropylene, polyethylene, ethylene-α-olefin copolymer, polyvinyl chloride, polyvinyl acetate, ethylene oxide copolymer, polyethylene naphthalate, polystyrene sulfonic acid, polyimide, polycarbonate, polymethyl methacrylate, and polybutylene terephthalate.

8. A method for manufacturing a circuit board, characterized in that, The steps include: (1) providing a copper-clad laminate, and bonding the photoresist laminate according to any one of claims 1-7 to the copper-clad laminate to form a preform of "copper-clad laminate + photosensitive layer + temporary support layer"; (2) Expose the preform from one side of the temporary support layer, and then peel off the temporary support layer; (3) Develop the photosensitive layer to form the target pattern; (4) Etch the copper foil in the copper-clad laminate; (5) Removal Steps (3) The target pattern formed by the photosensitive layer is used to obtain the circuit board.

9. A circuit board, characterized in that, The circuit board includes an insulating base film layer, a metal foil layer, and a solder resist film formed after the photosensitive layer according to any one of claims 1-7 has been cured.

10. An electronic device, characterized in that, The electronic device includes a circuit board obtained by the preparation method according to claim 8 or a circuit board according to claim 9.

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