Ink-jet printing photo-curing material for PCB drilling and preparation method and application of ink-jet printing photo-curing material

Abstract

The invention discloses an ink-jet printing photocuring material for PCB drilling and a preparation method and application thereof, and the photocuring material comprises the following components in parts by mass: 50-98 parts of a monofunctional monomer, 0-15 parts of a monomer with more than bifunctionality, 0-50 parts of a nonionic water-soluble polymer, 1-50 parts of acidic resin, 0.1-10 parts of a photoinitiator and 0-15 parts of nano powder, and 0.1-10 parts of an auxiliary agent. The photocuring material disclosed by the invention can be used for drilling a PCB (Printed Circuit Board), and is selectively printed at a position, which needs to be drilled, of the PCB in an ink-jet printing manner, so that the drilling yield and quality are ensured; the ink-jet printer is used for an ink-jet printing mode of PCB drilling, operation is easy, energy is saved, cost is greatly saved through a selective printing mode, and the ink-jet printer is harmless to a human body; and after drilling is completed, the PCB can be easily removed in water, water-based liquid or alkaline film stripping liquid, and the subsequent process of the target PCB is not affected.

Description

Technical Field

[0001] The invention belongs to the technical field of photocurable materials, and in particular relates to an inkjet printing photocurable material for PCB drilling, a preparation method and an application thereof. Background Art

[0002] PCB, or printed circuit board, is one of the important components of the electronics industry. It appears in almost every electronic device. The electronic parts in electronic devices are embedded on PCBs of various sizes. The main function of PCB is to connect various electronic components to form a predetermined circuit and play the role of relay transmission. As one of the core components of electronic products, PCB circuit boards are constantly developing in the direction of high precision and cutting-edge. In order to achieve an increase in the density of fixed volume circuits, the electronics manufacturing industry has developed high-density interconnected printed circuit boards. Through the superposition of multiple layers of circuit boards, they are isolated from each other by insulating layers, and holes are drilled between the insulating layers, and then the holes are plated with metal to achieve line conduction between layers of circuits, thereby greatly improving the line density.

[0003] Laser drilling directly on the surface of the circuit board is very likely to produce copper chips, which will affect the accuracy of drilling, and this method can only be used on multi-layer circuits with fewer layers. For multi-layer boards with more layers, only a drill needle can be used, but currently, multi-layer boards with more layers are almost all drilled directly, and the copper surface has no auxiliary coating, which seriously affects the accuracy of drilling. In order to solve the current problem, drilling ink has emerged. The main function of drilling ink is that it can solidify on the copper surface to form a temporary protective coating, which protects the surface of the PCB circuit board during the drilling process, effectively inhibits the generation of copper chips, and thus improves the drilling accuracy, improves the quality of the hole wall, reduces the wear of the drill needle, and inhibits the upper flash.

[0004] CN116042037B discloses a temporary protective coating for PCB drilling that can be cured under UV light to form a temporary protective coating, which protects the surface of the PCB circuit board during the drilling process, effectively suppresses the generation of copper chips, and thus improves the drilling accuracy. After the cured coating is soaked in water at room temperature for 1-2 minutes, the water-absorbing microbeads added therein can expand strongly, so that the temporary protective coating automatically falls off from the surface of the substrate. However, the temporary protective coating has a complex composition and is not suitable for inkjet printing, and the film-fading process is likely to affect the subsequent process of the target PCB board. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a photocurable material for inkjet printing for PCB drilling, which can utilize the characteristics of inkjet printing to selectively print at the position where the PCB needs to be drilled, thereby ensuring the drilling yield and quality; after the drilling is completed, it can be easily removed in water, aqueous liquid or alkaline film stripping liquid without affecting the subsequent process of the target PCB board. At the same time, the inkjet printing method for PCB drilling is simple to operate, energy-saving, greatly saves costs through selective printing, and is harmless to the human body.

[0006] Another object of the present invention is to provide a method for preparing the inkjet-printed photocurable material for PCB drilling.

[0007] Another object of the present invention is to provide an application of the inkjet-printed photocurable material for PCB drilling.

[0008] In order to achieve the above invention object, the present invention adopts the following technical solution:

[0009] An inkjet printing photocurable material for PCB drilling comprises the following components in parts by weight:

[0010] 50-98 parts of monofunctional monomer, 0-15 parts of difunctional or higher monomer, 0-50 parts of nonionic water-soluble polymer, 1-50 parts of acidic resin, 0.1-10 parts of photoinitiator, 0-15 parts of nano powder, 0.1-10 parts of auxiliary agent;

[0011] Wherein, the acidic resin is selected from one or more polymer resins having acidic functional groups, and the acid value of the acidic resin is in the range of 50-250 mgKOH / g.

[0012] In some specific embodiments, the monofunctional monomer is selected from one or more of a monofunctional acrylate monomer, a monofunctional acrylamide derivative monomer or a monofunctional vinyl monomer;

[0013] In some specific embodiments, the monomer having bifunctionality or higher is selected from one or more of bifunctional acrylate monomers and multifunctional acrylate monomers;

[0014] In some specific embodiments, the photoinitiator is selected from free radical photoinitiators.

[0015] In some specific embodiments, the nonionic water-soluble polymer is selected from one or more of polyvinyl alcohol, polyethylene glycol, polyacrylamide, polypyrrolidone, polyacryloylmorpholine or methylcellulose.

[0016] In some specific embodiments, the nano powder is selected from one or more of nano organic pigments, nano titanium dioxide, nano silicon dioxide, and nano aluminum oxide; preferably, the particle size range is 100-800 nm.

[0017] In some specific embodiments, the auxiliary agent is selected from one or more of an inhibitor, a defoaming agent or a leveling agent.

[0018] In some specific embodiments, the photocurable material is liquid at room temperature;

[0019] Preferably, the photocurable material has a viscosity of 10-150 cps and a surface tension of 20-40 dyn at room temperature, and a viscosity of 8-14 cps and a surface tension of 20-38 dyn at the injection temperature, wherein the injection temperature is not lower than room temperature;

[0020] In some preferred embodiments, the photocurable material has a hardness of H or above after curing, and can be rapidly delaminated in water, aqueous liquid or alkaline delamping liquid;

[0021] In some more preferred embodiments, when the photocurable material is used to coat a film layer with a thickness of 15 μm, the time required for film stripping by immersion in water, aqueous liquid or alkaline film stripping solution is less than or equal to 5 minutes.

[0022] On the other hand, the method for preparing the aforementioned inkjet printing photocurable material for PCB drilling comprises the following steps:

[0023] 1) uniformly mixing a monofunctional monomer, an optional difunctional or higher monomer, an optional nonionic water-soluble polymer, an acidic resin, an optional nano powder and an auxiliary agent to obtain a first mixture;

[0024] 2) adding a photoinitiator to the first mixture and completely dissolving the photoinitiator to obtain a second mixture;

[0025] 3) filtering the second mixture and collecting the filtrate to obtain a third mixture;

[0026] 4) Degassing the third mixture to obtain the photocurable material.

[0027] In some specific embodiments, the second mixture is filtered using a microporous filter membrane, and the filtrate passing through the microporous filter membrane is collected; preferably, the pore size of the microporous filter membrane is ≤0.8 μm.

[0028] On the other hand, the aforementioned inkjet printing photocurable material for PCB drilling or the photocurable material prepared by the aforementioned preparation method is used in inkjet printing for PCB circuit board drilling.

[0029] On the other hand, an inkjet printing method of a photocurable material for PCB drilling includes selectively printing the aforementioned inkjet printing photocurable material for PCB drilling or the photocurable material prepared by the aforementioned preparation method on a PCB sheet that needs to be drilled, and after the printing is completed, drilling can be performed, and after the drilling is completed, the step of removing the film in water, aqueous liquid or alkaline film stripping liquid.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The inkjet printing photocurable material for PCB drilling of the present invention can utilize the characteristics of inkjet printing to selectively print at the position where the PCB needs to be drilled, thereby ensuring the drilling yield and quality. After the drilling is completed, it can be easily removed in water, aqueous liquid or alkaline film removal liquid without affecting the subsequent process of the target PCB board. The inkjet printing method for PCB drilling is simple to operate, energy-saving, greatly saves costs through selective printing, and is harmless to the human body. DETAILED DESCRIPTION

[0032] In order to make the technical problem, technical solution and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below. It should be understood that the specific implementation described herein is only used to explain the present invention and is not used to limit the present invention.

[0033] An inkjet printing photocurable material for PCB drilling comprises the following components in parts by weight:

[0034] 50-98 parts of monofunctional monomers, 0-15 parts of difunctional or higher monomers, 0-50 parts of nonionic water-soluble polymers, 1-50 parts of acidic resins, 0.1-10 parts of photoinitiators, 0.1-15 parts of nanopowders, and 0.1-10 parts of additives; wherein the acidic resin is selected from one or more polymer resins having acidic functional groups, and the acid value of the acidic resin ranges from 50-250 mgKOH / g.

[0035] The above-mentioned photocurable material provided by the present invention undergoes a polymerization reaction under the action of a photoinitiator, so that the photocurable material is cured to produce a temporary protective layer. And due to the control of the degree of crosslinking and the presence of an acidic resin, the protective film layer has good adhesion and film performance. The cured film layer is placed in water or an alkaline solution, and the swelling properties of the water molecules on the film layer or the destruction of the crosslinking degree and the acidic functional groups by the alkaline solution are utilized, resulting in the destruction of the curing system and the rapid fall-off of the cured film layer from the surface of the substrate. The above-mentioned photocurable material can be used for inkjet printing, and the coating of the drilling ink of the PCB is selectively printed on the surface of the substrate where the drilling position is required. After the printing is completed, the PCB is drilled. After the drilling is completed, the substrate with the holes drilled is placed in water, an aqueous liquid or an alkaline film-removing liquid, and the inkjet-printed PCB drilling ink coating is rapidly detached from the substrate, thereby obtaining a PCB substrate with the holes drilled, and does not affect the subsequent process of the PCB substrate.

[0036] In the present invention, the aqueous liquid includes a solution with water as a dispersion medium, such as a mixed solution of lower alcohols (methanol, ethanol, propanol, etc.) and water, a mixed solution of a water-soluble organic solvent and water that does not react with the molding material, an aqueous solution of a water-soluble inorganic salt (such as an aqueous sodium chloride solution), etc. The alkaline film stripping solution typically includes 3wt% ammonia water, 3wt% NaOH aqueous solution, etc., and can also be a commercially available common PCB-specific alkaline film stripping solution, including inorganic alkaline film stripping solution (for example: Ruishixing RS-1122B) and organic alkaline film stripping solution (Yanhua Chemical CL-6500, Aixier AXE-826), etc., but is not limited thereto.

[0037] In the present invention, the photocurable material is liquid at room temperature. In the inkjet printing process, the photocurable material does not need to be heated before entering the print head, or the heating temperature does not need to be too high (eg, ≤75° C.), thereby achieving the purpose of energy saving.

[0038] In the present invention, the monofunctional monomer is selected from one or more of a monofunctional acrylate monomer, a monofunctional acrylamide derivative monomer and a monofunctional vinyl monomer. The monofunctional acrylate monomer may be, for example, a monofunctional acrylate monomer commonly used in a photocuring reaction, specifically, β-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-octyl acrylate, isooctyl acrylate, lauryl acrylate, cyclohexyl acrylate, benzyl acrylate, phenoxyethyl acrylate, isobornyl acrylate, tetrahydrofuran acrylate, 2-methoxyethyl acrylate, triethylene glycol monomethyl ether ... acrylate, 3-ethyl-3-epoxypropyl methyl acrylate, 1-adamantyl methacrylate, γ-butyrolactone acrylate, ethoxyethoxyethyl acrylate, 3,3,5-trimethylcyclohexane acrylate, ethoxylated phenoxy acrylate, caprolactone acrylate (CA), methoxy polyethylene glycol monoacrylate, (2-ethyl-2-methyl-1,3-dioxolan-4-yl) acrylate, trimethylolpropane formal acrylate, alkoxy dodecyl acrylate, etc.

[0039] In the present invention, the monofunctional acrylamide derivative monomer may be a monofunctional acrylamide derivative monomer commonly used in photocuring reactions, such as acryloylmorpholine, N,N-dimethylacrylamide, N-hydroxyethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, N,N-dimethylaminopropylacrylamide, etc.

[0040] In the present invention, the monofunctional vinyl monomer may be a monofunctional vinyl monomer commonly used in photocuring reactions, such as N-vinyl pyrrolidone, N-vinyl caprolactam, N-vinylimidazole, vinyl ethyl ether, N-vinyl n-butyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, hydroxybutyl vinyl ether, 1,4-cyclohexanediol monovinyl ether, etc.

[0041] In the present invention, the amount of monofunctional monomer used is 50-98 parts by weight, for example, 51, 53, 55, 58, 60, 63, 65, 68, 70, 72, 75, 78, 80, 83, 85, 88, 90, 93, 95, 98 parts by weight, etc., preferably 55-95 parts by weight, and more preferably 60-90 parts by weight.

[0042] In the present invention, the monomer with a functionality of more than two is a difunctional monomer and a multifunctional monomer, which is selected from one or more photocurable acrylate monomers with a functionality of greater than or equal to 2, and can be a difunctional acrylate monomer commonly used in photocuring reactions, for example, 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropyl diacrylate, tricyclodecane dimethanol diacrylate, dioxane diol diacrylate, polypropylene glycol diacrylate, 1,6-hexanediol diacrylate, ethoxylated 1,6-hexanediol diacrylate, propoxylated 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, propoxylated 1,6-hexanediol diacrylate, Neopentyl glycol diacrylate, bisphenol A diacrylate, ethoxylated bisphenol A diacrylate, 2-methyl-1,3-propylene glycol diacrylate, etc.; trifunctional acrylate monomers, for example, tris(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, glycerol triacrylate, propoxylated glycerol triacrylate, etc.; multifunctional acrylate monomers, for example, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, etc.

[0043] In the present invention, the amount of the difunctional or higher monomer is 0-15 parts, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by weight, etc., preferably 1-13 parts by weight, and more preferably 3-10 parts by weight.

[0044] In the present invention, the nonionic water-soluble polymer is selected from one or more of polyvinyl alcohol, polyethylene glycol, polyacrylamide, polypyrrolidone, polyacryloylmorpholine and methylcellulose. The number average molecular weight of the polyvinyl alcohol can be in the range of 9000-25000, and commercially available polyvinyl alcohol products can be selected, such as 0488, 0499, 0588, 0599, 0899 and other polyvinyl alcohol products of Anhui Wanwei High-tech Materials Co., Ltd.

[0045] In the present invention, the number average molecular weight of the polyethylene glycol can be in the range of 1000-6000, and commercially available polyethylene glycol products can be selected, such as polyethylene glycol 1000, polyethylene glycol 1500, polyethylene glycol 2000, polyethylene glycol 3000, polyethylene glycol 3350, polyethylene glycol 4000, polyethylene glycol 6000 and other products produced by Tianjin Damao Chemical Reagent Factory.

[0046] In the present invention, the number average molecular weight of the polyacrylamide can be in the range of 1000-15000, and commercially available polyacrylamide products can be selected, such as polyacrylamide products with a number average molecular weight of 4000 produced by Sigma-Aldrich China Company.

[0047] In the present invention, the number average molecular weight of the polyacryloyl morpholine can be in the range of 1000 to 10000. The polyacryloyl morpholine can be purchased commercially, or can be prepared by entrusting or self-preparation. The preparation scheme can refer to patent CN107501477B.

[0048] In the present invention, the polyvinyl pyrrolidone can be selected from commercially available products, such as K30 (number average molecular weight of 40,000), K60 (number average molecular weight of 160,000), K90 (number average molecular weight of 360,000) and other polyvinyl pyrrolidone products produced by Tianjin Damao Chemical Reagent Factory.

[0049] In the present invention, the methyl cellulose can be selected from commercially available low-viscosity products, such as METHOCEL A15LV, METHOCEL A15C, METHOCEL E5 and other methyl cellulose products.

[0050] In the present invention, the amount of the nonionic water-soluble polymer is 0-50 parts by weight, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 20, 23, 25, 28, 30, 33, 35, 37, 40, 42, 45, 48, 50 parts by weight, etc., preferably 5-30 parts by weight, and more preferably 5-15 parts by weight.

[0051] In the present invention, the acidic resin refers to a polymer resin containing an acidic functional group, and the acidic functional group mainly refers to a carboxyl group, a phosphate group, and a sulfonic acid group. The acidic resin has an acid value ranging from 50 to 250 mgKOH / g, such as 50, 80, 100, 150, 200, 250 mgKOH / g, etc., and includes an acidic resin that can participate in a photocuring reaction and an acidic resin that does not participate in a photocuring reaction. The acidic resin that participates in a photocuring reaction includes Changxing Materials 648-1, 64801, 649, Hunan Dibang New Materials 6008W, Jiangmen Zicai Chemical ZC8629, etc., and the acidic resin that does not participate in a photocuring reaction includes a carboxyl-containing polyester resin, anhydride-modified epoxy resin, a carboxyl-modified acrylic resin, styrene maleic anhydride resin, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc.

[0052] In the present invention, the amount of the acidic resin is 1-50 parts by weight, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 20, 23, 25, 28, 30, 33, 35, 37, 40, 42, 45, 48, 50 parts by weight, etc., preferably 5-30 parts by weight, and more preferably 5-20 parts by weight.

[0053] In the present invention, the photoinitiator is a free radical photoinitiator, which can generate free radicals by appropriate light irradiation to induce the polymerization reaction of the monofunctional monomer. The free radical photoinitiator can be selected from benzophenone or its derivatives, benzil or its derivatives, anthraquinone or its derivatives, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzoin dimethyl ketal and other benzoin derivatives, diethoxyacetophenone, 4-tert-butyltrichloroacetophenone and other acetophenone derivatives, 2-dimethylaminoethyl benzoate, p-dimethylaminoethyl benzoate, diphenyl disulfide, thioxanthone or its derivatives, camphorquinone, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid, 7,7-dimethyl-2,3-dioxabicyclo[2.2.1]heptane-1-carboxy-2-bromoethyl ester, 7,7-dimethyl- Camphorquinone derivatives such as 2,3-dioxabicyclo[2.2.1]heptane-1-carboxy-2-methyl ester and 7,7-dimethyl-2,3-dioxabicyclo[2.2.1]heptane-1-carboxylic acid chloride, α-aminoalkylphenone derivatives such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, acylphosphine oxide derivatives such as benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoyldiethoxyphosphine oxide, 2,4,6-trimethylbenzoyldimethoxyphenylphosphine oxide and 2,4,6-trimethylbenzoyldiethoxyphenylphosphine oxide, etc.

[0054] In the present invention, the amount of the photoinitiator is 0.1-10 parts by weight, for example, 0.1, 0.3, 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight, etc.

[0055] In the present invention, the nano powder has a particle size range of 100-800 nm, such as 100, 200, 300, 400, 500, 600, 700, 800 nm, etc., and is selected from one or more of nano organic pigments, nano titanium dioxide, nano silicon dioxide, nano aluminum oxide, and nano barium sulfate. It mainly plays the role of color identification and improving hardness in ink. The nano powder can be ground by itself to prepare nano powder slurry, or it can be prepared by entrusting or purchased.

[0056] Exemplarily, the nano powder slurry can be prepared by conventional sand mill grinding, which is not limited in the present invention. For example, the nano powder slurry is prepared by the following method: dissolving the dispersant in the selected UV monomer or the mixture of the monomer and the resin, then adding the nano powder, stirring evenly; then grinding in a sand mill for 1-8 hours, the nano powder is completely dispersed in the slurry, and the particle size range of the dispersed particles is 100-800nm, preferably 100-500nm.

[0057] Specifically, the dispersant can be selected from commercially available dispersants, and only one type can be used, or two or more types can be used in combination, and the present invention does not limit this.Commercially available dispersants can include ANTI-TERRAU, ANTI-TERRA-U100, ANTI-TERRA-204, ANTI-TERRA-205, DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-108, DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-112, DISPERBYK-116, DISPERBYK-130, DISPERBYK-140, DISPERBYK-142, DISPERBYK-145, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-180, DISPERBYK-182, DISPERBYK-183, DISPERBYK-185, DISPERBYK-184, DISPERBYK-2000, DISPERBYK-2001, DISPERBYK-2009, DISPERBYK-2020, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2070, DISPERBYK-2096, DISPERBYK-2150, BYK-P104, BYK-P104S, BYK-P105, BYK-9076, BYK-9077, BYK-220S (manufactured by BYK-Chemie·JAPAN), DISPARLON2150, DISPARLON 1210, DISPARLON KS-860, DISPARLON KS-873N, DISPARLON 7004, DISPARLON 1830, DISPARLON 1860, DISPARLON1850, DISPARLON DA-400N, DISPARLON PW-36, DISPARLON DA-703-50 (manufactured by Kusumoto Chemicals), Flowlen G-450, Flowlen G-600, Flowlen G-820, Flowlen G-700, Flowlen DOPA-44, Flowlen DOPA-17 (manufactured by Kyoeisha Chemical Co., Ltd.), etc.

[0058] In the present invention, the amount of the nano powder is 0-15 parts by weight, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by weight, etc.

[0059] In the present invention, the auxiliary agent is selected from one or more of an inhibitor, a defoamer, and a leveling agent. Among them, the defoamer, the leveling agent, and the inhibitor used in the present invention are all auxiliary agents commonly used in existing photocuring reactions.

[0060] Specifically, the defoaming agent can be selected from at least one of the following products, such as: Deqian's products 2700, 3100, 5300, etc., Digao's products Foamex 810, Foamex N, Airex 920, Airex 986, etc., BYK's products BYK 055, BYK 088, BYK 020, BYK067A, etc., Efka's products EFKA 2720, EFKA 2721, etc.

[0061] The leveling agent can be selected from at least one of the following products, such as: products 431, 432, 488, 495, 810, etc. of Deqian Company, products Glide 100, Glide 432, Glide 435, Glide 440, Flow 300, Flow425, Flow ZFS 460, etc. of Digao Company, products BYK 333, BYK 371, BYK 373, BYK 361, TROY TroysolS366, etc. of BYK Company, products Perenol S71uv, Perenol S83uv, etc. of Corning Company, and products EFKA 3883, etc. of Efka Company.

[0062] The inhibitor can be selected from at least one of the following substances: methylhydroquinone, hydroquinone, 2,2-methylene-bis(4-methyl-6-tert-butylphenol), catechol, hydroquinone monomethyl ether, mono-tert-butylhydroquinone, p-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5-di-tert-butyl-p-benzoquinone, 2-butyl-4-hydroxyanisole, p-hydroxyanisole, hydroquinone, 2,6-di-tert-butyl-p-cresol, and commercial inhibitor products FIRSTCUREST-1, FIRSTCUREST-2, ZJ-701, etc.

[0063] In the present invention, the dosage of the auxiliary agent is 0.1-10 parts by weight, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight, etc.

[0064] The photocurable material of the present invention is a liquid at room temperature. Through the selection of ingredients and the adjustment of the proportion, the characteristic indicators can be achieved: the viscosity is 10-150cps and the surface tension is 20-40dyn at room temperature, the viscosity is 8-14cps and the surface tension is 20-38dyn at the injection temperature, wherein the injection temperature is not lower than room temperature. The preferred surface tension is 30-36dyn to avoid excessive diffusion of ink on the substrate, and it has good print head adaptability. The photocurable material of the present invention has a hardness of above H after curing, and can be quickly stripped in water, aqueous liquid or alkaline stripping liquid; preferably, when the thickness of the film layer coated with the photocurable material is 15μm, the time required for stripping by immersion in water, aqueous liquid or alkaline stripping liquid is less than or equal to 5min.

[0065] The present invention also provides a method for preparing the above-mentioned photocurable material, comprising the following steps:

[0066] According to the composition and proportion of the above-mentioned photocurable material, the monofunctional monomer, the difunctional monomer and the multifunctional monomer, the nonionic water-soluble polymer, the acidic resin, the slurry of the nano-powder grinding, and the additives are uniformly mixed to obtain a first mixture;

[0067] adding a photoinitiator to the first mixture and completely dissolving it to obtain a second mixture;

[0068] Filtering the second mixture, collecting the filtrate, and obtaining a third mixture;

[0069] The third mixture is subjected to a degassing treatment to obtain the photocurable material.

[0070] It is understandable that the above steps all need to be carried out in an environment outside the initiation wavelength range of the selected photoinitiator to avoid polymerization of the above monofunctional monomers under the action of the photoinitiator.

[0071] In a specific embodiment of the present invention, the second mixture is filtered by a microporous filter membrane, and the filtrate passing through the micropores is collected. Microporous filter membranes commonly used in the art can be used, such as glass fiber membranes, polypropylene membranes, etc. According to a specific embodiment of the present invention, the second mixture can be filtered more than twice by a step-by-step filtration method, wherein the pore size of the microporous filter membrane of the previous filtration is larger than the pore size of the microporous filter membrane of the next filtration, and the pore size of the microporous filter membrane used for the last filtration must be smaller than the pore size of the print head nozzle during inkjet printing. In a specific embodiment of the present invention, the second mixture is subjected to a secondary filtration, the first stage filtration uses a glass fiber membrane with a pore size of 0.80 μm, and the second stage filtration uses a glass fiber membrane or a nylon membrane with a pore size of 0.80 μm.

[0072] Furthermore, the degassing treatment is selected from at least one of reduced pressure degassing, normal pressure degassing and heating degassing, and the degassing time is not more than 5 hours.

[0073] In the present invention, the degassing treatment can ensure that the obtained photocurable material has excellent printing suitability, good fluidity during the printing process, and will not cause printing disconnection due to the interference of bubbles in the photocurable material. Therefore, the degassing conditions and degassing time can be adjusted according to actual conditions. For example, the degassing time can be 1-3 hours, and the degassing conditions can be selected from normal pressure, reduced pressure or heating, or a combination of multiple methods, for example, the third mixture is degassed at normal pressure for 1 hour, and then degassed at negative pressure for 1-3 hours.

[0074] The present invention also provides the above-mentioned photocurable material as a kind of ink for PCB drilling, which is mainly used for printing at the drilling position and assisting the drilling.

[0075] When printing with the photocurable material, it is directly and selectively printed on the surface of the substrate that needs to be drilled. The photocurable material undergoes a curing reaction to form a film layer that assists in PCB drilling. After the drilling is completed, the substrate printed with the photocurable material is placed in water or an aqueous liquid, or an alkaline film-removing liquid. Due to the swelling properties of the film layer by water molecules or the destruction of the cross-linking degree and acidic functional groups by the alkaline liquid, the curing system is destroyed and the cured film layer quickly falls off the surface of the substrate. Thus, the entire PCB drilling process is completed.

[0076] During the operation, the speed at which the cured film layer falls off and separates from the surface of the substrate can also be accelerated by spraying, accelerating stirring or heating, without damaging the PCB substrate.

[0077] As mentioned above, water, aqueous liquid or alkaline stripping liquid can be used to make the cured film layer fall off quickly from the PCB substrate. For example, the PCB substrate printed with the cured film layer of the photocurable material can be placed in water, hot water, ethanol aqueous solution, etc., or placed in an alkaline stripping liquid solution, so that the cured film layer can be quickly separated from the surface of the substrate to obtain a PCB substrate that has completed the drilling process.

[0078] The present invention is further explained below by more specific examples, but does not constitute any limitation.

[0079] The raw materials involved in the embodiments of the present invention are all conventional products purchased on the market, mainly as follows:

[0080] EOEOEA: Ethoxyethoxyethyl acrylate

[0081] HEA: Hydroxyethyl acrylate

[0082] ACMO: Acryloylmorpholine

[0083] THFA: Tetrahydrofurfuryl acrylate

[0084] CTFA: Cyclotrimethylolpropane formal acrylate

[0085] HEAA: Hydroxyethyl acrylamide

[0086] TPGDA: Tripropylene glycol diacrylate

[0087] HDDA: 1,6-Hexanediol diacrylate

[0088] DPGDA: Dipropylene glycol diacrylate

[0089] TMPTA: Trimethylolpropane triacrylate

[0090] PET4A: Pentaerythritol tetraacrylate

[0091] Changxing 648-1: Acrylate containing carboxylic acid group, acid value 210mgKOH / g

[0092] Dibang 6008W: Carboxyl-containing acrylic resin, acid value 200-225mgKOH / g

[0093] Zicai 8629: Acrylic resin containing carboxyl, acid value 170-210mg KOH / g

[0094] Photoinitiator 184: 1-Hydroxycyclohexylphenylketone

[0095] Photoinitiator TPO: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide

[0096] Photoinitiator ITX: 2-isopropylthioxanthone

[0097] Photoinitiator EDB: ethyl 4-(N,N-dimethylamino)benzoate

[0098] Photoinitiator 651: Benzoin diethyl ether

[0099] MEHQ: 4-Methoxyphenol

[0100] BHT: 2,6-di-tert-butylhydroxytoluene

[0101] IBOA: Isobornyl Acrylate

[0102] Changxing 6313-100: Fatty acid modified polyester acrylate, acid value 20mgKOH / g

[0103] Changxing DR-E618: polyester acrylate resin, acid value 15mgKOH / g.

[0104] Example

[0105] The composition and mass percentage of the photocurable material are shown in Table 1.

[0106] Table 1 Composition and formula of photocurable materials of Examples 1-7 and Comparative Examples 1-5

[0107]

[0108] The preparation methods of the photocurable materials of the above embodiments and comparative examples are as follows:

[0109] (1) First, grind the nano powder into a slurry with a solid content of 20%. The specific grinding method is to dissolve the dispersant in the UV monomer or the mixture of monomer and resin in the selected table, then add the nano powder and stir evenly; then place it in a sand mill and grind it for 1-8 hours until the nano powder is completely dispersed in the slurry and the particle size range is 100-800nm.

[0110] (2) mixing a monofunctional monomer, a difunctional monomer, a multifunctional monomer, a nonionic water-soluble polymer, an acidic resin, a nanopowder grinding slurry, and an additive to obtain a first mixture;

[0111] (3) adding a photoinitiator to the first mixture and mixing to obtain a second mixture;

[0112] (4) performing secondary filtration on the second mixture; wherein the first stage filtration uses a glass fiber membrane with a pore size of 0.80 μm produced by Shanghai Haoqing Environmental Protection Technology Co., Ltd., and the second stage filtration uses a glass fiber membrane or nylon membrane with a pore size of 0.80 μm produced by Shanghai Yiling Filtration Equipment Co., Ltd., and collects the filtrate to obtain a third mixture;

[0113] (5) The third mixture is first degassed at normal pressure for about 1 hour, and then degassed at reduced pressure at -0.05 to -0.1 atmospheres for about 1 hour to obtain the photocurable material.

[0114] The performance test of the photocurable material is as follows, and the test results are shown in Table 2.

[0115] (1) Viscosity and surface tension measurement: The viscosity and surface tension of the photocurable material at room temperature (25°C) and the viscosity at the injection temperature were tested using a DV2T digital viscometer and a BZY-1 fully automatic surface tension meter.

[0116] (2) Determination of film fading time: Use a photocurable material to print a color block of 10×10 cm on the surface of the copper clad laminate. The thickness of the color block is about 15 μm. After printing and curing, immerse the sample in the selected film fading solution and perform magnetic stirring at the test temperature to observe the time for complete film fading. The H2O indicates a pure aqueous solution and the NaOH indicates a 3wt% NaOH aqueous solution.

[0117] (3) Adhesion: Use photocurable material to print a 10×10 cm color block on the surface of the copper clad laminate. The thickness of the color block is about 15 μm. After printing and curing, use a grid marker to draw 10×10 1 mm squares on the cured film. Use 3M special transparent tape to stick to the grid area, pull it 180° quickly, and observe whether the cured film on the copper clad laminate falls off. It is divided into 0 to 5 levels according to the shedding situation. No shedding is the best level 0, shedding exists and the shedding area accounts for less than 10% is level 1, shedding is not less than 10% and less than 30% is level 2, shedding area is not less than 30% and less than 50% is level 3, shedding area is not less than 50% and less than 70% is level 4, and shedding area is not less than 70% is level 5. Test three times, and the worst result is recorded.

[0118] (4) Pencil hardness: Use photocurable material to print a 10×10cm color block on the surface of the copper clad laminate. The color block thickness is about 15μm. After printing and curing, the test piece is prepared. Use a pencil to make a 45° angle with the test piece and scratch it hard. Do not break the lead. Scratch about 1cm in front of the tester at a constant speed. The scratching speed is 1cm / s. After scratching once, the tip of the lead should be re-grinded. Repeat the test 5 times with a pencil with the same hardness mark. When observing the damage of the coating for evaluation, if only 2 or less of the 5 tests show the base material or primer coating, the same test should be performed with a pencil with a larger hardness mark. When the coating is damaged more than 2 times (every 5 tests), the hardness mark of the last pencil can be read as the pencil hardness.

[0119] The measurement results of various indicators are recorded in Table 2 below.

[0120] Table 2 Performance test results of photocurable materials in Examples 1-8

[0121]

[0122]

[0123] By comparing the embodiments and the comparative examples, it can be seen that when the formula is different, especially when no acidic resin is used or a low acid value resin is used, the swelling performance of the film layer decreases. At the same time, as the acid value decreases, the ability of the alkali solution to the crosslinking degree and acidic functional groups of the film layer will also decrease, resulting in difficulty in film removal, or even complete inability to remove the film.

[0124] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An inkjet printing photocurable material for PCB drilling, characterized in that: The composition comprises the following components in parts by weight: 50-98 parts of monofunctional monomer, 0-15 parts of difunctional or higher monomer, 0-50 parts of nonionic water-soluble polymer, 1-50 parts of acidic resin, 0.1-10 parts of photoinitiator, 0-15 parts of nano powder, 0.1-10 parts of auxiliary agent; Wherein, the acidic resin is selected from one or more polymer resins having acidic functional groups, and the acid value of the acidic resin is in the range of 50-250 mgKOH / g.

2. The inkjet printing photocurable material for PCB drilling according to claim 1, characterized in that: The monofunctional monomer is selected from one or more of a monofunctional acrylate monomer, a monofunctional acrylamide derivative monomer or a monofunctional vinyl monomer; and / or The monomer having bifunctionality or higher is selected from one or more of bifunctional acrylate monomers and multifunctional acrylate monomers; and / or The photoinitiator is selected from free radical photoinitiators.

3. The inkjet printing photocurable material for PCB drilling according to claim 1, characterized in that: The nonionic water-soluble polymer is selected from one or more of polyvinyl alcohol, polyethylene glycol, polyacrylamide, polypyrrolidone, polyacryloylmorpholine or methylcellulose.

4. The inkjet printing photocurable material for PCB drilling according to claim 1, characterized in that: The nano powder is selected from one or more of nano organic pigments, nano titanium dioxide, nano silicon dioxide, and nano aluminum oxide; preferably, the particle size range is 100-800 nm.

5. The inkjet printing photocurable material for PCB drilling according to claim 1, characterized in that: The auxiliary agent is selected from one or more of an inhibitor, a defoamer or a leveling agent.

6. The inkjet printing photocurable material for PCB drilling according to any one of claims 1 to 5, characterized in that: The photocurable material is liquid at room temperature; Preferably, the photocurable material has a viscosity of 10-150 cps and a surface tension of 20-40 dyn at room temperature, and a viscosity of 8-14 cps and a surface tension of 20-38 dyn at the injection temperature, wherein the injection temperature is not lower than room temperature; More preferably, the hardness of the photocurable material after curing is above H, and the photocurable material can be rapidly delaminated in water, aqueous liquid or alkaline delamping liquid; Further preferably, when the photocurable material is used to coat a film layer with a thickness of 15 μm, the time required for film stripping by immersion in water, aqueous liquid or alkaline film stripping liquid is less than or equal to 5 minutes.

7. The method for preparing the inkjet printing photocurable material for PCB drilling according to any one of claims 1 to 6, characterized in that: The steps include: 1) uniformly mixing a monofunctional monomer, an optional difunctional or higher monomer, an optional nonionic water-soluble polymer, an acidic resin, an optional nano powder and an auxiliary agent to obtain a first mixture; 2) adding a photoinitiator to the first mixture and completely dissolving the photoinitiator to obtain a second mixture; 3) filtering the second mixture and collecting the filtrate to obtain a third mixture; 4) Degassing the third mixture to obtain the photocurable material.

8. The preparation method according to claim 7, characterized in that: The second mixture is filtered through a microporous filter membrane, and the filtrate passing through the microporous filter membrane is collected; preferably, the pore size of the microporous filter membrane is ≤0.8 μm.

9. Use of the inkjet printing photocurable material for PCB drilling according to any one of claims 1 to 6 or the photocurable material prepared by the preparation method according to any one of claims 7 to 8 in inkjet printing for PCB circuit board drilling.

10. An inkjet printing method for a photocurable material for PCB drilling, characterized in that: The method comprises the steps of selectively printing on a PCB sheet material to be drilled using the inkjet printing photocurable material for PCB drilling as described in any one of claims 1 to 6 or the photocurable material prepared by the preparation method as described in any one of claims 7 to 8, drilling can be performed after printing is completed, and removing the film in water, aqueous liquid or alkaline film stripping liquid after drilling is completed.

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