Radiation-curable compositions for plating applications

Abstract

To provide a radiation curable composition that may be used as a plating resist in the manufacture of PCBs, more specifically a plating resist that performs well in the ENIG process, and a method of manufacturing a plated article.SOLUTION: A radiation curable composition comprises: a) at least one monofunctional (meth)acrylate containing a carboxylic acid group, a phosphoric acid group or a phosphonic acid group; b) an acrylamide; and c) at least one polyfunctional (meth)acrylate, and further comprises at least 0.1 wt.% of a liquid penetration controlling monomer selected from the group consisting of a C6-C20 alkyl (meth)acrylate, a fluorinated (meth)acrylate and a silicone (meth)acrylate.SELECTED DRAWING: None

Description

Technical Field

[0001] Technical field of invention The present invention relates to radiation-curable compositions for use in various plating applications, such as those used in PCB manufacturing, preferably UV-curable inkjet inks.

Background Art

[0002] Background Art for the Invention The manufacturing workflow of printed circuit boards (PCBs) is gradually shifting from the standard workflow to the digital workflow in order to reduce the amount of process steps and to reduce the cost and environmental impact of PCB manufacturing. The digital workflow further allows for the possibility of short-run manufacturing or even the manufacturing of individual parts without significantly increasing costs. Moving from an analog workflow to a digital workflow thus has clear economic and environmental benefits.

[0003] Inkjet printing has been proposed as one of the preferred digital manufacturing methods for various stages of the PCB manufacturing process, which proceeds from the etch resist through the solder mask to the legend printing. The preferred inkjet ink is a UV-curable inkjet ink.

[0004] In PCB manufacturing, several plating methods are also used, such as copper plating, nickel plating, gold plating, etc.

[0005] The ENIG (electroless nickel immersion gold) plating method is a surface finishing method commonly used in PCB manufacturing.

[0006] The ENIG method consists of depositing thin layers of nickel and gold on the exposed copper areas within the PCB in order to provide excellent solderability and excellent protection against oxidation.

[0007] One of the problems associated with the ENIG method is its cost due to the use of expensive metals like gold. Since it's not necessary to protect all exposed copper areas, a digital workflow would be more cost-effective. Such a digital workflow would also enable the manufacture of PCBs with various surface finishes, such as ENIG and tin-dipped PCBs.

[0008] To implement such a digital workflow, a protective layer must be applied to the copper areas that do not need to be plated. Nickel and gold are then applied only to the exposed copper areas, and finally, the protective layer must be removed (stripped) to obtain the final substrate.

[0009] When inkjet inks are used as etching resists, solder masks, legend inks, or plating resists, adhesion of the sprayed and cured inkjet ink to various substrates is extremely important. Furthermore, when used as an etching resist or plating resist, the ink layer (protective layer) must be completely removed after etching or plating.

[0010] When used as a plating resist in the ENIG process, the challenge for the protective layer is that it must withstand the strong and varied conditions (pH, temperature) used during the ENIG process while being completely removed during the stripping stage.

[0011] Patent Document 1 (Agfa Gevaert NV) discloses an etching-resistant UV-curable inkjet ink for the production of conductive patterns. The polymerizable composition of the ink consists of 15 to 70 wt% acrylamide; 20 to 75 wt% polyfunctional acrylate; and 1 to 15 wt% monofunctional (meth)acrylate containing a carboxylic acid group, a phosphoric acid group, or a phosphonic acid group. Similar UV-curable inkjet inks are disclosed in Patent Document 2 (Agfa NV and Agfa Gevaert NV) for the production of embossed portions for decorative purposes, and in Patent Document 3 (Agfa Gevaert NV) for digital secondary processing of metal products. In the latter application, digital secondary processing may include etching or plating steps. However, examples using plating for the production of metal products are not disclosed, and no information regarding the specific composition of the plating bath, particularly regarding pH values, is disclosed. All disclosed etching-resistant inkjet inks are compatible with an acidic etching step (pH less than 3) followed by a medium to strong alkaline stripping step.

[0012] To expand the range of applications of inkjet methods in PCB manufacturing, there is a need for inkjet inks that function well as plating resists, particularly in ENIG plating processes.

[0013] This time, it was found that a radiation-curable composition according to the present invention can achieve the objectives of the present invention. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] International Publication No. 2016 / 050504 Brochure [Patent Document 2] International Publication No. 2016 / 050372 Brochure [Patent Document 3] International Publication No. 2016 / 050371 Pamphlet [Overview of the Initiative] [Problems that the invention aims to solve]

[0015] Outline of the invention The object of the present invention is to provide a radiation-curable composition that can be used as a plating resist in the manufacture of PCBs, and more specifically, as a plating resist that works well in the ENIG process. [Means for solving the problem]

[0016] The object of the present invention is achieved by a radiation-curable composition according to claim 1.

[0017] Another object of the present invention is to provide a method for producing PCBs.

[0018] The object of the present invention is achieved by the method according to claim 9.

[0019] Further objectives of the present invention will become apparent from the following description.

[0020] Detailed description of the invention definition For example, the term "monofunctional" in monofunctional polymerizable compounds means that the polymerizable compound contains one polymerizable group.

[0021] For example, the term "bifunctional group" in "bifunctional polymerizable compound" refers to a polymerizable compound. This means that it contains two polymerizable groups.

[0022] For example, the term "polyfunctional" in polyfunctional polymerizable compounds means that the polymerizable compound contains more than two polymerizable groups.

[0023] The term "alkyl" refers to all possible variations with respect to the number of carbon atoms in an alkyl group, namely methyl, ethyl, n-propyl and isopropyl in the case of three carbon atoms; n-butyl, isobutyl and tertiary butyl in the case of four carbon atoms; and n-pentyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl and 2-methylbutyl in the case of five carbon atoms.

[0024] Unless otherwise specified, the substituted or unsubstituted alkyl group is preferably a C1 to C6 alkyl group.

[0025] Unless otherwise specified, the substituted or unsubstituted alkenyl group is preferably a C2 to C6 alkenyl group.

[0026] Unless otherwise specified, the substituted or unsubstituted alkynyl group is preferably a C2 to C6 alkynyl group.

[0027] Unless otherwise specified, the substituted or unsubstituted alkaryl group is preferably a phenyl or naphthyl group containing 1, 2, 3 or more C1 to C6 alkyl groups.

[0028] Unless otherwise specified, the substituted or unsubstituted aralkyl group is preferably a C7 to C7 group containing a phenyl group or a naphthyl group. 20 -It is an alkyl group.

[0029] Unless otherwise specified, the substituted or unsubstituted aryl group is preferably a phenyl group or a naphthyl group.

[0030] Unless otherwise specified, the substituted or unsubstituted heteroaryl group is preferably a 5- or 6-membered ring substituted with 1, 2, or 3 oxygen atoms, nitrogen atoms, sulfur atoms, selenium atoms, or a combination thereof.

[0031] For example, the term "substituted" in substituted alkyl groups means that the alkyl group may be substituted with atoms other than those normally present in such groups, namely carbon and hydrogen. For example, substituted alkyl groups may contain halogen atoms or thiol groups. Unsubstituted alkyl groups contain only carbon and hydrogen atoms.

[0032] Unless otherwise specified, substituted alkyl groups, substituted alkenyl groups, substituted alkynyl groups, substituted aralkyl groups, substituted alkaryl groups, substituted aryl and substituted heteroaryl groups are preferably substituted with one or more substituents selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tertiary butyl, esters, amides, ethers, thioethers, ketones, aldehydes, sulfoxides, sulfones, sulfonate esters, sulfonamides, -Cl, -Br, -I, -OH, -SH, -CN and -NO2. ru.

[0033] Radiation curable composition Radiation-curable composition according to the present invention: a) Acrylamide; b) At least one monofunctional group comprising a carboxylic acid group, a phosphate group, or a phosphonic acid group (meta ) Acrylate; c) At least one polyfunctional (meth)acrylate The radiation-curable composition further comprises d) at least 0.1% by weight of a liquid penetrating controlling monomer selected from the group consisting of long-chain alkyl (meth)acrylates, fluorinated (meth)acrylates, and silicone (meth)acrylates.

[0034] The radiation-curable composition may further contain other components such as photoinitiators, colorants, polymer dispersants, polymerization inhibitors, flame retardants, or surfactants.

[0035] Radiation-curable compositions can be cured by any type of radiation, for example, by an electron beam, but are preferably cured by UV rays, and more preferably by UV rays from UV LEDs. Thus, radiation-curable compositions are preferably UV-curable compositions.

[0036] The material is a radiation-curable composition, preferably a radiation-curable inkjet ink, and more preferably a UV-curable inkjet ink.

[0037] For reliable industrial inkjet printing, the viscosity of the inkjet ink is preferably all 1000s. -1 The shear rate is 20 mPa.s or less at 45°C, more preferably between 1 mPa.s and 18 mPa.s at 45°C, and most preferably between 4 mPa.s and 14 mPa.s at 45°C.

[0038] The preferred injection temperature is between 10°C and 70°C, more preferably between 20°C and 55°C, and most preferably between 25°C and 50°C.

[0039] For excellent image quality and adhesion, the surface tension of the inkjet ink is preferably in the range of 18 to 70 mN / m at 25°C, and more preferably in the range of 20 to 40 mN / m at 25°C.

[0040] Acrylamide The radiation-curable composition according to the present invention contains acrylamide.

[0041] The amount of acrylamide is preferably at least 7.5 to 60% by weight, more preferably at least 15 to 50% by weight, and most preferably at least 20 to 40% by weight, with all weight percentages (wt%) based on the total weight of the radiation-curable composition. The acrylamides referred to herein have a chemical structure according to formula I, [ka] During the ceremony, R1 represents a hydrogen or methyl group. R2 and R3 are hydrogen, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted aralkyl groups, substituted or unsubstituted alkaryl groups, substituted or unsubstituted non- This indicates a substituted aryl group or a substituted or unsubstituted heteroaryl group. R2 and R3 can represent atoms necessary for the formation of a 5- to 8-membered ring.

[0042] Preferably, R1 represents hydrogen, and R2 and R3 have atoms necessary for the formation of a 5- to 8-membered ring. do.

[0043] One type of acrylamide or a mixture of acrylamides can be used.

[0044] Preferred acrylamides are disclosed in Table 1. [Table 1]

[0045] A very preferred acrylamide according to formula I is acryloylmorpholine (ACMO). ru.

[0046] Acid group-containing (meth)acrylate The radiation-curable composition according to the present invention comprises a (meth)acrylate containing a carboxylic acid group, a phosphate group, or a phosphonic acid group; or a mixture thereof.

[0047] The amount of (meth)acrylate containing a carboxylic acid group, a phosphoric acid group, or a phosphonic acid group is preferably between 1% and 25% by weight, more preferably between 3% and 20% by weight, and most preferably between 5% and 15% by weight, with all weight percentages (weight%) based on the total weight of the radiation-curable composition.

[0048] (Meth)acrylates containing such carboxylic acid groups, phosphate groups, or phosphonic acid groups have been observed to improve the adhesion of sprayed and cured radiation-curable compositions on various substrates. Therefore, these compounds are also called adhesion promoters.

[0049] Suitable examples of carboxylic acid group-containing (meth)acrylates include the compound shown by formula (II): [ka] During the ceremony, n is either 0 or 1. R4 consists of a hydrogen atom, a substituted or unsubstituted alkyl group, and a substituted or unsubstituted aryl group. Selected from the group, L1 represents a divalent linking group containing 20 or fewer carbon atoms, where L1 is linked to the carboxylic acid via an aliphatic carbon atom. X indicates O or NR7. R7 is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, Selected from the group consisting of substituted or unsubstituted alkynyl groups, substituted or unsubstituted alkaryl groups, substituted or unsubstituted aralkyl groups, and substituted or unsubstituted (hetero)aryl groups, R7 and L1 can represent atoms necessary for the formation of a 5- to 8-membered ring. R5 and R6 are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups.

[0050] R4 is preferably a hydrogen atom or a substituted or unsubstituted C1 to C4 alkyl group, more preferably The atom is either a hydrogen atom or a methyl group, with a hydrogen atom being particularly preferred.

[0051] X is preferably an oxygen atom or NH, with an oxygen atom being particularly preferred.

[0052] L1 preferably represents a substituted or unsubstituted alkylene group, and the unsubstituted alkylene group is particularly preferable.

[0053] Adhesion promoters according to Formula II or salts thereof can be copolymerized with other polymerizable compounds of radiation-curable inkjet inks.

[0054] Table 2 shows examples of adhesion promoters that conform to formula II. [Table 2-1]

[0055] [Table 2-2]

[0056] Preferred examples of (meth)acrylates containing a phosphate group or a phosphonic acid group include 2-(methac It contains liloyloxyethyl phosphate, hydroxyethyl methacrylate phosphate, and bis-(2-methacryloyloxyethyl) phosphate.

[0057] Preferred examples of (meth)acrylates containing a phosphate group are compounds according to formula P-1 or P-2: [ka] In the formula, R is C n H 2n+1 This shows that n is an integer between 6 and 18.

[0058] Table 3 discloses preferred examples of (meth)acrylates containing a phosphate group. [Table 3]

[0059] In a particularly preferred embodiment of the UV-curable inkjet ink, the (meth)acrylate containing a carboxylic acid group, a phosphoric acid group, or a phosphonic acid group is selected from the group consisting of acrylic acid, 2-carboxyethyl acrylate, 2-acryloylethyl succinate, and 2-hydroxyethyl methacrylate phosphate or mixtures thereof.

[0060] Polyfunctional acrylates The radiation-curable composition according to the present invention comprises a polyfunctional acrylate.

[0061] The amount of polyfunctional acrylate is preferably between 15% and 65% by weight, preferably 2% by weight. The polyfunctional acrylate is between 0% and 55% by weight, and most preferably between 30% and 50% by weight, with all weight percentages (wt%) based on the total weight of the radiation-curable composition.

[0062] One type of polyfunctional acrylate or a mixture of polyfunctional acrylates can be used.

[0063] In a preferred embodiment, the polyfunctional acrylate is selected from the group consisting of dipropylene glycol diacrylate, neopentyl glycol diacrylate, neopentyl glycol (2x propoxylated) diacrylate, pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, tripropylene glycol diacrylate, ditrimethyloylpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, and polyethylene glycol diacrylate.

[0064] In the most preferred embodiment of the UV-curable inkjet ink, the polyfunctional acrylate includes neopentyl glycol hydroxypivalate diacrylate.

[0065] Liquid permeability controlled monomer The radiation-curable composition contains at least 0.1% by weight of a liquid penetration control monomer selected from the group consisting of long-chain alkyl (meth)acrylates, fluorinated (meth)acrylates, and silicone (meth)acrylates or mixtures thereof, where the weight percentage is relative to the total weight of the radiation-curable composition.

[0066] The amount of liquid penetration control monomer is preferably at least 0.1% by weight, more preferably at least 0.5% by weight, most preferably at least 1% by weight, and at least 1.5% by weight is particularly preferred, with all weight percentages (wt%) based on the total weight of the radiation-curable composition.

[0067] The amount of liquid penetration control monomer is preferably between 0.1% and 10% by weight, more preferably between 0.5% and 7.5% by weight, and most preferably between 1.5% and 5% by weight, with all weight percentages (weight%) based on the total weight of the radiation-curable composition.

[0068] Long-chain alkyl (meth)acrylates The long-chain alkyl (meth)acrylate is C6-C22 alkyl (meth)acrylate, more preferably C8-C20 alkyl (meth)acrylate, and most preferably C12-C18 alkyl (meth)acrylate.

[0069] As used herein, C6-C22, C8-C20, and C12-C18 alkyl (meth)acrylates mean alkyl esters of (meth)acrylic esters having alkyl groups of 6 to 22, 8 to 20, and 12 to 18 carbon atoms, respectively.

[0070] The alkyl chains referred to herein may include linear, branched, or cyclic alkyl groups.

[0071] Examples of such alkyl (meth)acrylates include lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, docosyl (meth)acrylate, or icosyl (meth)acrylate. It can be done.

[0072] A particularly preferred long-chain acrylate is lauryl acrylate.

[0073] A mixture of various long-chain alkyl (meth)acrylates can be used.

[0074] Fluorinated (meth)acrylate As used herein, fluorinated (meth)acrylate means a (meth)acrylate comprising an alkyl chain functionalized with fluorine atoms, preferably with at least two fluorine atoms, and more preferably with at least three fluorine atoms.

[0075] Alkyl chains referred to herein may include linear, branched, or cyclic alkyl groups.

[0076] Examples of fluoropolymerizable compounds include 2,2,2-trifluoroethyl-α-fluoroacrylate (TFEFA), 2,2,2-trifluoroethyl-methacrylate (TFEMA), 2,2,3,3-tetrafluoropropyl-α-fluoroacrylate (TFPFA), 2,2,3,3-tetrafluoropropyl-methacrylate (TFPMA), 2,2,3,3,3-pentafluoropropyl-α-fluoroacrylate (PFPFA), 2,2,3,3,3-pentafluoropropyl-methacrylate (PFPMA), 1H,1H-perfluoro-n-octyl acrylate, 1H,1H-perfluoro-n-decyl acrylate, 1H,1H-perfluoro-n-octyl methacrylate, 1H,1H-perfluoro-n-decyl methacrylate, 1H,1H,6H,6H-perfluoro-1,6-hexanediol diacrylate, 1H,1H,6H,6H-perfluoro-1,6-hexanediol dimethacrylate, 2-(N-butylperfluorooctanesulfonamide)ethyl acrylate, 2(N-ethylperfluorooctanesulfonamide)ethyl acrylate, 2(N-ethylperfluorooctanesulfonamide)ethyl methacrylate, C8F 17 CH2CH2OCH2CH2-OOC-CH=CH2 and C8F 17 CH2CH2O CH2CH2-OOC-C(CH3)=CH2 are included.

[0077] Preferred fluorinated (meth)acrylates are MEGAFACE TM RS-75, MEGAFACE TM RS-72-K, MEGAFACE TM RS-76-E, MEFAFACE TM 76-NS, MEGAFACE TM 78, MEGAFACE TM RS-90, MEFAFACE TM RS-55, MEFAFACE TM MEGAFACE available from DIC Corporation such as RS-56 TM is the RS series.

[0078] A particularly preferred fluorinated (meth)acrylate is 2,2,2-trifluoroethyl methacrylate.

[0079] A mixture of various fluorinated (meth)acrylates can be used.

[0080] Silicone (meth)acrylate As used herein, silicone (meth)acrylate means a (meth)acrylate containing at least one group containing a Si atom.

[0081] Preferred silicone (meth)acrylates have a chemical structure according to formula S-1, [ka] During the ceremony, R8 and R9 represent alkyl groups or aryl groups that can be optionally substituted independently of each other; n represents an integer between 1 and 50.

[0082] Preferably, R8 and R9 represent alkyl groups, more preferably methyl groups.

[0083] Preferably, n is an integer between 1 and 25, more preferably between 2 and 15.

[0084] Preferred silicone acrylates are polyether-modified (meth)acrylated polydimethylsiloxane or polyester-modified (meth)acrylated polydimethylsiloxane.

[0085] A preferred commercially available silicone (meth)acrylate is Ebecryl, a silicone diacrylate from Cytec. TM 350; All polyether-modified acrylated polydimethylsiloxanes manufactured by BYK Chemie TM UV3500 and BYK TMUV3530, polyester-modified acrylated polydimethylsiloxane BYK TM UV3570; Tego from EVONIK TM Rad 2100, Tego TM Rad 2200N, Tego TM Rad 2250N, Tego TM Rad 2300, Tego TM Rad 2500, Tego TM Rad 2600 and Tego TM Rad 2700, Tego TM RC711; Silaplane, all manufactured by Chisso Corporation. TM FM7711, Silaplane TM FM7721, Silaplane TM FM7731, Silaplane TM FM0711, Silaplane TM FM0721, Silaplane TM FM0725, Silaplane TM TM0701, Silaplane TM TM0701T; All DMS-R05, DMS-R11, DMS-R18, DMS-R22, DMS-R31, DMS-U21, DBE-U22, SIB1400, RMS-044, RMS-033, RMS-083, UMS-182, UMS-992, UCS-052, RTT-1011 and UTT-1012 manufactured by Gelest, Inc., and all SILMER manufactured by Siltech. TM ACR D208, SILMER TM Di-50, SILMER TM Di1508, SILMER TM Di-2510, SILMER TM Di-4515-O, SILMER TM ACR Di-10 is included.

[0086] A mixture of various silicone (meth)acrylates can be used.

[0087] Other monomers The radiation-curable composition may contain other monomers, oligomers, and / or prepolymers in addition to the above monomers.

[0088] In a preferred embodiment, such monomers, oligomers, or prepolymers contain an acrylate group as a polymerizable group.

[0089] Preferred monomers and oligomers are listed in sections

[0106] to

[0115] of European Patent No. A 1911814.

[0090] Other monomers are preferably monofunctional monomers, more preferably monofunctional acrylates or methacrylates.

[0091] Photoinitiator The radiation-curable composition preferably contains a photoinitiator.

[0092] Free radical photoinitiators are chemical compounds that, upon exposure to chemical rays, initiate polymerization of monomers and oligomers by forming free radicals. Nourish type I initiators are initiators that cleave after excitation, immediately yielding an initiating free radical. Nourish type II initiators are photoinitiators that are activated by chemical rays and form free radicals by hydrogen abstraction from a second compound that becomes the actual initiating free radical. This second compound is called a polymerization synergist or co-initiator. Both type I and type II photoinitiators can be used individually or in combination in this invention.

[0093] Suitable photoinitiators are disclosed in CRIVELLO, JV, et al. Photoinitiators for Free Radical, Cationic and Anionic Photopolymerization. 2nd edition, BRADLEY, G. (ed.), London, UK: John Wiley and Sons Ltd, 1998. pp. 276-293.

[0094] Specific examples of free radical photoinitiators may include, but are not limited to, the following compounds or combinations thereof: benzophenones and substituted benzophenones; 1-hydroxycyclohexylphenyl ketones; thioxanthones such as isopropylthioxanthones; 2-hydroxy-2-methyl-1-phenylpropan-1-one; 2-benzyl-2-dimethylamino-(4-morpholinophenyl)butan-1-one; benzyldimethyl ketals; bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; 2,4,6-trimethoxybenzoyl-diphenylphosphine oxide; and 2,4,6-trimethylbenzoyl-diphenylphosphine.

[0095] 2-Methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one; 2,2-dimethoxy-1,2-diphenylethane-1-one or 5,7-diiodo-3-butoxy-6-fluorene.

[0096] Suitable commercially available free radical photoinitiators include, for example, Omnirad from IGM. TM Omnipol TM and Esacure TM This includes type photoinitiators. Examples of such photoinitiators include Omnirad 379, Omnirad 369, Omnirad 819, Omnirad 184, Omnirad 2959, Omnipol ASA, and Esacure KIP 150.

[0097] A preferred amount of photoinitiator is 0.1–20% by weight, more preferably 2–15% by weight, and most preferably 3–10% by weight, of the total weight of the radiation-curable inkjet ink.

[0098] To further improve photosensitivity, radiation-curable inkjet may contain co-initiators. Suitable examples of co-initiators can be classified into three groups: 1) methyldiethanolamine, dimethylethanolamine, triethanolamine, triethylamine (1) Tertiary aliphatic amines such as n and N-methylmorpholine; (2) Aromatic amines such as amyl-p-dimethylaminobenzoate, 2-n-butoxyethyl-4-(dimethylamino)benzoate, 2-(dimethylamino)-ethylbenzoate, ethyl-4-(dimethylamino)benzoate and 2-ethylhexyl-4-(dimethylamino)benzoate; and (3) (meth)acrylated amines such as dialkylaminoalkyl (meth)acrylate (e.g., diethylaminoethyl acrylate) or N-morpholinoalkyl-(meth)acrylate (e.g., N-morpholinoethyl acrylate). Preferred co-initiators are aminobenzoates.

[0099] Coloring agents The radiation-curable composition may be substantially colorless, but preferably it contains at least one colorant. The colorant makes the temporary mask clearly visible to the conductive pattern maker, allowing for visual inspection of the quality.

[0100] The colorant may be a pigment or a dye, but preferably a dye that is not bleached by the UV curing step during the inkjet printing process of UV-curable inkjet ink.

[0101] The pigments can be black, white, cyan, magenta, yellow, red, orange, violet, blue, green, brown, or mixtures thereof. Coloring pigments can be selected from those disclosed in HERBST, Willy, et al. Industrial Organic Pigments, Production, Properties, Applications, 3rd edition. Wiley-VCH, 2004, ISBN 3527305769.

[0102] Suitable pigments are disclosed in sections

[0128] through

[0138] of International Publication No. 2008 / 074548.

[0103] The pigment particles in inkjet ink must be small enough to allow free flow of ink through the inkjet printing apparatus, particularly at the ejection nozzle. Smaller particles are desirable for maximum color density and to slow down sedimentation. Most preferably, the average pigment particle size is 150 nm or less. The average pigment particle size is preferably determined using a Brookhaven Instruments Particle Sizer BI90plus based on the principle of dynamic light scattering.

[0104] Generally, dyes exhibit higher photofading than pigments, but do not cause problems with ink jetting. Anthraquinone dyes have been found to exhibit only slight photofading under normal UV curing conditions used in UV-curable inkjet printing.

[0105] In a preferred embodiment, the colorant in the radiation-curable composition is an anthraquinone dye such as Macrolex™ Blue 3R (CASRN 325781-98-4) from LANXESS.

[0106] Other preferred dyes include crystal violet and copper phthalocyanine dyes.

[0107] In a preferred embodiment, the colorant is present in an amount of 0.5 to 6.0% by weight, more preferably 1.0 to 2.5% by weight, based on the total weight of the radiation-curable composition.

[0108] Polymer dispersant When the colorant in the radiation-curable composition is a pigment, the radiation-curable composition preferably contains a dispersant, more preferably a polymer dispersant, for the dispersion of the pigment.

[0109] Suitable polymeric dispersants are copolymers of two monomers, but they can also contain three, four, five, or even more monomers. The properties of the polymeric dispersant depend on both the properties of the monomers and their distribution in the polymer. Copolymer dispersants preferably have the following polymer composition: Randomly polymerized monomers (for example, monomers A and B polymerized in the order ABBAABAB); alternatingly polymerized monomers (for example, monomers A and B polymerized in the order ABABABAB); Gradient-polymerized (tapered) monomers (for example, monomers A and B polymerized into AAABAABBABBB); The block length of each block (2, 3, 4, 5 or even more) is important to the dispersive ability of the polymeric dispersant (e.g., monomers A and B polymerized to AAAAABBBBBB); Graft copolymers (graft copolymers consist of a polymer main chain having polymer side chains bonded to the main chain); and These polymers are mixed in various forms, such as block-like gradient copolymers.

[0110] Suitable polymeric dispersants are listed more specifically in the section on “Dispersants” in European Patent No. A 1911814, in paragraphs

[0064] to

[0070] and

[0074] to

[0077] .

[0111] Examples of commercially available polymer dispersants are as follows: DISPERBYK is available from BYK CHEMIE GMBH. TM Dispersant; SOLSPERSE available from NOVEON TM Dispersant; TEGO™ DISPERS from EVONIK TM Dispersant; EDAPLAN from MUENZING CHEMIE TM Dispersant; ETHACRYL from LYONDELL TM Dispersant; GANEX from ISP TM Dispersant; Dispatch from CIBA SPECIALTY CHEMICALS INC. TM and EFKA TM Dispersant; Dispenser from DEUCHEM TM Dispersant; and JONCRYL from JOHNSON POLYMER TM Dispersant.

[0112] Polymerization inhibitor The radiation-curable composition may contain at least one inhibitor to improve the thermal stability of the ink.

[0113] Suitable polymerization inhibitors include phenolic antioxidants, hindered amine photostabilizers, phosphorescent antioxidants, and hydroquinone monomethyl ethers and hydroquinones commonly used in (meth)acrylate monomers. t-butylcatechol, pyrogallol, 2,6-di-tert-butyl-4-methylphenol (=BHT), and phenothiazines can also be used.

[0114] A suitable commercially available inhibitor is, for example, Sumilizer, manufactured by Sumitomo Chemical Co. Ltd. TM GA-80, Summarizer TM GM and Summarizer TM Genorad from GS;Rahn AG TM 16. Genorad TM 18 and Genorad TM 22; Irgastab from Ciba Specialty Chemicals TM UV10 and Irgastab TM UV22, Tinuvin TM 460 and CGS20; Florstab from Kromachem Ltd TMUV region (UV-1, UV-2, UV-5 and UV-8), Additol™ S region (S100, S110, S120 and) from Cytec Solvay Group S130) and PTZ.

[0115] The inhibitor is preferably a polymerizable inhibitor.

[0116] Since excessive addition of these polymerization inhibitors can reduce the curing rate, it is preferable to determine the amount that can inhibit polymerization before blending. The amount of polymerization inhibitor is preferably less than 5% by weight, more preferably less than 3% by weight, of the total radiation-curable composition.

[0117] surfactant The radiation-curable composition may contain at least one surfactant, but preferably no surfactant is present.

[0118] The surfactant can be anionic, cationic, nonionic, or amphoteric, and is usually added in a total amount of less than 1% by weight based on the total weight of the radiation-curable inkjet ink.

[0119] Suitable surfactants include fluorinated surfactants, fatty acid salts and ester salts of higher alcohols, alkylbenzene sulfonate salts, sulfosuccinate ester salts and phosphate ester salts of higher alcohols (e.g., sodium dodecylbenzenesulfonate and sodium dioctyl sulfosuccinate), ethylene oxide adducts of higher alcohols, ethylene oxide adducts of alkylphenols, ethylene oxide adducts of polyhydric alcohol fatty acid esters, and acetylene glycol and its ethylene oxide adducts (e.g., polyoxyethylene nonylphenyl ether and SURFYNOL available from AIR PRODUCTS & CHEMICALS INC). TM This includes 104, 104H, 440, 465, and TG.

[0120] Preferred surfactants are selected from fluorinated surfactants (such as fluorinated hydrocarbons) and silicone surfactants. Silicone surfactants are preferably siloxanes, which may be alkoxylated, polyether-modified, polyether-modified hydroxyl-functional, amine-modified, epoxy-modified, or otherwise modified or in combination thereof. Preferred siloxanes are polymeric, such as polydimethylsiloxanes.

[0121] Preferred commercially available silicone surfactants include BYK from BYK Chemie. TM 333 and BYK TM This includes the UV3510 and the Tego Rad 2100 from Evonik Industries.

[0122] Preferably, the surfactant is present in the radiation-curable inkjet ink in an amount of 0 to 0.1% by weight based on the total weight of the radiation-curable inkjet ink.

[0123] Flame retardant The radiation-curable composition may contain at least one flame retardant, but preferably it does not contain any flame retardants.

[0124] Preferred flame retardants include inorganic flame retardants such as alumina trihydrate and boehmite, as well as organic phosphates (e.g., triphenyl phosphate (TPP), resorcinol bis(diphenyl phosphate) (RDP), bisphenol A diphenyl phosphate (BADP), and tricresyl phosphate (TCP)); and organic phosphonates (e.g., dimethylmethylphosphonate (DM)). MP)); and organic phosphorescent compounds such as organic phosphinates (e.g., aluminum dimethyl phosphinate).

[0125] Other preferred organophosphor compounds are disclosed in U.S. Patent No. 8,273,805.

[0126] Manufacturing methods for plated products A method for manufacturing plated products according to the present invention is: -By printing the above radiation-curable composition onto the substrate and curing it, a protective area is formed on the substrate; -Plate the unprotected areas of the substrate; - Remove the hardened radiation-curable composition at least partially from the protected area of ​​the substrate. Includes stages.

[0127] In metal plating, a thin layer of metal is deposited onto the surface of a substrate.

[0128] A plating resist is applied to the surface of the substrate by applying the above-mentioned radiation-curable composition to the surface and curing it, thereby forming a protective region on the surface of the substrate. A metal is then plated onto the unprotected region of the substrate. After plating, the cured radiation-curable composition is then removed from the protective region of the substrate, at least partially.

[0129] In a preferred embodiment, a solution having a pH between 0.5 and 6.5, more preferably between 3.5 and 6.5, is used in the plating step.

[0130] Curing is preferably carried out using UV light.

[0131] Printing is preferably done by inkjet printing.

[0132] The peeling step, which removes at least partially the hardened radiation-curable composition, is performed in an alkaline solution.

[0133] The thickness of the protective area, i.e., the printed and cured ink layer, is preferably between 5 μm and 50 μm, more preferably between 10 μm and 40 μm, and most preferably between 15 μm and 30 μm.

[0134] In particular, it was observed that relatively thick protective regions could exhibit improved ENIG resistance due to the ENIG method described below.

[0135] The base material can be metal or other material. Metal plating can be used to decorate objects, to inhibit corrosion, to improve solderability, to harden, to reduce friction, to improve adhesion, to alter conductivity, to improve IR reflectivity, for radiation shielding, and for other purposes.

[0136] Copper is a particularly preferred substrate.

[0137] Metal plating can be performed by electroplating or electroless plating.

[0138] Electroplating is a method that uses electric current to reduce molten metal cations, causing them to form a thin metallic coating on a substrate. The substrate acts as the cathode in this method.

[0139] Examples of metals that can be used in electroplating include copper, chromium, lead, nickel, gold, silver, tin, and zinc.

[0140] The thickness of the deposited metal layer obtained by electroplating can vary depending on the intended application and can be controlled by adjusting the concentration of the metal in the plating bath, the current density, and other factors.

[0141] Electroless plating, also known as chemical plating or autocatalytic plating, is a plating method that involves a chemical reaction in an aqueous solution without the use of external power. The aqueous solution for the electroless method contains ions of the metal to be deposited and a reducing agent, and the formula [ka] It is necessary that a chemical reaction having the following characteristics can occur.

[0142] In principle, any hydrogen-based reducing agent can be used, but the redox potential of the reducing agent half-cell must be high enough to overcome the inherent energy barrier in liquid chemistry. For example, electroless nickel plating generally uses hypophosphate as a reducing agent, while plating of other metals such as silver, gold, and copper typically uses low molecular weight aldehydes.

[0143] The main advantage of this method over electroplating is that it does not require a power source, thereby reducing manufacturing costs. The method can also plate a variety of surface shapes and forms. The disadvantages are that the plating process is usually relatively slow and it may not produce thick deposits of metal.

[0144] In a particularly preferred embodiment, the plated product is a printed circuit board (PCB).

[0145] In another particularly preferred embodiment, the plating step includes electroless nickel immersion gold (ENIG) surface finishing.

[0146] ENIG surface finish Typically, so-called surface finishes are applied to PCB substrates. Such PCB surface finishes form a critical interface between the components and the PCB. The finish protects exposed copper circuits from oxidation, extends the lifespan of the PCB, and provides a solderable surface when assembling (soldering) components onto the PCB.

[0147] Several surface finishes exist, including Hot Air Solder Leveling (HASL), tin dipping, silver dipping, electrolytic gold, organic solderability preservative (OSP), electroless nickel dipping gold (ENIG), and electroless nickel dipping gold (electroless palladium dipping).

[0148] ENIG has become the most popular surface finish because it is the answer to major industrial trends such as the need for lead-free materials and the increasing number of complex surface parts requiring flat surfaces.

[0149] ENIG is a two-layer metallic coating of 2-8 μm gold on 7-240 μm nickel.

[0150] The nickel coating acts as a barrier to the copper, and it is the surface to which the components are actually soldered.

[0151] The gold coating protects the nickel coating during storage and also provides the low contact resistance necessary for thin gold deposits.

[0152] Electroless nickel plating refers to the electroless plating of nickel on a palladium-catalyzed copper surface.

[0153] Electroless nickel plating is a self-catalytic reaction that deposits a flat layer of nickel-phosphorus onto a copper surface.

[0154] The method involves immersing the substrate in a bath of plating solution, where a reducing agent such as sodium hypophosphate (NaPO2H2H2O) reacts with the ions in the material to deposit a nickel alloy. Dress them.

[0155] The metallurgical properties of an alloy depend on the percentage of phosphorus, which can range from 1-4% (low phosphorus) to 5-10% (medium phosphorus) and up to 11-14% (high phosphorus). For ENIG, medium-phosphorus electroless nickel is typically used.

[0156] Before plating, the surface of the material is cleaned by applying a series of chemicals. Undesirable solids left on the surface will cause poor plating. After applying each pretreatment chemical, the surface is rinsed with water two or three times to completely remove the chemicals.

[0157] Typical cleaning solutions include acid cleaning solutions such as Proselect SF from Atotech, Ronaclean HCP208 from Dow, Cleaner 865 or Cleaner ACL from Umicore; and microetching solutions such as Microetch SF from Atotech, Macuprep G4 or G5 from Mac Dermit Enthone, or Microetch 910 from Umicore.

[0158] After cleaning and / or micro-etching the copper surface, the copper surface is then activated using a solution of a precious metal, preferably palladium chloride.

[0159] Typical palladium-activated baths include AuNiACT from Atotech, Ronamerse SMT catalyst CF from DOW, Planar pre-initiator from Mac Dermit Enthone, or Accemulta MNK 4, Accemulta MFD 5, and Activator 915 and Activator KAT 451, all available from Umicore.

[0160] Electroless nickel deposition is performed in nickel plating baths such as AuNiEN (available from Atotech), Duraposit SMT820 (available from DOW), Planar Ni part DF (available from Mac Dermit Enthone), or NDF-2, Nimuden NPR 4, and Nimuden NPR8 version 2 (all available from Umicore).

[0161] The immersion gold method is based on the oxidation (removal) of nickel and the reduction (adhesion) of gold ions from the bath. Just as plating is not a self-catalytic method, it is not self-catalytic, so only the top layer of the Ni coating is replaced by gold.

[0162] This immersion gold method uses AuNic IG plus, available from Atotech. This is done in gold baths such as Aurolectroless SMT520 (available from), Planar immersion gold (available from Mac Dermit Enthone), or THP-14 (available from Umicore), Gobright TCL61, Gobright TAM 55, and Gobright TLA77.

[0163] Thus, the ENIG method consists of various stages such as cleaning, etching, activation, plating, and immersion. All of these stages, using specialized baths, are performed at various times and temperatures. For example, the pH of the various baths can range from 0.5 (palladium activation bath) to 5.5 (gold immersion bath), and a temperature of 85°C is used for nickel plating and gold immersion.

[0164] The numerous steps required to perform the ENIG method mean that the total time of the method can exceed one hour.

[0165] The protective area on the PCB formed by the plating resist must withstand these harsh conditions of the ENIG process. For example, the protective area must not be removed during the ENIG process. In particular, gold immersion treatment using a bath with a relatively high pH (between 3.5 and 6.5) has been observed to be a harsh treatment for protecting the ink layer.

[0166] However, after the completion of the ENIG process, the protected area is removed from the substrate, at least partially, in a so-called stripping bath.

[0167] Removal of etch resist or plating resist After plating, the hardened radiation-curable composition must be removed from the surface, at least partially. In a preferred embodiment, the hardened radiation-curable composition is completely removed from the surface.

[0168] The hardened radiation composition can be removed by peeling or solubilizing it.

[0169] The hardened radiation-curable composition according to the present invention is removed by an alkaline solution called a stripping bath.

[0170] Such alkaline stripping baths are typically aqueous solutions having a pH between 8 and 14, preferably higher than 9, more preferably higher than 10, and most preferably higher than 11.

[0171] Inkjet printing machine Radiation-curable inkjet ink can be ejected by one or more printheads that eject small droplets via nozzles in a controlled manner onto a substrate that is moving relative to the printhead.

[0172] For inkjet printing systems, a piezoelectric printhead is preferred. Piezoelectric inkjet printing is based on the movement of a piezoelectric ceramic transducer when voltage is applied to it. The application of voltage changes the shape of the piezoelectric ceramic transducer in the printhead, creating a void that is then filled with ink. When the voltage is removed again, the ceramic expands back to its original shape, ejecting ink droplets from the printhead.

[0173] However, the inkjet printing method according to the present invention is not limited to piezoelectric inkjet printing. Other inkjet printheads can be used, including various types such as continuous type.

[0174] Inkjet printheads typically move laterally across the surface of the ink receptors. The printhead scans back and forth. In most cases, the inkjet printhead does not print on the return path. Two-way printing is preferred to obtain higher throughput. Another preferred printing method is the "single-pass printing process," which can be performed using an inkjet printhead the width of the page or multiple staggered inkjet printheads that cover the entire width of the ink-receptor surface. In single-pass printing, the inkjet printhead usually remains stationary, and the ink-receptor surface is transported beneath the inkjet printhead.

[0175] curing equipment Radiation-curable inkjet inks can be cured by exposure to electron beams or chemical beams such as ultraviolet light. Preferably, radiation-curable inkjet inks are cured by ultraviolet light, more preferably by UV LED curing.

[0176] In inkjet printing, a curing means can be positioned in combination with the print head of an inkjet printer, moved together with it, and exposed to curing radiation immediately after the curing liquid is sprayed.

[0177] In such configurations, providing a radiation source small enough to be connected to and move with the print head can be difficult, except for UV LEDs. Therefore, a stationary, fixed radiation source, such as a curing UV light source, can be used, connected to the radiation source by flexible radiation-conducting means such as a fiber optic bundle or an internally reflective flexible tube.

[0178] Alternatively, chemical rays can be supplied from a stationary source to the radiation head by an arrangement of mirrors, including a mirror on the radiation head.

[0179] The radiation source can also be a long radiation source that extends laterally across the substrate to be cured. It can be adjacent to the transverse path of the print head so that a continuous sequence of images formed by the print head passes beneath the radiation source in steps or continuously.

[0180] Any ultraviolet light source, such as high or low-pressure mercury lamps, cold cathode tubes, black lights, ultraviolet LEDs, ultraviolet lasers, and flashlights, can be used as a radiation source, as long as a portion of the emitted light can be absorbed by a photoinitiator or photoinitiator system. Among these, preferred sources exhibit relatively long-wavelength UV contribution with a dominant wavelength of 300-400 nm. In particular, UV-A light sources are preferred because they reduce light scattering and produce more effective internal curing.

[0181] UV rays are generally classified as UV-A, UV-B, and UV-C as follows: ● UV-A: 400nm to 320nm ● UV-B: 320nm to 290nm ● UV-C: 290nm to 100nm

[0182] In a preferred embodiment, the radiation-curable inkjet ink is cured by UV LEDs. Preferably, the inkjet printing apparatus includes one or more UV LEDs having wavelengths longer than 360 nm, preferably one or more UV LEDs having wavelengths longer than 380 nm, and most preferably UV LEDs having wavelengths of about 395 nm. .

[0183] Furthermore, it is possible to cure the ink image using two light sources with different wavelengths or illuminances, either continuously or simultaneously. For example, the first UV source can be selected to be rich in UV-C, particularly in the 260nm-200nm region. The second UV source can then be rich in UV-A, and may be, for example, a gallium-doped lamp, or it may be a lamp with high levels of both UV-A and UV-B. The use of two UV sources has been found to have advantages, such as a fast curing speed and a high degree of curing.

[0184] To facilitate curing, inkjet printing systems often include one or more oxygen depletion devices. These oxygen depletion devices use a blanket of nitrogen or another relatively inert gas (e.g., CO2) in an adjustable position and adjustable inactivation to reduce the oxygen concentration in the curing environment. The gases are arranged according to their concentration. Residual oxygen levels are usually kept low, such as 200 ppm, but are generally within the range of 200 ppm to 1200 ppm.

[0185] To further enhance curing, a thermal step can be applied to the protective layer after the UV curing step. [Modes for carrying out the invention]

[0186] Examples material All materials used in the following examples were readily available from standard sources such as ALDRICH CHEMICAL Co. (Belgium) and ACROS (Belgium), unless otherwise noted. Deionized water was used.

[0187] ACMO is acryloylmorpholine available from Rahn.

[0188] CEA 70LS is a 2-carboxyethyl acrylate available from Miwon Specialty Chemical Co. as Miramer CEA.

[0189] CN146 is an acidic monofunctional acrylic oligomer available from Arkema.

[0190] AAG is high-purity acrylic acid available from BASF SE. It is Glacial.

[0191] NPG-HPD is from Arkema to Sartomer TM This is neopentyl glycol hydroxypivalate diacrylate, available as SR606A.

[0192] ITX is a Speedcure from Lambson. TM ITX is a mixture of isopropylthioxanthone isomers.

[0193] TPO-L is Speedcure™ TPO-L from Lambson, ethyl (2,4,6-trimethylbenzoyl)phenyl phosphinate.

[0194] EHDBA is from Rahn to Genocide TM It is 4-dimethylamine-2-ethyl-hexyl benzoate, available as EHA.

[0195] Contrast is Macrolex blue 3R supplied by Bayer AG.

[0196] INHIB is a mixture that forms a polymerization inhibitor having the composition shown in Table 4. [Table 4]

[0197] DPGDA is a dipropylene glycol available from ARKEMA as Sartomer SR508.

[0198] CupferronTM AL is aluminum N-nitrosophenylhydroxylamine from WAKO CHEMICALS.

[0199] Light Ester M 3F is a trifluoroethyl methacrylate available from KYOEISHA CHEMICAL Co.

[0200] Light Acrylate LA is a lauryl acrylate available from KYOEISHA CHEMICAL Co.

[0201] Light Acrylate SA is a stearyl acrylate available from KYOEISHA CHEMICAL Co.

[0202] Megaface RS 76 E is an oligomer containing fluoro, hydrophilic, lipophilic, and UV-reactive groups in MEK / ethyl acetate / MIBK, available from DIC Corporation.

[0203] Megaface RS 76 NS is an oligomer containing fluoro, hydrophilic, lipophilic, and UV-reactive groups in DPGDA, available from DIC Corporation.

[0204] Silmer ACR DI-1508 is a water-dispersible, bifunctional silicone acrylate prepolymer available from Siltech Corp.

[0205] Silmer ACR DI-2510 is a 100% active crosslinkable silicone acrylate prepolymer available from Siltech Corp.

[0206] Mecbrite CA-95MH is a micro-etch cleaner available from MEC Europe.

[0207] The Umicore cleaner 865 is a cleaning solution for copper surfaces available from Umicore. for this.

[0208] Accemulta MNK-4-M is a palladium catalyst for PCB applications available from Umicore.

[0209] Nimuden NPR-4 is an acid electroless nickel plating bath for PCB applications available from Umicore.

[0210] Gobright TAM-55 is an immersion gold bath for PCB applications available from Umicore.

[0211] method Pre-treatment of substrate First of all, the substrate (e.g., PCB board) was baked in an oven at 150 °C for 1 hour.

[0212] Then, the surface was treated in a rotaspray with the microetching bath Mecbrite CA-95MH to give the copper the specific roughness necessary to obtain excellent adhesion of the ink.

[0213] Approximately 1 μm of copper was removed from the substrate, which was done by spraying the microetching solution at 22 - 24 °C for 60 seconds.

[0214] Then immediately deionized water was sprayed for 90 seconds to rinse the substrate and stop the microetching.

[0215] Finally, the substrate was dried using an air stream as soon as possible to avoid the formation of copper oxide.

[0216] Inkjet printing Inkjet ink was printed onto a PCB substrate using a Microcraft MJP2013K1 printer equipped with a Konica Minolta printhead (KM1024 SHB). The ink was then printed onto the pre-treated substrate at 45°C at a resolution of 720x1440 dpi using 4 to 12 passes, achieving the desired layer thickness with pincure between 5% and 100% (UV LED, 395nm, 8W lamp output), followed by an extra pass with 100% pincure. The ink was printed only on areas that needed protection from plating, i.e., all copper areas where nickel and gold were not required. The ink was always printed on both the solder mask and the copper.

[0217] ENIG Plating First, the circuit board was immersed in a bath of acid cleaner (Umicore cleaner 865) at 40°C for 4 minutes. Then, the circuit board was removed and immersed in a rinse bath of deionized water (DW) at room temperature (RT) for 90 seconds.

[0218] Secondly, 8.5% by weight of Na2S2O8 and ±3.2% by weight of H2SO4 (98%) in water. The substrate was immersed in a micro-etching bath containing [a specific substance] at a temperature of 26-33°C for 100 seconds. The substrate was then removed and immersed in a DW rinse bath with RT for 90 seconds.

[0219] Thirdly, the substrate was immersed in a palladium activator bath (Accemulta MKN 4) at a temperature of approximately 30°C for 90 seconds. Then the substrate was removed and rinsed in a DW bath with RT for 90 seconds. I immersed it in the solution.

[0220] Next, the substrate was immersed in a nickel bath (Nimuden NPR 4) at a temperature of approximately 85°C for 35 minutes. Then, the substrate was removed and immersed in a DW rinse bath in RT for 90 seconds.

[0221] Finally, the circuit board was immersed in a gold bath (Gobright TAM 55) at a temperature of approximately 80°C for 12 minutes. Then, the circuit board was removed and immersed in a DW rinse bath in RT for 90 seconds.

[0222] Peeling After the plating process, the ink was removed by spraying a 5% NaOH stripping solution. Stripping was achieved by spraying the NaOH solution at 50°C for 1 to 5 minutes. Once the ink was thoroughly washed away, the substrate was rinsed with DW for 90 seconds.

[0223] This achieves selective ENIG, allowing the substrate to proceed to the next stage of PCB manufacturing.

[0224] ENIG resistance The ENIG resistance of printed inkjet inks was evaluated using a score from 0 (excellent) to 4 (poor): A value of 0 means there is no damage to the ink layer. A value of 1 means that bubbles exist beneath the undamaged ink layer. 2 means partial removal of the ink layer. 3 means complete removal of the ink layer.

[0225] Peeling The peeling pattern of the printed inkjet ink was visually evaluated using the following scoring system: + means that the ink was completely removed after peeling. - indicates that the ink is not removed or is only partially removed after peeling. [Examples]

[0226] Comparative and the radiation-curable compositions COMP-01 and INV-01 to INV-06 of the present invention were prepared according to Table 5. All weight percentages (wt%) are based on the total weight of the radiation-curable compositions. [Table 5-1]

[0227]

Table 5-2

[0228] The radiation curable composition was printed and cured as described above. Pin curing was performed at 5% lamp output between each pass, and the ENIG resistance and peelability evaluated as described above for samples that had undergone a 100% cure pass are summarized in Table 6.

Table 6

[0229] From Table 6, it becomes clear that the radiation curable composition according to the present invention functions sufficiently in the ENIG method.

Example

[0230] This example shows the influence of the thickness of the ink layer on ENIG resistance.

[0231] The UV curable inkjet ink of Example 1 was printed in various passes as described above, but this time at a resolution of 720x1440 dpi. Four passes correspond to a thickness between 5 μm and 10 μm, and eight passes correspond to a thickness between 15 μm and 20 μm.

[0232] The ENIG resistance and peelability evaluated as described above are summarized in Table 7.

Table 7

[0233] From Table 7, it becomes clear that the ENIG resistance of the ink layer with eight passes is more excellent compared to the ENIG resistance of the ink layer with four passes. The peelability of both layers is sufficient.

Example

[0234] This embodiment demonstrates the effect of ink layer thickness on ENIG resistance and delamination on PCB substrates with high pore size or a wide variety of surface shapes.

[0235] Radiation-curable compositions INV-07 and INV-08 according to the present invention were prepared according to Table 8. All weight percentages (wt%) are based on the total weight of the radiation-curable compositions. [Table 8]

[0236] Layers of UV-curable inkjet inks INV-07 and INV-08 with different thicknesses were printed as described above. Eight passes correspond to a thickness between 15 μm and 20 μm, and twelve passes correspond to a thickness between 25 μm and 30 μm.

[0237] The ENIG resistance and peelability, as evaluated above, are summarized in Table 9. [Table 9]

[0238] Table 9 clearly shows that the ENIG resistance of the ink layer that passed through 12 times is superior to that of the ink layer that passed through 8 times. The peelability of both layers is sufficient.

Claims

1. a. 3-10% by weight of a photoinitiator; b. 20–40% by weight of a compound having a chemical structure according to formula I. 【Chemistry 1】 [In the formula, R 1 This indicates a hydrogen or methyl group. R 2 and R 3 This represents hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkaryl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. R 2 and R 3 This can indicate the atoms necessary for the formation of a 5- to 8-membered ring. c. 1-25% by weight of a monofunctional (meth)acrylate containing a carboxylic acid group, a phosphate group, or a phosphonic acid group; d. 30-50% by weight of polyfunctional (meth)acrylate A radiation-curable inkjet ink containing, where all weight percents are relative to the total weight of the inkjet ink, The radiation-curable inkjet ink further contains at least 0.1% by weight of a liquid penetration control monomer selected from the group consisting of C6-C22 alkyl (meth)acrylate, fluorinated (meth)acrylate, and silicone (meth)acrylate, and the radiation-curable inkjet ink is 1000s -1 It is characterized by having a viscosity between 4 and 14 mPa·s at a shear rate of 45°C, and having a liquid permeability control monomer content between 0.1% and 10% by weight. Radiation-curable inkjet ink.

2. The amount of liquid penetration control monomer is at least 1 / 1 by weight relative to the total weight of the inkjet ink. A radiation-curable inkjet ink according to claim 1, wherein the amount is %.

3. The radiation-curable inkjet ink according to claim 1 or 2, wherein the liquid penetration control monomer is selected from fluorinated acrylates and silicone acrylates.

4. The radiation-curable inkjet ink according to claim 1 or 2, wherein the compound having a chemical structure according to formula I is acryloylmorpholine.

5. A radiation-curable inkjet ink according to claim 1 or 2, wherein the monofunctional (meth)acrylate containing a carboxylic acid group, a phosphoric acid group, or a phosphonic acid group is selected from the group consisting of acrylic acid, 2-carboxyethyl acrylate, 2-acryloylethyl succinate, and 2-hydroxyethyl methacrylate phosphate.

6. A radiation-curable inkjet ink according to claim 1 or 2, wherein the polyfunctional (meth)acrylate is selected from the group consisting of dipropylene glycol diacrylate, neopentyl glycol diacrylate, neopentyl glycol (2x propoxylated) diacrylate, pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, tripropylene glycol diacrylate, ditrimethyloylpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, neopentyl glycol hydroxypivalate diacrylate, and polyethylene glycol diacrylate.

7. - A protective area is formed on the substrate by printing and curing a radiation-curable inkjet ink according to any one of claims 1 to 6 onto the substrate; - Plating the unprotected areas of the substrate; - Remove the hardened radiation-curable inkjet ink from the protected area of ​​the substrate, at least partially. A method for manufacturing plated products, including a multi-stage process.

8. A method for manufacturing a plated product according to claim 7, wherein a solution having a pH between 3.5 and 6.5 is used in the plating stage.

9. A method for manufacturing a plated product according to claim 7 or 8, wherein the base material is copper.

10. A method for manufacturing a plated product according to claim 7 or 8, wherein the plated product is a printed circuit board (PCB).

11. A method for manufacturing a plated product according to claim 7 or 8, wherein the plating step includes electroless nickel immersion gold (ENIG) surface finishing.

12. The method according to claim 7 or 8, wherein curing is performed using UV rays.

13. The method according to any one of claims 7 to 12, wherein the peeling step is performed in an alkaline solution.

14. The method according to any one of claims 7 to 13, wherein the thickness of the protective area is at least 15 μm.

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