JP-7856609-B2 - Radiation-curable compositions for plating applications

Inventors

• アンドレ，ロマーヌ
• コルテス・サラザール，フェルナンド
• レンズ，マルク
• ファン・アールト，フベルトゥス
• ロキュフィエ，ヨハン

Assignees

• アグフア－ゲヴエルト，ナームローゼ・フエンノートシヤツプ

Dates

Publication Date

20260511

Application Date

20230818

Priority Date

20190826

Claims (14)

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. [In the formula, R1 represents a hydrogen or methyl group. R2 and R3 represent 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. R2 and R3 can represent 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. A radiation-curable inkjet ink containing 30-50% by weight of a polyfunctional (meth)acrylate, where all weight percentages are relative to the total weight of the inkjet ink. A radiation-curable inkjet ink characterized in that 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, the radiation-curable inkjet ink has a viscosity between 4 and 14 mPa·s at 45°C at a shear rate of 1000 s⁻¹ , and the content of the liquid penetration control monomer is between 0.1% by weight and 10% by weight.
2. The radiation-curable inkjet ink according to claim 1, wherein the amount of liquid penetration control monomer is at least 1% by weight relative to the total weight of the inkjet ink.
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. The radiation-curable inkjet ink according to claim 1 or 2, wherein the monofunctional (meth)acrylate containing a carboxylic acid group, a phosphate 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. The 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; A method for manufacturing a plated product, comprising the step of at least partially peeling off a cured radiation-curable inkjet ink from a protective area of a substrate.
8. A method for manufacturing a plated product according to claim 7, using a solution having a pH between 3.5 and 6.5 during 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.

Description

Technical field of the invention : The present invention relates to radiation-curable compositions, preferably UV-curable inkjet inks, for use in various plating applications, such as those used in PCB manufacturing. Background Technology for the Invention: The manufacturing workflow for printed circuit boards (PCBs) is gradually shifting from standard workflows to digital workflows in order to reduce the number of process steps and lower the cost and environmental impact of PCB manufacturing. Digital workflows further allow for the possibility of short-term manufacturing or even individual part manufacturing without significantly increasing costs. Thus, moving from analog workflows to digital workflows has clear economic and environmental benefits. Inkjet printing has been proposed as one of the preferred digital manufacturing methods for various stages of PCB manufacturing, progressing from etch resist to solder mask and then to legend printing. The preferred inkjet ink is a UV-curable inkjet ink. In PCB manufacturing, several plating methods are used, such as copper plating, nickel plating, and gold plating. ENIG (electroless nickel-metal immersion) plating is a surface finishing method commonly used in PCB manufacturing. The ENIG method involves depositing thin layers of nickel and gold onto exposed copper areas within a PCB to provide excellent solderability and superior protection against oxidation. 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. 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 deposited only on the exposed copper areas, and finally, the protective layer must be removed (stripped) to obtain the final substrate. When using inkjet ink as an etching resist, solder mask, legend ink, or plating resist, 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. When used as a plating resist in the ENIG process, the challenge for the protective layer is that it must withstand the various conditions (pH, temperature) used during the ENIG process while being completely removed during the stripping stage. 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% by weight of acrylamide; 20 to 75% by weight of polyfunctional acrylate; and 1 to 15% by weight of 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) in relation to the production of embossed portions for decorative purposes, and in Patent Document 3 (Agfa Gevaert NV) in relation to 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 acidic etching steps (pH less than 3) followed by a medium to strong alkaline stripping step. To expand the range of applications for inkjet printing in PCB manufacturing, inkjet inks that function effectively as plating resists, particularly in the ENIG plating process, are needed. This study found that a radiation-curable composition according to the present invention can achieve the objectives of the present invention. International Publication No. 2016/050504 BrochureInternational Publication No. 2016/050372 BrochureInternational Publication No. 2016/050371 brochure ExamplesMaterials: Unless otherwise noted, all materials used in the following examples were readily available from standard sources such as ALDRICH CHEMICAL Co. (Belgium) and ACROS (Belgium). Deionized water was used. ACMO is acryloylmorpholine available from Rahn. CEA 70LS is a 2-carboxyethyl acrylate available from Miwon Specialty Chemical Co. as Miramer CEA. CN146 is an acidic monofunctional acrylic oligomer available from Arkema. AAG is high-purity acrylic acid available from BASF SE. It is Glacial. NPG-HPD is a neopentyl glycol hydroxypivalate diacrylate available from Arkema as Sartomer ™ SR606A. ITX is a mixture of isopropylthioxanthone isomers, Speedcure ™ ITX from Lambson. TPO-L is Speedcure™ TPO-L from L