Method for manufacturing an etch resist pattern on a metal surface

Abstract

To provide a method for producing an etch resist pattern on a metallic surface.SOLUTION: A method includes applying a first liquid composition comprising a first reactive component onto a metallic surface to form a primer layer, and applying a second liquid composition comprising a second reactive component on the primer layer by image-wise printing by a nonimpact printing process to produce an etch-resist mask according to a predetermined pattern. When droplets of the second liquid composition contact the primer layer, the second reactive components causes a chemical reaction with the first reactive components so as to immobilize the droplets.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to the manufacture of conductive patterns on a metal surface, such as on a printed circuit board (PCB), by directly applying an etch resist mask onto the metal layer.

Background Art

[0002] Printed circuit boards (PCBs) are widely used in most electronic products. The manufacture of PCBs is considered to be less expensive, faster, and more accurate than when using other wiring methods such as point-to-point configurations. Nevertheless, there is a continuing search for simpler and more cost-effective manufacturing processes that enable the production of PCBs that meet specific requirements, including maintaining high quality, cost-effective small batches, higher throughput large batches, on-demand substrates, substrates with higher density wiring, substrates with finer lines, and other manufacturing.

[0003] In the manufacture of a PCB, wiring patterning is usually performed by a subtractive method that involves removing copper from a copper layer laminated on an insulating material substrate and leaving only the desired copper wires (also called patterns or images) as conductive paths. This process involves applying an etch resist mask on the copper layer and removing the exposed copper portions by an etching process. In the currently used method for creating the etch resist mask, a photosensitive etch resist material (generally a UV-sensitive material) is applied to the copper layer, a photomask is created using a photoplotter or a laser plotter, etc., the layer is exposed to UV rays, the exposed areas are cured and fixed as a pattern on the copper layer, and the unexposed etch resist is removed by chemical development. Thus, it becomes possible to form a wiring pattern by etching the unmasked copper portions and then by a stripe formation process for removing the etch resist mask. The wiring pattern covers about 25% of the surface of the substrate. However, during manufacturing, the entire substrate is coated with the photosensitive etch resist material, followed by exposure of the wiring pattern to UV or other radiation to form the etch resist mask. The remaining photosensitive etch resist material is washed away.

[0004] The etch resist pattern can also be applied by an additive method, for example, by non-impact printing (e.g., inkjet printing) on a copper layer. Conventional inkjet materials have a relatively low viscosity, and thus when ink droplets hit a non-absorbent surface such as a copper surface, usually, along with uncontrolled droplet spreading, other phenomena such as clustering, ink coalescence, and extensive dot gain occur. Therefore, the printed pattern may have reduced resolution, insufficient details, non-uniform pattern line widths, insufficient line edge smoothness, and may cause short circuits between adjacent conductive lines and breaks in the pattern lines. Summary of the Invention Means for Solving the Problems

[0005] Embodiments of the present invention relate to a method of forming or applying an etch resist mask on a metal layer by non-impact printing. The method includes applying a first liquid composition containing a first reactive component onto a metal surface to form a primer layer, and applying a second liquid composition containing a second reactive component onto the primer layer by imagewise (as intended image) printing by a non-impact printing process to generate an etch resist mask according to a predetermined pattern, wherein when droplets of the second liquid composition contact the primer layer, the second reactive component may be characterized by undergoing a chemical reaction with the first reactive component to immobilize the droplets.

[0006] Embodiments of the present invention relate to a two-component ink composition set for applying an etch resist mask on a metal layer. The set includes a first liquid composition containing an immobilizing reactive component and a second liquid composition containing an etch resist reactive component, and the immobilizing reactive component and the immobilizing reactive component can be characterized by undergoing a chemical reaction to form a two-component material insoluble in water and an acidic etch solution.

[0007] The subject matter regarded as the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, the present invention can be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings in regard to both its construction and method of operation, together with its objects, features, and advantages.

[0008] It should be understood that, for the sake of brevity and clarity, the elements shown in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Further, where appropriate, the same reference numerals may be used in multiple drawings to indicate corresponding or similar elements.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

[0010] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific examples. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

[0011] Embodiments of the present invention relate to a method of forming or applying an etch resist mask on a metal layer by non-impact printing such as inkjet printing. Embodiments of this method are applicable, for example, to the manufacture of printed circuit boards (PCBs). In the method of applying an etch resist mask on a metal surface according to an embodiment of the present invention, a first liquid composition containing a first reactive component is applied to the surface to form a primer layer, and then a second liquid composition containing a second reactive component is printed on the primer layer to generate an etch resist mask according to a predetermined pattern. According to an embodiment of the present invention, the second reactive component undergoes a chemical reaction with the first reactive component to generate a two-component material that is insoluble in water and an etching solution. The two-component material has a high viscosity due to each component, and the reaction causes the droplets of the second composition to be immobilized when they hit the primer layer.

[0012] The metal layer may be a copper layer laminated on an insulating non-conductive substrate. For ease of explanation, the form of the metal layer surface is referred to in the following description. However, it should be understood that other metal surfaces such as an aluminum surface, a stainless steel surface, and a gold surface are also applicable to embodiments of the present invention.

[0013] According to an embodiment of the present invention, an etch resist mask can be formed by continuously applying two liquid compositions containing reactive components on a metal layer, each of which can chemically react with another reactive component contained in another composition. The product of the chemical reaction is called a two-component material. Each of the two compositions is water-soluble, and the two-component reaction product material is water-insoluble and etch solution-insoluble. That is, the two-component reaction product material is neither water-soluble nor soluble in the etch solution used to etch the metal layer. According to some embodiments, the etch solution can be an acidic etch solution such as, for example, a copper chloride and hydrogen peroxide mixture.

[0014] According to some embodiments, at least one of the compositions can contain two or more reactive components that can chemically react with one or more reactive components in the other composition. According to an embodiment of the present invention, one of the compositions can contain polyvalent and / or polycationic groups and / or polyvalent inorganic cations and can function as an immobilized composition. The other composition can contain polyanionic groups and can function as an etch resist composition. In some embodiments, it is not necessary to remove the layer containing the immobilized composition before the etching process, and this layer is removed during the etching process.

[0015] For example, examples of the immobilized reactive component include, but are not limited to, polyethyleneimine, divalent salts, heteropolymers of vinyl pyrrolidone, and the like.

[0016] According to an embodiment of the present invention, the first composition can be applied on a copper surface either as a uniform layer or an image-like layer by inkjet printing or any other printing or coating method. The second composition is printed by inkjet printing, for example, to form a desired wiring pattern using a non-impact printing method. When the droplets of the second composition hit the primer layer on the metal surface, a chemical reaction occurring between two reactive components (i.e., polyvalent and / or polycation or polyvalent cation reacting with polyanion) causes an instantaneous and relatively large increase in the viscosity of the second composition, preventing uncontrolled spreading of the droplets. The droplets are immobilized or frozen without spreading on the surface. According to an embodiment of the present invention, the reactive component of the first composition can be an immobilization component that chemically immobilizes the printed pattern to the substrate when reacting with the second component of the second composition. The reactive component of the second composition can be an etch resist component. Such a component can include, for example, an acid-etched resistant substance that prohibits acid etching. In some embodiments, the immobilization component can adhere to the metal layer to ensure remaining attached to the metal layer of the etch resist mask during the etching process. According to other embodiments, the reactive component of the first composition can be an etch resist component, and the reactive component of the second composition can be an immobilization component.

[0017] The composition containing the immobilization component is applied on the metal surface as a primer layer and can form a uniform or patterned layer using non-impact printing or any other known coating method. The composition containing the etch resist component can then be applied image-wise by non-impact printing to form an etch resist mask. In some embodiments, an acid solution can be added to the first composition to activate the immobilization material.

[0018] Alternatively, according to some embodiments of the present invention, a composition comprising an etch resist component is applied onto a metal surface as a primer layer and a uniform or patterned layer is formed using non-impact printing or any other known method. Subsequently, a composition comprising an immobilization component can be applied imagewise by non-impact printing to form an etch resist mask. For ease of explanation, in the following description, reference is mainly made to embodiments in which the immobilization composition is applied directly onto the metal surface and the etch resist composition is deposited onto the layer of immobilized material formed. However, it should be understood that the following description can also be applied to embodiments in which the order of depositing the compositions is reversed.

[0019] Some embodiments of the present invention relate to a two-component ink composition set for applying an etch resist mask onto a metal surface. The set includes two solutions (e.g., two aqueous solutions) stored in different containers, the first solution may include an immobilization component, and the second solution may include an etch resist component. The immobilization component in the first solution and the etch resist component in the second solution can react with each other to form an etch resist-insoluble composition that is not water-soluble and not soluble in an etching solution and has good adhesion to a metal such as copper.

[0020] Referring to FIG. 1, which is a flowchart of a method for manufacturing a conductive pattern according to some embodiments of the present invention, and also referring to FIG. 2, which shows the form of the process of FIG. 1. According to some embodiments of the present invention, this method may include the step of forming a primer layer on a metal surface, as shown in box 110. The primer layer (e.g., layer 230 in FIG. 2) can be formed by applying a first liquid composition containing a first reactive component onto a metal surface (e.g., surface 220 in FIG. 2) laminated on an electrically insulating substrate (e.g., substrate 210 in FIG. 2). The reactive component of the first composition can be a water-soluble immobilized component and can include reactive cationic groups, such as polycations or polyvalent cations. The cationic reactive component can adhere to a metal surface such as a copper surface. In some embodiments, the application of the first liquid composition can be performed by any industrial coating method.

[0021] Examples of cationic reactive components include, but are not limited to, polyamides such as polyethyleneimine, polyquaternary amines, long-chain quaternary amines, polytertiary amines at various pH levels, and polyvalent inorganic cations such as magnesium cations, zinc cations, calcium cations, copper cations, ferric and ferrous cations. The polymer component can be introduced into the formulation either as a soluble component or in the form of an emulsion. The primer layer can be applied to the metal surface using any suitable printing or coating method, such as inkjet printing, spraying, metering rod coating, roll coating, dip coating, etc. The primer layer can be uniform or patterned.

[0022] In some embodiments, the primer layer may be a continuous layer that substantially covers the entire metal surface. Alternatively, the primer layer may be printed in an image-like manner according to the required pattern. The pattern can be applied by non-impact printing, such as inkjet printing. The required pattern can be, for example, the copper wiring of a PCB.

[0023] As shown in Box 120, in some embodiments, the method may include printing a second liquid composition comprising a second reactive component onto the primer layer by a non-impact printing process. The printing may be performed in an image-like manner, for example, using an inkjet printer, to form an etch resist mask on the metal surface according to a predetermined pattern. During the printing process of the second liquid, the metal surface can be heated to a high temperature to further improve the printing quality. A typical surface temperature range is from 25°C to 80°C. The second liquid composition can include a second reactive component that, when contacting or hitting the primer layer, can chemically react with the first reactive component contained in the primer layer to immobilize the droplets of the second composition. The product of the chemical reaction is a material that has a substantially higher viscosity than each of the first and second compositions and is insoluble in both water and the etching solution. The insoluble etch resist pattern can have a dry layer thickness of at least 0.01 μm. In some embodiments, the thickness of the printed pattern can be up to 12 μm.

[0024] In some embodiments, the reactive component of the second composition may be water-soluble and may contain reactive anion groups. Examples of anionic reactive components can include, but are not limited to, at least one anionic polymer (basic) at a pH higher than 7.0. The anionic polymers can be selected from acrylic resins and styrene-acrylic resins in the form of their dissolved salts. The anionic polymers can be selected from sulfone resins in the form of their dissolved salts, such as sodium, ammonium or amine-neutralized forms, and sulfone resins in the form of polymer emulsions or dispersions. The polymer component can be introduced into the formulation either as a soluble component or in the form of an emulsion. Alternatively, in some embodiments, the method can include applying an etch resist composition to form the primer layer, and the second layer can be formed by printing an immobilizing composition in an image-like pattern using a non-impact printing method.

[0025] As shown in Box 130, in some embodiments, the method includes removing the exposed or unmasked portion of the primer layer, and the layer to be removed may be an immobilization layer containing a cationic component, or in other embodiments, an etch resist layer containing a polyanionic reactive component. When the first layer is an immobilization layer, in some embodiments, the immobilization composition can be washed away during the etching process. The exposed portion of the first layer may mainly contain reactive components and can be easily washed away simply by immersing the substrate in water, while the etch resist mask formed by the chemical reaction of the first and second reactive materials is insoluble and remains attached to the metal surface.

[0026] As shown in Box 140, embodiments of the method may include etching the metal surface. For example, a masked copper plate can be etched with a copper etching (e.g., acidic copper etching) solution to remove the unmasked copper portions. As shown in Box 150, the etch resist mask is then removed. For example, in PCB manufacturing, when the etch resist mask is removed, a predetermined wiring pattern of conductive copper lines attached to the surface of the insulating substrate 210 can appear.

Example

[0027] Using an Epson Stylus (registered trademark) 4900 inkjet printer, an exemplary etch resist composition (the second composition described herein) was printed onto FR4 copper clad substrates having thicknesses of 1 / 2 Oz (about 17.5 μm), 1 / 3 Oz (about 11.7 μm), and 1 Oz (about 35 μm). In some cases, a fixation composition (the first composition described herein) was first applied to the copper using an Epson Stylus (registered trademark) 4900 inkjet printer, and the etch resist composition was selectively printed thereon according to a predetermined pattern. In the following description, %(w / w) is a measure of the concentration of a substance in weight % relative to the weight of the composition. Using an etchant bath containing a 42 Baumé ferric chloride (II) etchant solution supplied by Amza [pernix 166] (trademark), the copper not protected by the regions exposed by the etch resist was etched away. The etching was carried out at a temperature of 35 °C for 3 minutes in a Spray Developer S31 (trademark) supplied by Walter Lemmen GMBH. The etch resist mask was removed by immersing it in a 1% (w / w) aqueous NaOH solution at a temperature of 25 °C, subsequently washing the FR4 copper substrate with water, and air drying it at 25 °C. In some experiments, the copper substrate was also etched using an industrial etching apparatus including a hyper and super etching apparatus having a copper chloride solution manufactured by Universal or Shmidth for etching the unprotected copper.

[0028] Example 1 - An etch resist composition (comparative data) printed on an uncoated FR4 copper substrate. The etch resist composition (second composition) was prepared using 10% propylene glycol, 1% (w / w) 2-amino-2-methylpropanol, 0.3% (w / w) BYK348 supplied by BYK, and 2% (w / w) Bayscript® BA cyan. These substances were dissolved in water containing 24% Joncryl™ 8085 styrene acrylic resin solution as an anionic reactive component. Using an Epson Stylus® 4900 inkjet printer, the etch resist composition was printed on an FR4 copper clad substrate having a thickness of 1 / 2 Oz (about 17.5 μm) to produce an etch resist mask. The thickness of the dry etch resist was 5 μm.

[0029] The etch resist mask was visually inspected, and the printed pattern showed very poor print quality, very poor line definition accuracy and line breakage, and very poor short circuits between lines.

[0030] Example 2 - The etch resist composition was prepared as detailed in Example 1. The primer or immobilization composition was prepared as a mixture of an aqueous solution of 10% n-propanol containing 10% (w / w) LUPASOL® PR8515 from BASF (polyethyleneimine as a cationic reactive component), 10% (w / w) propylene glycol, and 0.3% (w / w) TEGO 500 from Evonik Industries (foam suppression substrate wetting additive).

[0031] Using an Epson Stylus (registered trademark) 4900 inkjet printer, an FR4 copper substrate was coated. The coated substrate was dried at room temperature to form a completely transparent and uniform coating. The dried layer with a thickness of 0.3 μm covered the entire surface without crystal formation. Using an Epson Stylus (registered trademark) 4900 inkjet printer, an etching resist composition was printed on the coated copper substrate and dried at 80 °C to generate a two-component etch resist mask. The etch resist mask was visually inspected and showed better printing quality than that of Example 1, but it was still found to have relatively poor printing quality regarding line spread and short circuits between lines. The etching of the unmasked copper and the removal of the etch resist mask were performed as detailed in Example 1. The wiring pattern generated after the etching process had the same image as the etch resist mask with the same line spread and short circuits between lines. It should be noted that for specific applications, the printing quality as shown in Example 2 is sufficient.

[0032] Example 3 - The etching resist composition was prepared as detailed in Example 1. The immobilization composition was prepared as detailed in Example 2, except that 0.3% (w / w) of TEGO 500 was replaced with 0.3% (w / w) of TEGO 500 containing 13% (w / w) of concentrated HCl.

[0033] As detailed in Example 2, an FR4 copper plate was coated with an immobilization composition using a Pason Stylus (registered trademark) 4900 inkjet printer, and after drying, a coating layer detailed in Example 2 was formed. Similar to Example 2, an etch resist composition was inkjet printed onto the coated copper substrate and dried at 80 °C to generate a two-component etch resist mask. The etch resist pattern had sharp edges, no line breaks, a thickness up to 2 mm, and showed high print quality with clearly defined thin lines. The etching of the unmasked copper and the removal of the etch resist mask were performed as detailed in Example 1. The wiring pattern generated by the etching and stripping process showed a clearly defined pattern with sharp edges and thin lines with a width of up to 15 μm without breaks.

[0034] Example 4 - An etch resist composition printed on a copper surface coated with a reactive cationic composition containing hydrochloric acid (HCl). The etch resist composition was prepared as detailed in Example 1. The immobilization composition was prepared as a mixture of 10% (w / w) Styleze W-20 (as a 20% polymer in an aqueous solution manufactured by ISP), 0.1% BYK 348, and 13% (w / w) concentrated HCl aqueous solution.

[0035] The Mayer bar method was used to cover the F4F copper substrate with the immobilization composition to generate a dry layer with a thickness of 0.4 μm. The coated substrate was left to dry, producing a completely transparent coating without crystal formation over the entire surface of the copper. Similar to Example 2, an etch resist composition was inkjet printed onto the coated copper substrate and dried at 80 °C to generate a two-component etch resist mask.

[0036] The etch resist pattern showed high print quality, well-defined thin lines with sharp edges, no line breaks, and a thickness up to 2 mm. Residues of the immobilized layer not covered by the etch resist composition were submerged in water at a temperature of 25 °C for 2 minutes to be washed off and dried at 80 °C. The etching of the exposed copper and the removal of the etch resist mask were carried out as detailed in Example 1. The wiring pattern on the substrate showed well-defined thin lines with sharp edges, no breaks, and a width up to 2 mils (50.8 μm).

[0037] Example 5 - An etch resist composition printed on a copper surface coated with a reactive cationic composition containing hydrochloric acid (HCl). The etch resist composition was prepared as detailed in Example 1. The immobilizing composition was prepared as a mixture of 10% (w / w) Lupasol HF (56% polymer in aqueous solution, manufactured by BASF), 13% (w / w) concentrated HCl, and 0.1% BYK348 aqueous solution.

[0038] The FR4 copper substrate was coated with the immobilizing composition using the Meyer bar method to produce a dry layer with a thickness of 1 μm. The coated substrate was left dry to produce a completely transparent coating without crystal formation over the entire copper surface. Similar to Example 2, the etch resist composition was inkjet printed on the coated copper substrate and dried at 80 °C to produce a two-component etch resist mask.

[0039] The etch resist pattern showed high print quality, well-defined thin lines with sharp edges, no line breaks, and a width up to 2 mils (50.8 μm). Residues of the immobilized layer not covered by the etch resist composition were submerged in water at a temperature of 25 °C for 3 minutes to be washed off and dried at 80 °C. The etching of the exposed copper and the removal of the etch resist mask were carried out as detailed in Example 1. The wiring pattern on the substrate showed well-defined thin lines with sharp edges, no breaks, and a width up to 2 mils (50.8 μm).

[0040] Example 6 - An etch resist composition printed on a copper surface coated with a reactive cationic composition containing hydrochloric acid (HCl). The etch resist composition was prepared as detailed in Example 1. The immobilization composition was prepared as a mixture of 10% (w / w) Styleze W-20 (as a 49% polymer in an aqueous solution manufactured by BASF), 0.1% BYK 348, and 13% (w / w) concentrated HCl aqueous solution.

[0041] The FR4 copper substrate was covered with the immobilization composition using the Mayer bar method to produce a dry layer with a thickness of 0.4 μm. The coated substrate was left dry to produce a completely transparent coating without crystal formation over the entire surface of the copper. Similar to Example 2, the etch resist composition was inkjet printed on the coated copper substrate and dried at 80 °C to produce a two-component etch resist mask.

[0042] The etch resist pattern showed sharp edges and well-defined thin lines with a print quality up to 2 mm high and no line breaks. The residue of the immobilization layer was treated as detailed in Example 5. The etching of the exposed copper and the removal of the etch resist mask were carried out as detailed in Example 1. The wiring pattern on the substrate showed sharp edges and well-defined thin lines with a width up to 2 mils (50.8 μm) and no breaks.

[0043] Example 7 - An etch resist composition printed on a copper surface coated with a reactive composition containing citric acid. The etch resist composition was prepared as detailed in Example 1. The immobilization composition was prepared as a mixture of an aqueous solution containing 10% (w / w) citric acid, 25% (w / w) propylene glycol, and 0.3% (w / w) TEGO 500 (foam suppression substrate wetting additive) manufactured by Evonik Industries.

[0044] Using an Epson Stylus (registered trademark) 4900 inkjet printer, an FR4 copper substrate was coated with an immobilization composition. The coated substrate was dried at room temperature to form a completely transparent and uniform coating. The dried layer with a thickness of 0.3 μm covered the entire surface without crystal formation. Similar to Example 2, an etching resist composition was inkjet printed onto the coated copper substrate and dried at 80 °C to produce a two-component etch resist mask.

[0045] The etch resist pattern had sharp edges and showed well-defined thin lines with a width up to 2 mils (50.8 μm) and high print quality without line breaks. The etching of the exposed copper and the removal of the etch resist mask were carried out as detailed in Example 1. The wiring pattern on the substrate had sharp edges and showed well-defined thin lines with a width up to 2 mils (50.8 μm) without breaks.

[0046] Example 8 - Two-component reaction, a coating composition containing an etch resist composition was prepared as detailed in Example 1. The immobilization composition was prepared as a mixture of 2.5% (w / w) Zn(NO3)2, 3.75% (w / w) citric acid, 0.2% (w / w) Capstone 51, 5% (w / w) n-propanol, and an aqueous solution of Lupasol (trademark) FG (manufactured by BASF).

[0047] The FR4 copper substrate was covered with the immobilization composition using the Mayer bar method to produce a dried layer with a thickness of 0.5 μm. The coated substrate was left dried to produce a completely transparent coating without crystal formation over the entire copper surface. Similar to Example 2, an etch resist composition was inkjet printed onto the coated copper substrate and dried at 80 °C to produce a two-component etch resist mask.

[0048] Similar to Example 2, an etch resist composition was inkjet printed onto the coated copper substrate and dried at 80 °C to produce a two-component etch resist mask.

[0049] The etch resist pattern had sharp edges and showed well-defined thin lines with high print quality and widths up to 2 mils (50.8 μm) without line breaks. Unmasked copper etching and removal of the etch resist mask were performed as detailed in Example 1. The wiring pattern generated by the etching and stripping process had sharp edges and showed well-defined thin lines with widths up to 2 mils (50.8 μm) without breaks.

[0050] Example 9 - An etch resist composition was prepared as an aqueous solution of 8% (w / w) PVA, 24% Joncryl™ 8085 styrene acrylic resin solution (supplied as 42% polymer in aqueous solution), and 1.5% 2-amino-2-methylpropanol.

[0051] The immobilization composition was prepared from 10% (w / w) Lupasol G20 (manufactured by BASF) containing 2% (w / w) Basacid™ Red 495, 10% (w / w) propylene glycol, 10% n-propanol, 0.3% (w / w) TEGO 500, and 12% (w / w) concentrated HCl. The FR4 copper substrate was covered with the immobilization composition using the Mayer bar method to produce a dry layer with a thickness of 2.4 μm. The coated substrate was left to dry to produce a completely transparent coating without crystal formation over the entire copper surface. The immobilization composition was inkjet printed onto the coated copper substrate and dried at 80 °C to produce a two-component etch resist mask.

[0052] Similar to Example 2, the etch resist composition was inkjet printed onto the coated copper substrate and dried at 80 °C to produce a two-component etch resist mask.

[0053] The etch resist pattern showed sharp edges and well-defined thin lines with a width up to 2 mils (50.8 μm) and high print quality without line breaks. Residues of the immobilized layer not covered with the etching resist composition were immersed and washed away in an aqueous solution of 1% (w / w) NaHCO₃ at a temperature of 25 °C for 30 seconds and dried at 80 °C. The etching of the exposed copper and the removal of the etch resist mask were performed as detailed in Example 1. The wiring pattern on the substrate showed sharp edges and well-defined thin lines with a width up to 2 mils (50.8 μm) without breaks.

[0054] (Cationic composition for immobilizing reactive components) Examples of cationic reactive components (immobilized reactive components) include, but are not limited to, polyamides such as polyethyleneimine, divalent metal salts, both organic and inorganic acids, vinyl pyrrolidone, heteropolymers of dimethylaminopropyl methacrylamide, and methacryloylaminopropyl lauryldimethylammonium chloride, polyquaternary amines, and polyamines present in their natural form or as ammonium salts.

[0055] The thickness of the dried immobilized layer can be as thin as about 0.01 μm. The typical desired thickness of the dried layer can vary between 0.025 - 5 μm.

[0056] The cationic composition (first composition) can include additional components adapted to suit the application method and the desired width of the dried layer. The composition can have a viscosity suitable for spraying or inkjet printing, for example, less than 60 cP at ambient temperature, or a viscosity of 3 - 20 cP (centipoise). If different coating methods are applied, the composition can have a higher viscosity.

[0057] In some embodiments, an acidic solution can be added to the first solution to enhance the reactivity of the first layer with respect to the copper layer 320, as well as its reactivity with respect to the etching resist or the immobilization layer. In some embodiments, the first layer can be further developed, for example, with water, prior to the copper etching process. In some embodiments, the applied first layer can be dried prior to the application of the second layer. The dried layer can mainly contain the first reactive material. The first layer can be dried using any known drying method.

[0058] Some non-limiting examples of the first reactive component (e.g., immobilization component) and the first composition (e.g., immobilization composition, cationic composition) are listed in Table 1.

[0059]

Table 1

[0060] In some embodiments, the second reactive component (e.g., polymer component) can be an etch resist component (resistant to the metal etching solution). Examples of the second reactive component include polyanionic active groups (e.g., acrylate, styrene acrylate), phosphates, and sulfonates. Droplets of the etch resist ink applied on the first layer (e.g., immobilization layer) can be immobilized and fixed on the copper surface due to the chemical reaction between the first reactive material (including polycation) and the second reactive material (including polyanion). Since the immobilization is very fast (in the microsecond range), the dimensions of the printed pattern are approximately the same as those of the required pattern. The compounds formed by the reaction of the first reactive material and the second reactive material (both soluble in water) should be insoluble in the copper etch solution.

[0061] The second composition may have a viscosity suitable for inkjet printing of less than 60 cP, for example 3 to 20 cP, at the jetting temperature. If different coating methods are applied, the composition may have a higher viscosity. In some embodiments, the second composition may contain 20% (w / w) or less of reactive components to maintain the required viscosity. In some embodiments, the polyanion reactive component (etch resist polymer), when dissolved in the composition, may have a molecular weight of at most 5000 molar weight (for example, the polymer may have relatively short chains). In some embodiments, the etch resist polymer can have a higher molar weight such that a composition in the form of a polymer emulsion or dispersion is obtained. The second reactive component may have a high acid value, for example having 100 or more reactive anion groups per gram of polymer. For example, the etch resist polymer according to an embodiment of the present invention may have 200, 240, 300 or more reactive anion groups per chain.

[0062] Some non-limiting examples of the second reactive component (etch resist component) and the second composition (etch resist composition, anionic composition) are listed in Table 2.

[0063]

Table 2

[0064] In some embodiments, a kit for forming an etch resist mask according to some embodiments of the present invention can include the immobilized composition listed in Table 1 and the etch resist composition listed in Table 2.

[0065] Although specific features of the present invention have been described herein and in the drawings, many modifications, substitutions and changes of elements, and equivalents will readily occur to those skilled in the art. Accordingly, it should be understood that the appended claims are intended to cover all such modifications and changes that fall within the spirit of the present invention. The present invention provides, for example, the following: (Item 1) A method comprising: applying a first liquid composition containing a first reactive component onto a metal surface to form a primer layer; applying a second liquid composition containing a second reactive component onto the primer layer by image-like printing by a non-impact printing process to generate an etch resist mask according to a predetermined pattern; and when droplets of the second liquid composition contact the primer layer, the second reactive component chemically reacts with the first reactive component to immobilize the droplets. (Item 2) The method according to item 1, wherein the first reactive component is an immobilizing reactive component and the second reactive component is an etch resist reactive component. (Item 3) The method according to item 1, wherein the first reactive component is an etch resist reactive component and the second reactive component is an immobilizing reactive component. (Item 4) The method according to item 2 or 3, wherein the immobilizing reactive component and the etch resist reactive component are water-soluble, and the chemical reaction produces a two-component material insoluble in water and an acidic etch solution. (Item 5) The method according to item 1, removing a portion of the primer layer that did not participate in the chemical reaction; and performing an etching process using a metal etching solution to remove exposed metal portions not covered by the etch resist mask. (Item 6) The method according to item 5, A method characterized in that the step of removing the primer layer portion and the step of performing the etching process are carried out simultaneously. (Item 7) The method according to item 1, characterized in that the application of the first liquid composition is carried out imagewise by non-impact printing. (Item 8) The method according to item 1, wherein either one of the first reactive component and the second reactive component is an immobilized component, the immobilized component comprising at least one of polyethyleneimine, divalent metal salts, acids, heteropolymers of vinylpyrrolidone, dimethylaminopropylmethacrylamide, methacryloylaminopropyldodecyldimethylammonium chloride, polyquaternary amines, polyamines present in natural form or as ammonium salts, or any mixture thereof. (Item 9) The method according to item 1, characterized in that either one of the first reactive component and the second reactive component is an etch resist component comprising at least one of acrylate, styrene acrylate, phosphate, sulfonate and any mixture thereof. (Item 10) A two-component ink composition set for applying an etch resist mask on a metal layer, comprising a first liquid composition containing an immobilized reactive component and a second liquid composition containing an etch resist reactive component, characterized in that the immobilized reactive component and the etch resist reactive component can undergo a chemical reaction to form a two-component material insoluble in water and an acidic etch solution. (Item 11) The two-component ink composition set according to item 10, The two-component ink composition set, wherein the immobilized component contains at least one of polyethyleneimine, divalent metal salts, acids, heteropolymers of vinylpyrrolidone, dimethylaminopropylmethacrylamide, methacryloylaminopropyl lauryldimethylammonium chloride, polyquaternary amines, polyamines present in natural form or as ammonium salts, or any mixture thereof. (Item 12) The two-component ink composition set according to Item 10, The two-component ink composition set, wherein the etch resist component contains at least one of acrylates, styrene acrylates, phosphates, sulfonates, and any mixture thereof.

Claims

1. A method comprising: depositing a first composition comprising a first reactive component on a metal layer of a substrate; depositing a second composition comprising a second reactive component on a selected portion of the substrate, such that a chemical reaction between the first reactive component and the second reactive component forms a binary material mask in a pattern for protecting selected regions of the metal layer; depositing an etch solution to remove the metal layer in regions not protected by the binary material mask; and after depositing the etch solution, removing the binary material mask, wherein one of the first reactive component and the second reactive component comprises a cationic component and the other of the first reactive component and the second reactive component comprises an anionic component.

2. The method of claim 1, wherein the cationic component comprises one imine group, one amine group, or both, and the anionic component comprises one phosphate group, one sulfonate group, one acrylate group, or any combination thereof.

3. The method of claim 1, wherein the binary material mask is insoluble in at least one of water and the etch solution.

4. The method of claim 1, further comprising drying the first composition deposited on the metal layer before depositing the second composition.

5. The method of claim 1, further comprising removing one or more additional components that do not undergo the chemical reaction of the first composition deposited on the metal layer.

6. The method of claim 5, wherein the step of removing one or more additional components of the first composition and the step of depositing the etch solution are performed simultaneously.

7. The method according to any one of claims 1 to 6, wherein the first composition, the second composition, or both are deposited by inkjet printing.

8. The method according to any one of claims 1 to 6, wherein the metal layer comprises copper.

9. The method according to any one of claims 1 to 6, wherein the second composition further comprises a dye.

10. A method comprising: depositing a first composition comprising a cationic component on a metal layer of a substrate; ​ ​ ​ ​ ​ ​ ​ ​ ​ Depositing a second composition containing an anionic component on a selected portion of the substrate to form a two-component material mask in a pattern for protecting selected regions of the metal layer by a chemical reaction between the cationic component and the anionic component; Removing the metal layer in regions not protected by the two-component material mask; And After removing the metal layer, removing the two-component material mask. A method comprising. **Claim 11** The method according to claim 10, wherein the cationic component, the anionic component, or both are deposited by inkjet. **Claim 12** The method according to claim 10, further comprising drying the first composition deposited on the metal layer before depositing the second composition. **Claim 13** The cationic component includes one imine group, one amine group, or both. The anionic component includes one phosphate group, one sulfonate group, one acrylate group, or any combination thereof. The method according to any one of claims 10 to 12. **Claim 14** A method comprising: Depositing a first composition containing a first reactive component on a metal layer of a substrate; Depositing a second composition containing a second reactive component on a selected portion of the substrate to form a two-component material mask in a pattern for protecting selected regions of the metal layer by a chemical reaction between the first reactive component and the second reactive component; Removing the metal layer in regions not protected by the two-component material mask; After removing the metal layer, removing the two-component material mask, and wherein one of the first reactive component and the second reactive component includes a cationic component and the other of the first reactive component and the second reactive component includes an anionic component. A method. **Claim 15** The method according to claim 14, further comprising depositing the first composition, the second composition, or both by inkjet printing. **Claim 16** The method according to claim 14, further comprising drying the first composition deposited on the metal layer before depositing the second composition. **Claim 17** The method according to any one of claims 14 to 16, further comprising the step of removing a portion of the first reactive component that does not undergo a chemical reaction with the second reactive component.

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