Printed wiring board manufacturing method

Abstract

To provide a method for manufacturing a printed wiring board, a method for manufacturing a resin base material, and a method for forming a seed layer.SOLUTION: A method for manufacturing a printed wiring board includes the steps of: forming a projection containing a copper oxide on the surface of a copper foil; treating the surface of the copper foil where the projection is formed with a dissolving agent; plating the surface of the copper foil where the projection is formed using a plating liquid; stacking a copper foil on a resin base material so as to bring the surface of the copper foil where the projection is formed into contact therewith; applying dynamic energy to a part or all of the copper foil stacked on the resin base material without heating; obtaining a resin base material in which the copper foil to which the dynamic energy is applied is removed from the resin base material, a part or all of the projection is transferred, and a seed layer is formed; and subjecting the surface of the seed layer to copper plating treatment.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a printed wiring board. [Background technology]

[0002] Known circuit formation methods for printed wiring boards and semiconductor package substrates include subtractive methods and semi-additive methods such as SAP (Semi-Additive Process) and M-SAP (Modified Semi-Additive Process) (Patent Document 1).

[0003] In the subtractive method, a resist is formed on the necessary areas of a laminate consisting of copper foil laminated on a resin substrate, and the copper foil in the areas where there is no resist is etched and then removed to form copper wiring. In the SAP and MSAP methods, a resist is formed on the areas where wiring is not to be made on a resin substrate with a metal seed layer on its surface, and then a plating process is performed. After removing the resist, the remaining seed layer is etched to form fine circuits.

[0004] In the SAP method, a seed layer is formed on the surface of a resin substrate by electroless plating, while in the MSAP method, a resin substrate with copper foil is used as the seed layer. When manufacturing a resin substrate with copper foil, numerous fine protrusions are formed on the copper foil in advance, which is an effort to improve the adhesion between the copper foil and the resin substrate.

[0005] In contrast to these methods, a method has been disclosed in which copper foil having numerous fine protrusions is thermocompression bonded to a resin substrate, and then the copper foil is peeled off from the resin substrate to obtain a resin substrate to which numerous fine protrusions have been transferred; resist is formed on the surface of the resin substrate in areas where wiring will not be formed; plating is then performed; and the resist is removed to form a circuit (Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-034216 [Patent Document 2] International Publication No. 2021 / 079952 Brochure Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a novel method for manufacturing a printed wiring board. [Means for solving the problem]

[0008] One embodiment of the present invention is a method for transferring protrusions on a copper foil surface to a resin substrate to form a seed layer, the method comprising the steps of forming protrusions containing copper oxide on a copper foil surface, treating the copper foil surface on which the protrusions are formed with a solvent, plating the copper foil surface on which the protrusions are formed with a plating solution, laminating the copper foil to the resin substrate so that the copper foil surface on which the protrusions are formed is in contact with the resin substrate, and applying mechanical energy without heating to part or all of the copper foil laminated on the resin substrate. The plating step may be performed after the solvent treatment step. The solvent treatment step and the plating step may be performed simultaneously by adding the solvent to the plating solution. The mechanical energy may be pressure. The copper oxide-containing protrusions may be formed by oxidation treatment with an oxidizing agent. The oxidation treatment may be performed under conditions including a temperature of 40 to 95°C and a time of 0.5 to 30 minutes. The oxidizing agent may include sodium chlorite, sodium hypochlorite, potassium chlorate, or potassium perchlorate. The resin substrate may contain at least one insulating resin selected from the group consisting of polyphenylene ether (PPE), epoxy, polyphenylene oxide (PPO), polybenzoxazole (PBO), polytetrafluoroethylene (PTFE), liquid crystal polymer (LCP), thermoplastic polyimide (TPI), fluororesin, polyetherimide, polyetheretherketone, polycycloolefin, bismaleimide resin, low dielectric constant polyimide, and cyanate resin. The method may further include a step of removing the copper foil to which the mechanical energy has been applied from the resin substrate, so that part or all of the protrusions of the copper foil to which the mechanical energy has been applied are transferred, thereby obtaining the resin substrate on which a seed layer has been formed.

[0009] Another embodiment of the present invention is a method for producing a resin substrate having copper oxide, comprising the steps of: forming protrusions containing copper oxide on the copper foil surface; treating the copper foil surface on which the protrusions are formed with a solvent; plating the copper foil surface on which the protrusions are formed using a plating solution; laminating the copper foil on the resin substrate so that the copper foil surface on which the protrusions are formed is in contact with the resin substrate; applying mechanical energy without heating to part or all of the copper foil laminated on the resin substrate; and removing the copper foil to which the mechanical energy has been applied from the resin substrate, so that part or all of the protrusions on the part of the copper foil to which the mechanical energy has been applied are transferred, thereby obtaining the resin substrate on which a seed layer has been formed.

[0010] A further embodiment of the present invention is a method for manufacturing a printed wiring board, comprising the steps of: forming protrusions containing copper oxide on the copper foil surface; treating the copper foil surface on which the protrusions are formed with a solvent; plating the copper foil surface on which the protrusions are formed using a plating solution; laminating the copper foil on the resin substrate so that the copper foil surface on which the protrusions are formed is in contact with the resin substrate; applying mechanical energy without heating to part or all of the copper foil laminated on the resin substrate; removing the copper foil to which the mechanical energy has been applied from the resin substrate, so that part or all of the protrusions on the part of the copper foil to which the mechanical energy has been applied are transferred to obtain the resin substrate on which a seed layer has been formed; and performing a copper plating treatment on the surface of the seed layer. [Effects of the Invention]

[0011] The present invention provides a novel method for producing a printed wiring board. [Brief explanation of the drawings]

[0012] [Figure 1]This is a schematic diagram of a seed layer in one embodiment of the present invention. The gray portion represents the resin substrate, and the black portion represents the copper foil portion transferred to the resin substrate. When the copper foil is removed from the resin substrate, (A) an example of a case where the copper foil protrusion is transferred just on the surface of the resin substrate, and (B) an example of a case where the copper foil protrusion is transferred away from the surface of the resin substrate and inside the copper foil protrusion. The two straight lines correspond to the surface of the resin substrate after the copper foil is removed, and the position of a plane configured to include the bottom of the hole formed in the resin substrate by the copper foil protrusion, respectively. The portion sandwiched between these two straight lines is the seed layer, and the distance between the two straight lines represented by arrows is the thickness of the seed layer. [Figure 2A] In one example of the present invention, a copper foil was placed on an insulating resin film that had been heat-laminated onto a copper-clad substrate, with the shiny side of the copper foil in contact with the resin film. Then, a ballpoint pen (Fig. 1A1) or a magic marker (Fig. 1A2) was used to apply pressure to the copper foil. [Figure 2B] In one example of the present invention, photographs are shown showing the results of observing the laminated surfaces of copper foil and resin when pressure is applied to a portion of the copper foil laminated to resin by drawing a straight line with a ballpoint pen (FIG. 1B1) or a curved line with a magic marker (FIG. 1B2) on the copper foil, and then the copper foil is removed from the resin. [Figure 3A] FIG. 10 is a diagram showing the laminate surface with the copper foil before the resin to which the metal containing copper oxide has been transferred from the copper foil is placed in a dryer in one embodiment of the present invention. [Figure 3B] FIG. 10 is a diagram showing the laminated surface with the copper foil after the resin to which the metal containing copper oxide has been transferred from the copper foil is placed in a dryer in one embodiment of the present invention. [Figure 3C] FIG. 1 is a diagram showing the laminated surface of the resin to which the metal containing copper oxide has been transferred from the copper foil after electrolytic nickel plating has been performed in one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not necessarily limited thereto. The objects, features, advantages, and concepts of the present invention will be apparent to those skilled in the art from the description in this specification, and those skilled in the art will be able to easily reproduce the present invention from the description in this specification. The embodiments and specific examples of the invention described below show preferred embodiments of the present invention and are presented for illustrative or explanatory purposes, and are not intended to limit the present invention thereto. It will be apparent to those skilled in the art that various changes and modifications can be made based on the description in this specification within the spirit and scope of the present invention disclosed herein.

[0014] ==How to form a seed layer== The method disclosed in this specification is a method for transferring protrusions on a copper foil surface to a resin substrate and forming a seed layer, and includes the steps of forming protrusions containing copper oxide on the copper foil surface, treating the copper foil surface on which the protrusions have been formed with a solvent, plating the copper foil surface on which the protrusions have been formed with a plating solution, laminating the copper foil so that the copper foil surface on which the protrusions have been formed is in contact with the resin substrate, and applying mechanical energy without heating to part or all of the copper foil laminated on the resin substrate. Details of this method are described below.

[0015] (1) Preparing the copper foil The copper foil used in this method is preferably made of pure copper with a purity of 95% by mass or more, 99% by mass or more, or 99.9% by mass or more, more preferably made of tough pitch copper, deoxidized copper, or oxygen-free copper, and even more preferably made of oxygen-free copper with an oxygen content of 0.001% to 0.0005% by mass. There are no particular limitations on its thickness, but it is preferably 0.1 μm to 100 μm, more preferably 0.5 μm to 50 μm.

[0016] (2) Oxidation treatment process First, the copper foil surface is subjected to an oxidation treatment to form protrusions containing copper oxide on the copper foil surface, which roughens the copper material surface.

[0017] Before this oxidation treatment, a surface roughening treatment such as soft etching or etching may be performed. Furthermore, before the oxidation treatment, degreasing treatment, acid washing to remove natural oxide films and make the surface uniform, or alkali treatment to prevent acid from being carried over into the oxidation step after acid washing may be performed. The alkali treatment method is not particularly limited, but it is preferable to treat with a 0.1 to 10 g / L, more preferably a 1 to 2 g / L, aqueous alkali solution, such as a sodium hydroxide solution, at 30 to 50°C for about 0.5 to 2 minutes.

[0018] The oxidation treatment method is not particularly limited, and the protrusions may be formed by heat treatment or anodic oxidation, but it is preferable to form the protrusions using an oxidizing agent.

[0019] The oxidizing agent is not particularly limited, and examples thereof include aqueous solutions of sodium chlorite, sodium hypochlorite, potassium chlorate, and potassium perchlorate. Various additives (e.g., phosphates such as trisodium phosphate dodecahydrate) and surface-active molecules may be added to the oxidizing agent. Examples of surface-active molecules include porphyrin, porphyrin macrocycle, expanded porphyrin, ring-contracted porphyrin, linear porphyrin polymer, porphyrin sandwich coordination complex, porphyrin array, silane, tetraorgano-silane, aminoethyl-aminopropyltrimethoxysilane, (3-aminopropyl)trimethoxysilane, (1-[3-(trimethoxysilyl)propyl]urea), (3-aminopropyl)triethoxysilane, ((3-glycidyloxypropyl)trimethoxysilane), and (3-chloropropyl)trimethoate. Examples include oxysilane, (3-glycidyloxypropyl)trimethoxysilane, dimethyldichlorosilane, 3-(trimethoxysilyl)propyl methacrylate, ethyltriacetoxysilane, triethoxy(isobutyl)silane, triethoxy(octyl)silane, tris(2-methoxyethoxy)(vinyl)silane, chlorotrimethylsilane, methyltrichlorosilane, silicon tetrachloride, tetraethoxysilane, phenyltrimethoxysilane, chlorotriethoxysilane, ethylene-trimethoxysilane, amines, and sugars.

[0020] The oxidation reaction conditions are not particularly limited, but the liquid temperature of the oxidizing agent is preferably 40 to 95°C, more preferably 45 to 80°C. The reaction time is preferably 0.5 to 30 minutes, more preferably 1 to 10 minutes. The concentration of the oxidizing agent is not particularly limited, but is preferably 5 to 300 g / L, more preferably 10 to 250 g / L.

[0021] The surface of this copper oxide layer may be reduced with a reducing agent, in which case cuprous oxide may be formed on the surface of the copper oxide-containing layer. Examples of reducing agents used in this reduction step include dimethylamine borane (DMAB), diborane, sodium borohydride, and hydrazine.

[0022] Furthermore, a chelating agent, particularly a biodegradable chelating agent, may be used with the copper oxide layer to adjust the size, thickness, height, and length of the copper oxide-containing protrusions. The chelating agent is not particularly limited, but examples include ethylenediaminetetraacetic acid, diethanolglycine, tetrasodium L-glutamate diacetate, ethylenediamine-N,N'-disuccinic acid, sodium 3-hydroxy-2,2'-iminodisuccinate, trisodium methylglycine diacetate, tetrasodium aspartate diacetate, disodium N-(2-hydroxyethyl)iminodiacetate, sodium gluconate, and nickel chloride. The pH of the chelating agent solution is not particularly limited, but is preferably alkaline, more preferably between 8 and 10.5, even more preferably between 9.0 and 10.5, and even more preferably between 9.8 and 10.2.

[0023] The resistivity of pure copper is 1.7 x 10 -8 (Ωm), whereas copper oxide is 1 to 10 (Ωm) and cuprous oxide is 1×10 6 ~1×10 7 (Ωm), the layer containing copper oxide has low conductivity, and even if the amount of the layer containing copper oxide transferred to the resin substrate is large, transmission loss due to the skin effect is unlikely to occur when forming a circuit for a printed wiring board or a semiconductor package substrate using the copper foil according to the present invention.

[0024] (3) Dissolution process The copper foil surface on which the protrusions have been formed is subjected to a step of treating with a solvent to facilitate breaking off the surface layer portion including the protrusions from the copper foil. This step may be performed simultaneously with the plating step described below by adding the solvent to the plating solution.

[0025] The dissolving agent may contain a component that dissolves copper oxide, and may be selected from chlorides (nickel chloride, potassium chloride, zinc chloride, iron chloride, chromium chloride, tin(II) chloride, etc.), ammonium salts (ammonium citrate, ammonium chloride, ammonium sulfate, nickel ammonium sulfate, etc.), chelating agents (ethylenediaminetetraacetic acid, diethanolglycine, tetrasodium L-glutamate diacetate, ethylenediamine-N,N'-disuccinic acid, sodium 3-hydroxy-2,2'-iminodisuccinate, trisodium methylglycine diacetate, tetrasodium aspartate diacetate, disodium N-(2-hydroxyethyl)iminodiacetate, sodium gluconate, etc.), and citric acid.

[0026] For example, when treating with nickel chloride, it is preferable to immerse the copper foil on which the protrusions have been formed in a nickel chloride solution (concentration 45 g / L or higher) at room temperature or a temperature higher than room temperature for 5 seconds or more. Furthermore, when performing this treatment simultaneously with plating, it is preferable to add nickel chloride to the plating solution, immerse the foil in the plating solution for 5, 10, 15, 20, 30 seconds, 1 minute, or 2 minutes, and then perform plating. The immersion time may be changed as appropriate depending on the oxide film thickness.

[0027] (4) Plating process In this step, the copper foil surface on which the protrusions have been formed is plated using a plating solution. The plating method is not particularly limited, and plating can be performed by electrolytic plating, electroless plating, vacuum deposition, chemical conversion treatment, etc., but electrolytic plating is preferred because it is preferable to form a uniform plating layer.

[0028] In the case of electrolytic plating, nickel plating and nickel alloy plating are preferred. Examples of metals formed by nickel plating and nickel alloy plating include pure nickel, Ni-Cu alloy, Ni-Cr alloy, Ni-Co alloy, Ni-Zn alloy, Ni-Mn alloy, Ni-Pb alloy, and Ni-P alloy.

[0029] Examples of metal salts used for nickel plating include nickel sulfate, nickel sulfamate, nickel chloride, nickel bromide, zinc oxide, zinc chloride, diamminedichloropalladium, iron sulfate, iron chloride, chromic anhydride, chromium chloride, sodium chromium sulfate, copper sulfate, copper pyrophosphate, cobalt sulfate, and manganese sulfate.

[0030] In nickel plating, the plating solution preferably contains, for example, nickel sulfate (e.g., 100 g / L or more and 350 g / L or less), nickel sulfamate (e.g., 100 g / L or more and 600 g / L or less), nickel chloride (e.g., more than 0 g / L and 300 g / L or less), or a mixture thereof, but may also contain additives such as sodium citrate (e.g., more than 0 g / L and 100 g / L or less) or boric acid (e.g., more than 0 g / L and 60 g / L or less).

[0031] When electroplating is performed on the surface of copper foil that has been oxidized, the copper oxide on the surface is first reduced to cuprous oxide or pure copper, and an electric charge is used to reduce it, resulting in a time lag before plating begins. After that, the metal that forms the metal layer begins to deposit. The amount of electric charge varies depending on the type of plating solution and the amount of copper oxide. For example, when applying Ni plating to copper foil, the area of ​​the copper foil to be electroplated, dm 2 It is preferable to apply a charge of 10 C or more and 90 C or less, and more preferable to apply a charge of 20 C or more and 65 C or less per charge.

[0032] The current density is not particularly limited, but is preferably 0.2 A / dm 2 ~10A / dm 2The current may be changed depending on the time until the oxide contained in the protrusions on the surface of the copper foil is partially reduced and the time during which the plating is being coated.

[0033] The amount of metal deposited on the surface of the copper foil by plating is not particularly limited, but is preferably 0.8 to 6.0 mg / dm 2 The amount of metal attached can be calculated by, for example, dissolving the structure in an acidic solution, measuring the amount of metal by ICP analysis, and dividing the amount by the plan view area of ​​the structure.

[0034] (5) Laminating copper foil onto a resin substrate In this step, first, copper foil is laminated onto a resin substrate so that the copper foil surface including the protrusions is in contact with the resin substrate. When laminating, it is sufficient to simply place the copper foil on the resin substrate, and it is preferable not to bond it with heat, pressure, or the like.

[0035] The resin substrate used is not particularly limited, but preferably contains or is made of at least one insulating resin selected from the group consisting of polyphenylene ether (PPE), epoxy, polyphenylene oxide (PPO), polybenzoxazole (PBO), polytetrafluoroethylene (PTFE), liquid crystal polymer (LCP), thermoplastic polyimide (TPI), fluororesin, polyetherimide, polyetheretherketone, polycycloolefin, bismaleimide resin, low-dielectric-constant polyimide, and cyanate resin. The resin substrate may further contain inorganic filler or glass fiber. The relative dielectric constant of the resin substrate used is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.8 or less.

[0036] To transfer the metal on the surface of the copper foil to the resin substrate, mechanical energy is applied to part or all of the copper foil without heating. The mechanical energy may be pressure. The conditions for applying the mechanical energy (e.g., temperature, pressure, time, etc.) are preferably, for example, a temperature of 0°C to 40°C and a pressure of 0 to 20 MPa for 0.1 seconds to 5 hours.

[0037] The surface profile of the copper foil, including the protrusions, is transferred to the resin substrate at the portion where mechanical energy is applied. Therefore, holes complementary to the protrusions on the copper foil surface are formed on the surface of the resin substrate. The average depth of the holes is not particularly limited, but may be 2.50 μm or less, more preferably 2.00 μm or less, and even more preferably 1.70 μm or less. It is also preferably 0.01 μm or more, more preferably 0.10 μm or more, and even more preferably 0.36 μm or more. If the depth is less than 0.01 μm, adhesion to the resin substrate decreases. If it exceeds 2.50 μm, wiring formability deteriorates. The average depth of the holes can be measured, for example, using SEM images.

[0038] (6) Removing the copper foil In this process, by removing the copper foil from the resin substrate on which it is laminated, some or all of the protrusions present in the area where mechanical energy was applied are peeled off from the copper foil and transferred to the resin substrate, resulting in a resin substrate with a seed layer formed. In this specification, the term "seed layer" refers to the layer formed between the surface of the resin substrate after the copper foil has been removed and a surface configured to include the bottom of the holes formed in the resin substrate by the copper foil protrusions (Figure 1). Therefore, the holes and the metal derived from the copper foil transferred to the holes are contained within this layer. The bottom of the holes refers to the bottom of the multiple holes that is farthest from the peeled copper foil surface, and the surface configured to include the bottom of the holes is parallel to the surface of the resin substrate after the copper foil has been removed.

[0039] The method for removing the copper foil from the resin substrate is not particularly limited, but the copper foil may be removed manually using a tool such as tweezers.

[0040] It is preferable that the metal contained in the protrusions present in the portion to which mechanical energy is applied is transferred to the resin substrate in such a manner that 70% or more, 80% or more, 90% or more, 95% or more, 99% or more, or 99.9% or more of the protrusions are transferred.On the other hand, it is preferable that the protrusions present in the portion to which mechanical energy is not applied are transferred to the resin substrate in a proportion of 30% or less, 20% or less, 10% or less, 5% or less, 1% or less, or 0.1% or less of the resin substrate.

[0041] (7) Plating process In this process, the surface of the resin substrate on which the seed layer has been formed is plated. At this time, the metal derived from the copper foil exposed on the surface of the resin substrate is plated, but the resin substrate itself is not plated, so that the plated metal can be used as wiring for the printed wiring board.

[0042] The plating method is not particularly limited, and may be electrolytic plating or electroless plating. The metal is also not particularly limited, and for example, one metal selected from Ni, Sn, Al, Cr, Co, and Cu may be used, but it is preferable to use copper and plate it by electroless plating. The plating thickness is not particularly limited, and may be about 0.02 to 2 μm.

[0043] (8) Manufacturing method for printed wiring boards First, a copper foil is prepared that has been surface-treated according to the above (1) to (4).

[0044] Next, a laminate of the resin substrate and the copper foil is produced according to steps (5) and (6). In step (5), mechanical energy is applied to the copper foil in the same shape as the desired copper wiring circuit. This causes a metal containing copper oxide to be transferred from the copper foil to the resin substrate in the same shape as the desired copper wiring circuit. After step (6), if necessary, the metal from the copper foil that has been transferred to areas other than the circuit shape on the surface of the resin substrate may be removed by etching.

[0045] Finally, by plating the resin substrate according to (7), copper wiring can be formed on the seed layer formed on the resin substrate.

[0046] By manufacturing a printed wiring board in this manner, an etching step using a resist, which is required in the conventional subtractive method, SAP method, MSAP method, etc., is not necessary. [Example]

[0047] (1) Copper foil processing and protrusion transfer The shiny side (the glossy side, which is flat compared to the opposite side) of copper foil (DR-WS, thickness: 18 μm) manufactured by Furukawa Electric Co., Ltd. was used as the copper material, and the following treatment was carried out.

[0048] (1-1) Pretreatment The copper foil was degreased by immersing it in a 5 g / L aqueous solution of potassium hydroxide at a liquid temperature of 25° C. for 1 minute to remove dirt from the copper surface, and then washed with water.

[0049] (1-2) Oxidation treatment After the pretreatment, the shiny side of the copper foil was immersed in an oxidizing agent (sodium chlorite 58.3 g / L; potassium hydroxide 20 g / L) at a temperature of 73°C for 2 minutes to perform an oxidation treatment, forming fine protrusions on the surface of the copper foil.

[0050] (1-3) Electrolytic plating The copper foil that had undergone oxidation treatment was immersed for 30 seconds in a Ni electroplating solution (nickel sulfate 240 g / L; trisodium citrate 20 g / L) containing a dissolving agent (nickel chloride 45 g / L), and then immersed at 45°C with a current density of 0.5 A / dm 2 , 64 seconds (i.e., 32C / dm 2 Electrolytic plating was carried out under the conditions of (copper foil area).

[0051] (1-4) Transfer process Copper foil was placed on top of an insulating resin film (product name: ADFLEMA®, manufactured by Namics Corporation) that had been heat-laminated onto a copper-clad substrate, so that the shiny side of the copper foil was in contact with the resin film (Figure 2A). At room temperature, partial pressure was applied to the copper foil by drawing with a ballpoint pen (Figure 2A1) or a magic marker (Figure 2A2). Straight lines were drawn with the ballpoint pen (Figure 2B1), and curved lines were drawn with the magic marker (Figure 2B2). The copper foil laminated to the resin was then removed, and the copper foil / resin laminate surface was observed. The observation results are shown in Figure 1B. The laminate surface refers to the surface where the copper foil and resin come into contact when the copper foil and resin are laminated.

[0052] (1-5)Result As shown in Figure 2B, the straight lines appear white on the copper foil surface (Figure 2B1, top), and black on the resin surface (Figure 2B1, bottom). Also, the curved lines appear white on the copper foil surface (Figure 2B2, right), and black on the resin surface (Figure 2B2, left). Thus, only the metal, including copper oxide, in the area on the copper foil surface where pressure was applied using the ballpoint pen or marker was transferred to the resin.

[0053] (2) Plating (2-1) Method

[0054] The resin with the seed layer formed was placed in a dryer and heated at 170°C for 30 minutes to harden the resin film. Figure 2 shows the surface appearance before drying (Figure 3A) and after drying (Figure 3B).

[0055] Next, acid-washed copper foil (DR-WS, thickness: 18 μm) was attached to a copper-clad substrate, and a cured resin film was attached to it with copper tape. This was then electrolytically plated with nickel using a plating solution (nickel sulfate 240 g / L, nickel chloride 45 g / L, trisodium citrate 20 g / L) at 45°C and a current of 0.40 A for 291 seconds.

[0056] (2-2) Results As shown in Figure 3C, the straight line (Figure 3C1) or curve (Figure 3C2) on which metal containing copper oxide was transferred from copper foil was nickel-plated overall, but the ends of the line where current flows easily (areas surrounded by ellipses in the figure) were particularly shiny and thickly plated with nickel.

Claims

1. A method for transferring protrusions on a copper foil surface to a resin substrate to form a seed layer, comprising: forming protrusions containing copper oxide on the surface of the copper foil; a step of treating the copper foil surface on which the protrusions are formed with a solvent; a step of plating the copper foil surface on which the protrusions are formed using a plating solution; laminating the copper foil on the resin base material so that the copper foil surface on which the protrusions are formed is in contact with the resin base material; a step of applying mechanical energy to a part or all of the copper foil laminated on the resin substrate without heating; Including, The condition for providing mechanical energy is to apply a pressure of more than 0 MPa and not more than 20 MPa at a temperature of 0°C to 40°C for 0.1 seconds to 5 hours.

2. 2. The method of claim 1, wherein the step of treating with the dissolving agent is followed by a step of plating.

3. 2. The method according to claim 1, wherein the step of treating with the dissolving agent and the step of plating are carried out simultaneously by adding the dissolving agent to the plating solution.

4. The method according to any one of claims 1 to 3, wherein the mechanical energy is pressure.

5. The method according to any one of claims 1 to 4, wherein the protrusions containing copper oxide are formed by oxidation treatment with an oxidizing agent.

6. 6. The method of claim 5, wherein the oxidation treatment is carried out under conditions comprising a temperature of 40 to 95°C and a time of 0.5 to 30 minutes.

7. 7. The method of claim 5 or 6, wherein the oxidizing agent comprises sodium chlorite, sodium hypochlorite, potassium chlorate, or potassium perchlorate.

8. The method according to any one of claims 1 to 7, wherein the resin substrate contains at least one insulating resin selected from the group consisting of polyphenylene ether (PPE), epoxy, polyphenylene oxide (PPO), polybenzoxazole (PBO), polytetrafluoroethylene (PTFE), liquid crystal polymer (LCP), thermoplastic polyimide (TPI), fluororesin, polyetherimide, polyetheretherketone, polycycloolefin, bismaleimide resin, low dielectric constant polyimide, and cyanate resin.

9. The method according to any one of claims 1 to 6, further comprising the step of removing the copper foil to which the mechanical energy has been applied from the resin substrate, and obtaining the resin substrate on which a seed layer has been formed by transferring part or all of the protrusions of the copper foil to which the mechanical energy has been applied.

10. A method for producing a resin substrate containing copper oxide, comprising: forming protrusions containing copper oxide on the surface of the copper foil; a step of treating the copper foil surface on which the protrusions are formed with a solvent; a step of plating the copper foil surface on which the protrusions are formed using a plating solution; laminating the copper foil on the resin base material so that the copper foil surface on which the protrusions are formed is in contact with the resin base material; a step of applying mechanical energy to a part or all of the copper foil laminated on the resin substrate without heating; removing the copper foil to which the mechanical energy has been applied from the resin base material, and obtaining the resin base material on which a seed layer has been formed by transferring part or all of the protrusions of the copper foil to which the mechanical energy has been applied; Including, The conditions for applying mechanical energy include applying a pressure of more than 0 MPa and not more than 20 MPa at a temperature of 0°C to 40°C for 0.1 seconds to 5 hours.

11. A method for manufacturing a printed wiring board, forming protrusions containing copper oxide on the surface of the copper foil; a step of treating the copper foil surface on which the protrusions are formed with a solvent; a step of plating the copper foil surface on which the protrusions are formed using a plating solution; laminating the copper foil on a resin substrate so that the copper foil surface on which the protrusions are formed is in contact with the resin substrate; a step of applying mechanical energy to a part or all of the copper foil laminated on the resin substrate without heating; removing the copper foil to which the mechanical energy has been applied from the resin base material, and obtaining the resin base material on which a seed layer has been formed by transferring part or all of the protrusions of the copper foil to which the mechanical energy has been applied; a step of performing copper plating on the surface of the seed layer; Including, The conditions for applying mechanical energy include applying a pressure of more than 0 MPa and not more than 20 MPa at a temperature of 0°C to 40°C for 0.1 seconds to 5 hours.

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