Method for manufacturing ultra-thin copper foil structure laminated with insulating sheet, and method for forming multilayer structure

Abstract

The present invention relates to a method for manufacturing an ultra-thin copper foil structure whereby high reliability can be achieved during production and assembly. The present invention basically provides a method for manufacturing an ultra-thin copper foil structure, wherein copper foil layers deposited by physical vapor deposition form a copper foil on a carrier film having a release layer, patterns are formed by etching, and then an insulating layer is formed on the release layer and the copper foil patterns to integrally form a support and a bonding structure.

Description

Method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet and a method for forming a multilayer structure

[0001] The present invention relates to a technology for manufacturing ultra-thin copper foil, and more specifically, to a method for manufacturing an ultra-thin copper foil structure capable of having high reliability during the production and assembly process.

[0002] Conventional printed circuit boards are generally manufactured by bonding a copper foil and an insulating substrate to form a copper-clad laminate, and then forming a conductor pattern on the copper foil surface through etching.

[0003] Recently, as the demand for miniaturization and high performance of electronic devices has increased and there has been significant progress in high-density mounting of components and high-frequency signals, there are high expectations for the quality of printed circuit boards, such as the miniaturization of conductor patterns (fine pitch) and high-frequency response. In response to this fine pitch, thin copper foils with a thickness of 9㎛ or less, and even 5㎛ or less, are currently required. However, such copper foils have low mechanical strength, which causes problems such as cracking or wrinkling during the manufacturing of printed circuit boards. To address this, carrier-attached copper foils have emerged as a technology that utilizes a thick metal foil as a carrier and electrodeposits an ultra-thin copper layer onto it with a release layer interposed therein.

[0004] In the case of the carrier-attached copper foil above, the surface of the ultra-thin copper layer is laminated to an insulating substrate and heat-pressed, after which the carrier is peeled off and removed through a release layer. After forming a circuit pattern with a resist on the exposed ultra-thin copper layer, a microcircuit is formed by etching the ultra-thin copper layer with a sulfuric acid-hydrogen peroxide-based etchant (MSAP: Modified-Semi-Additive-Process).

[0005] In the case of conventional carrier-attached ultra-thin copper foil, a method was applied in which a release layer is formed on a carrier copper foil having a predetermined thickness, a predetermined thickness is formed by sputtering a predetermined metal and copper, and the remaining thickness is formed through electroplating.

[0006] Korean Registered Patent Publication No. 10-1544161 discloses a conventional method for manufacturing ultra-thin copper foil, and FIG. 1 is a flowchart showing such a process.

[0007] Looking specifically at the prior art described above, it includes a step of forming a base film (S10), a step of forming a carrier film (S20), and a step of forming a copper plating layer (S30). In the step of forming the base film (S10), a sputtering process using copper is performed on the surface of a flexible insulating film having a PI material or a PET material to form a conductive layer composed of a copper sputtering layer. The step of forming the carrier film (S20) includes a step of performing a sputtering process using a nickel-chromium alloy on the surface of the base film to form a peeling layer having a uniform surface composed of a nickel-chromium alloy sputtering layer.

[0008] The step (S30) of forming the copper plating layer is to form a thin copper foil on the peeling layer of the carrier film by performing an electroplating process in which the carrier film is immersed in a copper plating solution containing copper sulfate, sulfuric acid, and a brightener, and then passed through a roll-to-roll process with a constant speed while gradually adjusting the current density of the voltage applied to the carrier film.

[0009] Because the steps for applying this copper foil manufacturing process to mass production are complex, productivity is only about 5 to 6 m / min. This leads to increased production costs and causes the problem of raising production unit costs.

[0010] Furthermore, due to the numerous process variables—such as concentration, pH, temperature, and voltage—in the roll-to-roll plating process, there is a high likelihood of defects, such as thickness variations, occurring particularly when forming ultra-thin copper foils with very thin thicknesses. This problem is exacerbated, especially in the case of ultra-thin copper foils in the 0.x µm range. Therefore, it is necessary to develop a highly reliable and economical technology to form ultra-thin copper foils.

[0011] The present invention was devised to solve the above problems and aims to provide an ultra-thin copper foil structure and a method for manufacturing the same, which has an improved production speed compared to conventional methods when manufacturing ultra-thin copper foil, while also having advantages in storage and transportation compared to conventional technology.

[0012] In addition, the present invention aims to provide a method for reliably forming a multilayer substrate using an ultra-thin copper foil structure.

[0013] To solve the above-mentioned problem, the present invention provides a method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet, comprising: a) a peeling layer coating step of forming a peeling layer (200) on a carrier film (300); b) a peeling layer surface treatment step of forming fine irregularities (210) by plasma treatment on the surface of the peeling layer; c) a physical vapor deposition step of forming a copper foil (100) by repeating the process of forming a copper foil layer (111) on the peeling layer by a physical vapor deposition process at a selected speed and number of times; d) an etching step of etching the copper foil by coating a photoresist and forming a copper foil pattern (110); e) an insulating layer coating step of forming an insulating layer (410) that supports the copper foil pattern by filling a space where the copper foil pattern is formed with resin; and f) a release film coating step of attaching a release film (420) on the insulating layer.

[0014] In addition, a method for forming a multilayer structure is provided, comprising the steps of: g) removing a carrier film including a release film and a release layer of a first thin copper foil structure and laminating a first insulating layer so that a first copper foil pattern corresponds to a core disposed on the lower side; h) removing a carrier film including a release film and a release layer of a second thin copper foil structure and laminating a second insulating layer on the first insulating layer so that a second copper foil pattern corresponds to a first copper foil pattern on the lower side and a core on the upper side; and i) pressing the laminated lower core, the first insulating layer and the first copper foil pattern, the second insulating layer and the second copper foil pattern, and the upper core, and fixing the multilayer structure by the bonding force of the insulating layers.

[0015] By the configuration of the present invention described above, the problem of high difficulty in the maintenance, transfer, and bonding processes of recent ultra-thin copper foil patterns is overcome, and since the copper foil pattern can be fixed and maintained in its manufactured state through an insulating layer, the reliability of not only copper foil manufacturing but also logistics and circuit manufacturing processes is improved.

[0016] In addition, since the insulating layer allows for strengthening adhesion while maintaining the overall structure's rigidity when forming a multilayer structure, it is possible to produce results that satisfy electrical and physical design conditions and reduce the defect rate, thereby contributing to productivity and economic efficiency.

[0017] Figure 1 is a flowchart of a conventional method for manufacturing ultra-thin copper foil.

[0018] FIG. 2 is a cross-sectional view illustrating the concept of a carrier film-type ultra-thin copper foil forming a composite irregularity of the present invention.

[0019] FIG. 3 is a diagram illustrating the process of forming an ultra-thin copper foil structure manufactured by the method of manufacturing an ultra-thin copper foil structure laminated with an insulating sheet of the present invention.

[0020] FIG. 4 is a diagram conceptually explaining the roll-to-roll process of each film in the method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet of the present invention.

[0021] FIG. 5 is a side cross-sectional view showing that an ultra-thin copper foil structure manufactured according to the present invention is bonded to a core to form a multilayer structure.

[0022] Hereinafter, a method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet according to a preferred embodiment of the present invention and a method for forming a multilayer structure will be described in detail with reference to the attached drawings.

[0023] The following embodiments combine the components and features of the present invention in a specific form. Each component or feature may be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, embodiments of the present invention may be constructed by combining some components and / or features. The order of operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

[0024] In the description of the drawings, parts, devices, and / or configurations that could obscure the essence of the invention have not been described, nor have parts, devices, and / or configurations that are understandable to those skilled in the art been described. Furthermore, parts referred to by the same reference numerals in the drawings refer to the same components or steps in a device configuration or method.

[0025] Throughout the specification, when a part is described as "comprising" or "including" a component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "...part" or "...unit" as used in the specification refer to a unit that performs at least one function or operation. Additionally, "one (a or an)," "one," "the," and similar related terms may be used in the context describing the invention (particularly in the context of the following claims) to include both singular and plural forms, unless otherwise indicated in the specification or clearly contradicted by the context.

[0026] The present invention basically provides a method for manufacturing an ultra-thin copper foil structure in which copper foil layers formed by applying a physical vapor deposition method on a carrier film having a release layer formed thereon form a copper foil, and after forming a pattern through etching, an insulating layer is formed on the release layer and the copper foil pattern to integrally form a support and adhesive structure.

[0027] In the present invention, predetermined copper foil layers are stacked together through a deposition process to form a single copper foil, and then a structure is formed through etching and insulating coating processes. Preferably, a physical vapor deposition (PVD) process may be applied. As long as such a physical vapor deposition process can vaporize copper and a different metal together and deposit them on a carrier film, the method and equipment thereof do not limit the present invention.

[0028] FIG. 2 is a flowchart for explaining a method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet of the present invention.

[0029]

[0030] a) Delamination layer coating step (S100)

[0031] This is a process of coating a release layer (200) on a carrier film (300).

[0032] The above carrier film (300) is a component that serves as a temporary support for a copper foil structure, allowing for stable deposition of the copper foil layer, easy subsequent removal, and easy storage and transportation.

[0033] According to an embodiment of the present invention, the carrier film (300) is made of a polymer material, and the carrier film (300) as a deposition or bonding substrate may be a flexible polymer film. For example, the polymer material may include one or more selected from PP (Polypropylene), PE (Polyethylene), PI (Polyimide), PET (Polyethyleneterephthalate), HDPE (High-Density Polyethylene), LCP (Liquid Crystal Polymer), Teflon, PC (Polycarbonate), PAR (Polyarylate), PES (Polyethersulfone), PEN (Polyethylenenaphthalate), FPR (Glass Fiber Reinforced Plastic), or aluminum foil.

[0034] The above carrier film (300) functions as a support for the overall structure, and a release layer (200) is formed on its upper surface. This release layer (200) may be made of a material that allows the separation of the copper foil to be achieved as intended. For example, silicon-based, fluorine-based, acrylic-based materials, etc., may be applied.

[0035] In the description of the present invention, the vertical direction may be selected according to the arrangement of rolls or films in the manufacturing process, and in the following description, the description is based on the state in which the carrier film (300) supports the structure from the bottom side to the top side.

[0036] For coating the above-mentioned peeling layer (200), slot die coating, which uniformly applies the peeling layer in a roll-to-roll manner, or spray coating, which is required for coating with a precise thickness, may be applied.

[0037]

[0038] b) Surface treatment step of the peeling layer (S200)

[0039] To improve bonding with the copper foil, it is desirable to form a fine irregular structure on the surface of the peeling layer (200). Since the surface area increases during copper foil deposition, adhesion is improved. For example, the fine irregular structure is formed by plasma treatment or a scratch scraping method. The thickness of the peeling layer (200) with the irregularities formed can be 0.3㎛ or more and 0.5㎛ or less.

[0040] The above plasma treatment forms plasma by introducing argon or oxygen in a vacuum, and the plasma collides with the surface of the peeling layer (200) to form micro roughness.

[0041] Scratch treatment is a process of forming fine scratches by applying abrasive devices such as sandpaper, brushes, or CNCs, and it is desirable to apply friction using a consistent pattern while considering the uniformity of surface roughness.

[0042] As a result of the above, the surface of the peeling layer (200) appears as a matte surface because light reflection is suppressed.

[0043] Meanwhile, a heat treatment process for stabilization may be additionally performed after the formation of the peeling layer (200) and the uneven structure. In one embodiment, the heat treatment may be performed at a temperature of 150°C or higher and 250°C or lower in a roll-to-roll method.

[0044]

[0045] c) Physical vapor deposition (PVD, S300)

[0046] Physical Vapor Deposition (PVD) is performed on copper or an alloy of copper and other metals by controlling a known source. Copper vaporized by the source is vaporized and adheres to the peeling layer (200).

[0047] The vacuum level inside the chamber for the above physical vapor deposition process (S100) is 10 -5 torr and 10 -8 It can be formed in a range greater than torr, and a high-speed roll-to-roll method can be applied.

[0048] A predetermined number of copper foil layers form a deposition unit, and the copper foil layers can be selected to have a thickness of 0.1 μm or more and 0.3 μm or less depending on the vapor deposition intensity and time.

[0049] The above deposition process can be repeated, and a copper foil with a final thickness of 0.4 μm can be formed.

[0050] For example, if the copper foil layer is 0.1㎛, four deposition steps are required, and if it is 0.2㎛, two deposition steps can be performed using a roll-to-roll method. However, in the case of two deposition steps, the density and strength were relatively weaker compared to four. The strength of the copper foil can be controlled by the above number of deposition steps and speed.

[0051] The above number of repetitions (n) is repeated until a set number of repetitions (ns) is reached, and to this end, a number determination step (S320) may be added.

[0052] The first deposited copper foil layer has a relatively high bonding ability to the fine irregularities of the peeling layer (200), and when the number of repetitions of the copper foil layer is completed, a copper foil is formed on the carrier film side.

[0053] d) Etching step (S400)

[0054] An etching technique may be applied to form a predetermined pattern on the copper foil. This can be viewed as a process of implementing a high-precision circuit design by forming a desired pattern on the copper foil layer.

[0055] Specifically, a photoresist (PR) can be coated on the copper foil, and spin coating or roll-to-roll coating may be applied in the coating. Then, the process may proceed through exposure using a photomask and UV, developing, etching, photoresist removal, and pattern verification. However, it is not limited to the above examples, and known etching techniques may be applied.

[0056] At this time, the L / S (Line / Space) size can be adjusted to 2㎛ or more and 100㎛ or less, which can contribute to miniaturization and integration.

[0057] The copper foil pattern formed in this way enables the implementation of precise two-dimensional or three-dimensional circuits in the core attachment process, and related embodiments will be described later.

[0058]

[0059] e) Insulation layer coating step (S510)

[0060] According to the concept of the present invention, the process involves forming an insulating layer immediately before the operation of rewinding to a predetermined roll after the copper foil pattern has been formed. When an insulating layer having electrical insulation and physical stability is formed on the copper foil layer on which patterning and etching have been completed as described above, structural reliability is provided.

[0061] The insulating layer may be made of resin, and preferably may be formed from an epoxy or silicone composite. Referring to FIG. 3, the height of the insulating layer (410) varies depending on the area because the copper foil pattern (110) is etched and formed in a selected structure on the peeling layer (200). To properly form this, slot die coating or spray coating may be applied during the roll-to-roll process.

[0062] The above insulating layer can be formed to a thickness of 0.5㎛ or more and 10㎛ or less, and since it can have different thicknesses depending on the area, it overlaps with the copper foil pattern in some sections.

[0063] Additionally, after forming the insulating layer, the resin can be cured through heat treatment and stably bonded with the copper foil pattern. The curing temperature can be 150°C or higher and 250°C or lower.

[0064] Due to the formation of the above insulating layer, precise thickness control is possible, and the application of a roll-to-roll method is possible, which not only provides high productivity but also allows for the expectation of physical stable performance such as flexibility, durability, moisture resistance, and heat resistance by using a silicone composite material.

[0065] Meanwhile, the above resin is cured by a heating process, and in this case, there is a concern that structural flexibility may be somewhat reduced when combined with a core to form a structure as described later. Considering this, an additional concept of the present invention proposes adding a polymer nanofiller to the insulating layer (410) to enhance flexibility and thermal stability. The polymer nanofiller may be selected, for example, silica (SiO₂) nanoparticles or a graphene-based filler. Accordingly, structural stability is maintained even in high-temperature environments, making it adaptable to various fields and highly useful for manufacturing flexible substrates (FPCB), in particular.

[0066] As another additional concept, the resin insulating layer (410) may further contain a self-healing functional material. For example, by including a healing agent in the form of microcapsules, cracks that occur in the resin during curing or aging due to use can be self-filled, thereby preventing contamination and maintaining electrical and physical stability for a considerable period. As an example, a polymer healing network that includes a dicyclopentadiene (DCPD)-based healing agent in the form of microcapsules and dynamic covalent bonds such as disulfide bonds within the resin matrix to restore cracks through chemical reactions can be considered.

[0067]

[0068] f) Release film coating step (S520)

[0069] A release film is formed on the above insulating layer to protect the structure.

[0070] The above release film may be made of high-strength materials such as PET, PI, PE, and HDPE, and may be treated with a silicone coating or a fluorine-based coating to impart peeling properties to the surface.

[0071] According to one embodiment, lamination can be performed on an insulating layer in a roll-to-roll manner, and pressure and heat can be controlled so that the release film adheres uniformly to the insulating layer.

[0072] FIG. 3 is a diagram illustrating the process of forming an ultra-thin copper foil structure manufactured by the method of manufacturing an ultra-thin copper foil structure laminated with an insulating sheet of the present invention.

[0073] FIG. 3(a) shows that a release layer (200) is formed on a carrier film (300) and a copper foil (100) is formed thereon. The above orientation may be changed depending on the manufacturing process or application process.

[0074] As previously stated, a peeling layer surface treatment (S200) for forming fine irregularities (210) to enhance copper foil bonding can be performed before a physical vapor deposition (S310) process is applied to the peeling layer (200).

[0075] In the illustrated embodiment, physical vapor deposition (S310) is performed four times, and copper foil layers (111) are sequentially stacked to form a single ultra-thin copper foil.

[0076] FIG. 3(b) shows that a copper foil pattern (110) is formed through etching (S400) after the copper foil (100) is formed. The L / S of the copper foil pattern (110) can be adjusted according to the pattern thickness of the photomask film.

[0077] In this state where the copper foil pattern (110) is etched, when viewed from the upper side, the area where the copper foil (100) is exposed and the area where the peeling layer (200) is exposed in the space between them are distinguished. An insulating layer (410) is formed to fill all of the above areas to ensure structural stability.

[0078] Figure 3(c) shows that the insulating layer (410) is filled into the space where the copper foil pattern (110) is formed, so that the copper foil pattern (110) and the insulating layer (410) form a single layer.

[0079] The insulating layer (410) fills all of the above spaces, thus providing electrical insulation and structural stability.

[0080] A release film (420) is coated on the upper side of the insulating layer (410), and the release film (420), the release layer (200), and the carrier film (300) are removed during circuit formation and function to stably support the structure of the copper foil pattern (110) and the insulating layer (410) only during the roll formation, storage, transfer, and bonding processes.

[0081] FIG. 4 is a diagram conceptually explaining the roll-to-roll process of each film in the method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet of the present invention.

[0082] The carrier copper foil film roll (101) is shown in a state where it is wound onto a predetermined roll after the coating of a predetermined peeling layer (200) (S100), the deposition of the copper foil (100) (S310), and the etching of the copper foil pattern (110) (S400) are completed.

[0083] The insulating layer (410) is positioned above it and can be drawn out from the insulating roll (411) and bonded onto the carrier copper foil film roll (101).

[0084] The release layer roll (421) can draw out the release film (420) and laminate it onto the insulating layer (410).

[0085] When the Roll-to-Roll process is completed by a predetermined temperature and pressure and the ultra-thin copper foil structure (1000) is formed, it can be slit to prepare for core attachment. The slitting can be performed by a known slitting device (500) and can be formed with a width selected according to the circuit, such as a PCB.

[0086] FIG. 5 is a side cross-sectional view showing that an ultra-thin copper foil structure manufactured according to the present invention is bonded to a core to form a multilayer structure.

[0087] Let's examine the process of forming a multilayer structure from the lower core (600).

[0088] The above core (600) may be a component or device capable of withstanding heat and pressure, supporting the entire layer as a basic structure of an electrical structure, and may be, for example, CCL (Copper Clad Laminate) or a substrate base, but the type is not limited.

[0089]

[0090] g) Bonding step of the first electrode foil structure

[0091] g-1) Removal of release film and carrier film

[0092] This is a process of removing the release layer (200) together with the carrier film (300) from the first electrode foil structure and preparing to attach it to the lower core (600).

[0093] Through the above process, the first copper foil pattern (110a) wrapped with the first insulating layer (410a) is exposed.

[0094] g-2) Combination of copper foil pattern and lower core

[0095] The layers of the exposed first copper foil pattern (110a) and the first insulating layer (410a) are laminated at selected locations on the core.

[0096]

[0097] h) Bonding step of the second electrode foil structure

[0098] h-1) Removal of release film and carrier film

[0099] This is a process of preparing to remove the release layer (200) together with the carrier film (300) from the second electrode copper foil structure and to attach it to the core (600), and through this process, the second copper foil pattern (110b) wrapped with the second insulating layer (410b) is exposed.

[0100] h-2) Combination of copper foil pattern and lower core

[0101] In the layer of the exposed second copper foil pattern (110b) and the second insulating layer (410b), the lower side where the second copper foil pattern (110b) is exposed is attached to the first insulating layer (410a), and the upper side is attached to the upper core (600).

[0102]

[0103] i) Fixing of multi-layer structures

[0104] After lamination is completed as described above, the core, the first copper foil, the second copper foil, and the core are combined through a press process using known heat and pressure. The overall structure is firmly maintained by the combination of insulating layers (410). Specifically, the lower core (600) and the lower side of the first insulating layer (410a) are combined, the first insulating layer (410a) and the second insulating layer (41b) are combined, and the second insulating layer (41b) and the upper core (600) are combined. It should be noted that since the combination can be achieved by a simple compression method using a resin that is pre-formed as described above, the reliability of the circuit board configuration is high, and there is an advantage of a simple process. Meanwhile, during the bonding process between the substrate and the copper foil pattern, since the micro-irregularities of the copper foil pattern are formed in the area combined with the micro-irregularities of the release layer, close electrical contact is possible during the pressurization and deformation process.

[0105] Meanwhile, in the above press process, ultrasonic vibration can be applied from the side to ensure the bonding between the upper and lower insulating layers (410a, 410b) and the uniformity of crack filling and distribution. That is, by applying pressure to the upper and lower sides to laminate the four sheets, ultrasonic vibration can be introduced from the side to allow the resin components to tightly bond the elements. Through this process, the high-temperature environment can be minimized, thereby preventing thermal damage to the material, especially the resin.

[0106] The above-described multilayer structure is not limited to the above examples and can be formed in various ways depending on the type of copper foil (100) and insulating layer (410) and the number of layers, etc.

[0107] By the method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet and the method for forming a multilayer structure according to the present invention as described above, the problem of high difficulty in the maintenance, transportation, and bonding processes of recent ultra-thin copper foil patterns is overcome, and since the copper foil pattern can be fixed and maintained in its manufactured state through an insulating layer, the reliability of the copper foil manufacturing, as well as logistics and circuit manufacturing processes, is improved.

[0108] In addition, since the insulation layer allows for strengthening adhesion while maintaining the overall structure's rigidity when forming a multilayer structure, it is possible to produce results that actually satisfy electrical and physical design conditions and contribute to productivity and economic efficiency by reducing the defect rate.

[0109] In the foregoing, the present invention has been described in detail based on the embodiments and the accompanying drawings. However, the scope of the present invention is not limited by the above embodiments and drawings, and the scope of the present invention will be limited only by the contents described in the claims set forth below.

[0110] The present invention relates to a manufacturing method for laminating an insulating sheet and an ultra-thin copper foil, and a multilayer structure based thereon. In particular, it exhibits excellent electrical properties and thermal stability, making it suitable for use in various electronic devices and advanced industrial fields.

Claims

1. a) A peeling layer coating step for forming a peeling layer (200) on a carrier film (300); b) A peeling layer surface treatment step of forming fine irregularities (210) by plasma treatment on the surface of the peeling layer; c) A physical vapor deposition step of forming a copper foil (100) by repeating the process of forming a copper foil layer (111) on the peeling layer by a physical vapor deposition process at a selected speed and number of times; d) an etching step of coating a photoresist on the copper foil, etching it, and forming a copper foil pattern (110); e) an insulating layer coating step of forming an insulating layer (410) that supports the copper foil pattern by filling the space where the copper foil pattern is formed with resin; f) a release film coating step of attaching a release film (420) to the insulating layer; a method for manufacturing an ultra-thin copper foil structure laminated with an insulating sheet.

2. A method of bonding an ultra-thin copper foil structure manufactured according to claim 1 to a core, g) a step of removing a carrier film including a release film and a release layer of a first electrode copper foil structure, and laminating a first insulating layer so that a first copper foil pattern corresponds to a core disposed on the lower side; h) a step of removing a carrier film including a release film and a release layer of a second electrode copper foil structure, and laminating a second insulating layer on a first insulating layer such that the second copper foil pattern corresponds to the first copper foil pattern on the lower side and the core on the upper side; i) a step of pressing the stacked lower core, the first insulating layer and the first copper foil pattern, the second insulating layer and the second copper foil pattern, and the upper core, and fixing the multilayer structure by the bonding force of the insulating layers; a method for forming a multilayer structure comprising.

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