Patent Description:
The present invention relates to an FPCB and a method for manufacturing the same, and more specifically, to an FPCP which does not require a fuse to be mounted thereon, thereby reducing the total volume and saving costs, and a method for manufacturing the same.

A printed circuit board (PCB) is widely used in various electronic products such as TVs, computers, mobile phones, displays, communication networks, and semiconductor modules. As a type of such PCB, a flexible printed circuit board (FPCB) with flexibility in particular has recently been widely used.

In general, an FPCB is manufactured by laminating a copper foil on a polyimide film to form a copper clad laminate, laminating a dry film thereon to form a conductor pattern though exposure, development, and etching processes, and then attach a cover lay on the outermost copper foil. The FPCB is installed in a bent state inside a complex product case by utilizing the flexibility of raw materials or is used at a repeatedly moving portion, and due to the properties thereof, is used in various manners in miniaturization (digital cameras, camcorders, etc.), flexibility (printer heads, hard disks, etc.), high-density wires (precision instruments such as medical devices), and rationalization of assembly (measuring instruments, vehicle electronics, battery modules, etc.).

The FPCB is formed by etching and the like, and thus, does not occupy a large volume, and does not frequently cause problems such as disconnection due to an external impact. However, elements such as a fuse are mounted on the FPCB separately through a mounting process after the FPCB is completely manufactured. Therefore, there have been problems in that the total volume of the FPCB increases, and costs also increase.

An object of the present invention for solving the above problems is to provide an FPCB which does not require a fuse to be mounted thereon, thereby reducing the total volume and saving costs, and a method for manufacturing the same.

Problems to be solved by the present invention are not limited to the above-mentioned problem, and other problems that are not mentioned may be apparent to those skilled in the art from the following description.

In an FPCB including a pattern circuit layer according to an embodiment of the present invention for achieving the above objects, the pattern circuit layer has a pattern fuse embedded therein, and the pattern fuse includes: a first conductive wire made of a metal and having a spiral structure; and a second conductive wire made of a metal and having a spiral structure, wherein the first conductive wire and the second conductive wire have a double helix structure.

In addition, the first conductive wire may include: a first lower conductive wire formed on a bottom surface of the pattern circuit layer; a first upper conductive wire formed on an top surface of the pattern circuit layer; and a first via conductive wire configured to connect the first lower conductive wire and the first upper conductive wire to each other, and the second conductive wire may include: a second lower conductive wire formed on the bottom surface of the pattern circuit layer; a second upper conductive wire formed on the top surface of the pattern circuit layer; and a second via conductive wire configured to connect the second lower conductive wire and the second upper conductive wire to each other.

In addition, the first conductive wire and the second conductive wire may have a quadrangular shape and a double helix structure.

In addition, each of the first lower conductive wire, the second lower conductive wire, the first upper conductive wire, and the second upper conductive wire may be formed to have a linear shape.

In addition, each of the first via conductive wire and the second via conductive wire may be formed to have a linear shape in a thickness direction on the pattern circuit layer.

In addition, each of the first conductive wire and the second conductive wire may have a start terminal and an end terminal, which are exposed on only one of the top surface or the bottom surface of the pattern circuit layer.

In addition, the start terminal of the first conductive wire and the start terminal of the second conductive wire may be separately formed, and the end terminal of the first conductive wire and the end terminal of the second conductive wire may also be separately formed.

In addition, the start terminal of the first conductive wire and the start terminal of the second conductive wire may be formed connected to each other, and the end terminal of the first conductive wire and the end terminal of the second conductive wire may be formed connected to each other.

In addition, each of the first conductive wire and the second conductive wire may have the start terminal connected to a power bus bar and the end terminal connected to a sensing bus bar.

In addition, the end terminal of the first conductive wire may be connected to a first sensing bus bar, and the end terminal of the second conductive wire may be connected to a second bus bar.

In addition, the metal may include at least one of silver, copper, gold, or aluminum.

In addition, a cover lay may be further laminated on the top surface of the pattern circuit layer.

A method for manufacturing an FPCB according to the present invention for achieving the above objects is defined in claim <NUM>. The method includes: forming a first lower conductive wire and a second lower conductive wire on an top surface of a base film; exposing both ends of the first lower conductive wire and the second lower conductive wire, and laminating a micro-pillar on the top surface of the base film; forming a first via conductive wire and a second via conductive wire on both the ends of the first lower conductive wire and the second lower conductive wire, respectively; injecting a filler into an empty space in which the micro-pillar is not filled on the top surface of the base film; and forming a first upper conductive wire connecting the first via conductive wires to each other and a second upper conductive wire connecting the second via conductive wires to each other on an top surface of the micro-pillar.

In addition, in the forming of the first lower conductive wire and the second lower conductive wire, the first lower conductive wire and the second lower conductive wire may be formed parallel to a first direction.

In addition, in the forming of the first upper conductive wire and the second upper conductive wire, the first upper conductive wire and the second upper conductive wire may be formed parallel to a second direction.

In addition, the first direction and the second direction may be directions different from each other.

In addition, in the forming of the first lower conductive wire and the second lower conductive wire, the first lower conductive wire and the second lower conductive wire may be formed on the top surface of the base film by at least one of an etching or printing method.

In addition, in the forming of the first upper conductive wire and the second upper conductive wire, the first upper conductive wire and the second upper conductive wire may be formed on the top surface of the micro-pillar by at least one of an etching or printing method.

In addition, after the forming of the first upper conductive wire and the second upper conductive wire, a first conductive wire including the first lower conductive wire, the first via conductive wire, and the first upper conductive wire, and a second conductive wire including the second lower conductor, the second via conductor, and the second upper conductor may each have a start terminal formed at a start portion, and an end terminal formed at an end portion.

In addition, the first conductive wire and the second conductive wire may have the start terminal and the end terminal, which are exposed only on one of an top surface or a bottom surface of a pattern circuit layer.

Other specific details of the present invention are included in the detailed description and drawings.

According to the embodiments of the present invention, there are at least the following effects.

Since the pattern fuse having the double helix structure is formed on the FPCB using the through polymer via (TPV) method rather than the mounting method and the like, it is possible to reduce the total volume of the FPCB and save the costs.

Effects according to the present invention are not limited by the contents exemplified above, and more various effects are included herein.

Advantages and features of the inventive concept and methods of accomplishing the same may be understood more readily by reference to the following detailed description of exemplary embodiments and the accompanying drawings. The inventive concept may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art to which the inventive concept pertains. The inventive concept will only be defined by the appended claims. The same reference numerals refer to like elements throughout the specification.

Unless otherwise defined, all the terms used herein (including technical and scientific terms) will be used in a sense that can be commonly understood to those of ordinary skill in the art to which the inventive concept pertains. In addition, the terms that are defined in a commonly used dictionary are not interpreted ideally or excessively unless specifically defined.

The terms used herein are for the purpose of describing embodiments and are not intended to be limiting of the present invention. In the present disclosure, singular forms include plural forms unless the context clearly indicates otherwise. As used herein, the terms "comprises" and/or "comprising" are intended to be inclusive of the stated elements, and do not exclude the possibility of the presence or the addition of one or more other elements.

<FIG> is a perspective view of a FPCB <NUM> which has a pattern fuse <NUM> embedded therein according to an embodiment of the present invention.

According to an embodiment of the present invention, since the pattern fuse <NUM> having a double helix structure is formed on the FPCB <NUM> using a through polymer via (TPV) method rather than a mounting method and the like, it is possible to reduce the total volume of the FPCB <NUM> and save costs.

To this end, in the FPCB <NUM> including a pattern circuit layer <NUM> according to an embodiment of the present invention, the pattern circuit layer <NUM> has the pattern fuse <NUM> embedded therein, and the pattern fuse <NUM> includes a first conductive wire <NUM> made of a metal and spirally formed, and a second conductive wire <NUM> made of a metal and spirally formed. The first conductive wire <NUM> and the second conductive wire <NUM> have a double helix structure.

As illustrated in <FIG>, the pattern fuse <NUM> according to an embodiment of the present invention includes the first conductive wire <NUM> and the second conductive wire <NUM>. The first conductive wire <NUM> is made of a metal, and is embedded in the pattern circuit layer <NUM> of the FPCB <NUM>. In addition, the second conductive wire <NUM> is also made of a metal, and is embedded in the pattern circuit layer <NUM> of the FPCB <NUM>. Both the first conductive wire <NUM> and the second conductive wire <NUM> have spiral structures, and particularly, a double helix structure.

Specifically, the first conductive wire <NUM> includes a first lower conductive wire <NUM>, a first upper conductive wire <NUM>, and a first via conductive wire <NUM>. The first lower conductive wire <NUM> is formed to have a linear shape on a bottom surface of the pattern circuit layer <NUM>, and the first upper conductive wire <NUM> is formed to have a linear shape on a top surface of the pattern circuit layer <NUM>. In addition, the first via conductive wire <NUM> connects the first lower conductive wire <NUM> and the first upper conductive wire <NUM> to each other, and is formed to have a linear shape in a thickness direction on the pattern circuit layer <NUM>. Since the first lower conductive wire <NUM>, the first upper conductive wire <NUM>, and the first via conductive wire <NUM> each have the linear shape as described above, the first conductive wire <NUM> may have a quadrangular shape. In addition, since the first lower conductive wire <NUM>, the first via conductive wire <NUM>, and the first upper conductive wire <NUM> are sequentially connected and repeatedly formed, the first conductive wire <NUM> may have the spiral structure.

In the same manner, the second conductive wire <NUM> includes a second lower conductive wire <NUM>, a second upper conductive wire <NUM>, and a second via conductive wire <NUM>. The second lower conductive wire <NUM> is formed to have a linear shape on the bottom surface of the pattern circuit layer <NUM>, and the second upper conductive wire <NUM> is formed to have a linear shape on the top surface of the pattern circuit layer <NUM>. In addition, the second via conductive wire <NUM> connects the second lower conductive wire <NUM> and the second upper conductive wire <NUM> to each other, and is formed to have a linear shape in the thickness direction on the pattern circuit layer <NUM>. Since the second lower conductive wire <NUM>, the second upper conductive wire <NUM>, and the second via conductive wire <NUM> each have the linear shape as described above, the second conductive wire <NUM> may have a quadrangular shape. In addition, since the second lower conductive wire <NUM>, the second via conductive wire <NUM>, and the second upper conductive wire <NUM> are sequentially connected and repeatedly formed, the second conductive wire <NUM> may have the spiral structure.

The first conductive wire <NUM> and the second conductive wire <NUM> are not separately formed, but rather spirally formed in the state of overlapping each other, that is, have the double helix structure. In addition, the metal for forming the first conductive wire <NUM> and the second conductive wire <NUM> may include at least one of silver, copper, gold, or aluminum which has high electrical conductivity, and particularly, may preferably include copper, which is easy to be molded, has a low price, and is economical.

<FIG> is a flowchart illustrating a method for manufacturing the FPCB <NUM> which has the pattern fuse <NUM> embedded therein according to an embodiment of the present invention.

A method for manufacturing the FPCB <NUM> according to an embodiment of the present invention includes a process of forming a first lower conductive wire <NUM> and a second lower conductive wire <NUM> on a top surface of a base film <NUM>; a process of exposing both ends of the first lower conductive wire <NUM> and the second lower conductive wire <NUM>, and laminating a micro-pillar <NUM> on the top surface of the base film <NUM>; a process of forming the first via conductive wire <NUM> and the second via conductive wire <NUM> on both the ends of the first lower conductive wire <NUM> and the second lower conductive wire <NUM>, respectively; a process of injecting a filler <NUM> into an empty space in which the micro-pillar <NUM> is not filled on the top surface of the base film <NUM>, and a process of forming the first upper conductive wire <NUM> connecting the first via conductive wires <NUM> to each other and the second upper conductive wire <NUM> connecting the second via conductive wires <NUM> to each to other on a top surface of the micro-pillar <NUM>.

Hereinafter, each step illustrated in the flow chart of <FIG> will be described in detail with reference to <FIG>.

<FIG> is a schematic side view illustrating a state in which a first lower conductive wire <NUM> and a second lower conductive wire <NUM> are formed on a base film <NUM> according to an embodiment of the present invention, and <FIG> is a schematic top view illustrating the state in which the first lower conductive wire <NUM> and the second lower conductive wire <NUM> are formed on the base film <NUM> according to an embodiment of the present invention.

First, the base film <NUM> is prepared, and as illustrated in <FIG>, the first lower conductive wire <NUM> and the second lower conductive wire <NUM> are formed on an top surface of the base film <NUM> (S201). The base film <NUM> may be a film containing silicon. In addition, the first lower conductive wire <NUM> and the second lower conductive wire <NUM> may be formed on the top surface of the base film <NUM> by at least one of an etching or printing method.

The first lower conductive wire <NUM> and the second lower conductive wire <NUM> are each provided in plurality, and may be formed parallel to a first direction. In addition, the first direction may have, for example, as illustrated in <FIG>, a predetermined inclination with respect to the base film <NUM>. In addition, the first lower conductive wire <NUM> and the second lower conductive wire <NUM> may be alternately formed with each other. Therefore, later, the first conductive wire <NUM> and the second conductive wire <NUM> may have the double helix structure.

<FIG> is a schematic side view illustrating a state in which a micro-pillar <NUM> is formed on the base film <NUM> according to an embodiment of the present invention, and <FIG> is a schematic top view illustrating the state in which the micro-pillar <NUM> is formed on the base film <NUM> according to an embodiment of the present invention.

When the first lower conductive wire <NUM> and the second lower conductive wire <NUM> are formed, both the ends of the first lower conductive wire <NUM> and the second lower conductive wire <NUM> are exposed as illustrated in <FIG>, and the micro-pillar <NUM> is laminated on the top surface of the base film <NUM> (S202). At this time, the micro-pillar <NUM> are provided in plurality, and as illustrated in <FIG>, and may be formed parallel to a second direction which is different from the first direction. In addition, later, the first upper conductive wire <NUM> and the second upper conductive wire <NUM> are formed along the micro-pillar <NUM>. Therefore, ends of different first lower conductive wires <NUM> may be disposed on both the ends of one micro-pillar <NUM>, respectively, or ends of different second lower conductive wires <NUM> may be disposed on both the ends of one micro-pillar <NUM>, respectively.

In order to laminate the micro-pillar <NUM>, a thick photoresist may be first laminated and then patterned. The micro-pillar <NUM> may be an epoxy-based SU-<NUM> negative photoresist which is crosslinked by ultraviolet rays and of which remaining portions are washed to facilitate the patterning.

Meanwhile, although not shown in the drawings, after the micro-pillar <NUM> is laminated, a separate seed layer may be formed to activate the micro-pillar <NUM>. In order to form the seed layer, a physical vapor deposition (PVD) method may be used, or an atomic layer deposition (ALD) method may be used. In addition, the seed layer may include nitride titanium (TiN) having electrical conductivity, good adhesion to a metal, and a low processing temperature.

<FIG> is a schematic side view illustrating a state in which a first via conductive wire <NUM> and a second via conductive wire <NUM> are formed on the base film <NUM> according to an embodiment of the present invention.

After the micro-pillar <NUM> is laminated, the first via conductive wire <NUM> and the second via conductive wire <NUM> may be respectively formed at both the ends of the first lower conductive wire <NUM> and the second lower conductive wire <NUM> S203. As described above, ends of different first lower conductive wires <NUM> may be disposed on both the ends of the micro-pillar <NUM>, respectively, or ends of different second lower conductive wire <NUM> may be disposed on both the ends of the micro-pillar <NUM>, respectively. Therefore, when the first via conductive wire <NUM> and the second via conductive wire <NUM> are formed, as illustrated in <FIG>, the first via conductive wire <NUM> and the second via conductive wire <NUM> may be formed along sidewalls of both the ends of the micro-pillar <NUM>.

In order to form the first via conductive wire <NUM> and the second via conductive wire <NUM>, the micro-pillar <NUM> may be subjected to electroless plating with a metal such as copper. In addition, in order to prevent corrosion of the metal, electrolytic plating may be additionally performed with a metal having low ionization tendency.

Each of the first via conductive wire <NUM> and the second via conductive wire <NUM> is also made of a metal, and when the first conductive wire <NUM> and the second conductive wire <NUM> are formed later, the first via conductive wire <NUM> and the second via conductive wire <NUM> respectively connect the lower conductive wires <NUM> and <NUM> and the upper conductive wires <NUM> and <NUM>, and thus, serve as a through electrode configured to electrically connect the bottom surface and the top surface of the pattern circuit layer <NUM> to each other.

<FIG> is a schematic side view illustrating a state in which a filler <NUM> is injected into the base film <NUM> according to an embodiment of the present invention, and <FIG> is a schematic top view illustrating the state in which the filler <NUM> is injected into the base film <NUM> according to an embodiment of the present invention.

As illustrated in <FIG> and <FIG>, on the top surface of the base film <NUM>, the filler <NUM> is injected into an empty space in which the micro-pillar <NUM> is not filled (S204). The filler <NUM> may be an epoxy molding composition (EMC) having electrical insulation. Thereby, the micro-pillar <NUM> may be encapsulated inside the insulator.

<FIG> is a schematic top view illustrating a state in which a first upper conductive wire <NUM> and a second upper conductive wire <NUM> are formed according to an embodiment of the present invention.

On the top surface of the micro-pillar <NUM>, the first upper conductive wire <NUM> connecting the first via conductive wires <NUM> to each other and the second upper conductive wire <NUM> connecting the second via conductive wires <NUM> to each other are formed S205. In addition, the first upper conductive wire <NUM> and the second upper conductive wire <NUM> may be formed on the top surface of the base film <NUM> by at least one of an etching or printing method.

The first upper conductive wire <NUM> and the second upper conductive wire <NUM> are all formed along the micro-pillar <NUM>. That is, the first upper conductive wire <NUM> may be formed on the top surface of the micro-pillar <NUM> on which the first via conductive wire <NUM> is formed, while connecting the first via conductive wires <NUM> to each other, the second upper conductive wire <NUM> may be formed on the top surface of the micro-pillar <NUM> on which the second via conductive wire <NUM> is formed, while connecting the first via conductive wires <NUM> to each other. At this time, the first upper conductive wire <NUM> and the second upper conductive wire1023 may be formed to be wider than the first via conductive wire <NUM> and the second via conductive wire <NUM> to be connected to the first via conductive wire <NUM> and the second via conductive wire <NUM>, respectively.

As described above, ends of different first lower wires <NUM> may be disposed on both the ends of one micro-pillar <NUM>, respectively, or ends of different second lower wires <NUM> may be disposed on both the ends of one micro-pillar <NUM>, respectively. Therefore, the first upper conductive wire <NUM> is connected to each of the different first lower conductive wires <NUM> through the first via conductive wire <NUM>, and the second upper conductive wire <NUM> is connected to each of the different second lower conductive wires <NUM> through the second via conductive wire <NUM>, so that the first conductive wire <NUM> and the second conductive wire <NUM> may be spirally formed.

The first upper conductive wire <NUM> and the second upper conductive wire <NUM> are each provided in plurality, and are all formed along the micro-pillar <NUM>, and thus, may be formed parallel to the second direction. It is preferable that the second direction is a direction different from the first direction. For example, as illustrated in <FIG>, the second direction may have a predetermined inclination with respect to the first direction. In addition the first upper conductive wire <NUM> and the second upper conductive wire <NUM> may be alternately formed with each other. Therefore, in the pattern circuit layer <NUM> of the FPCB <NUM>, the pattern fuse <NUM> including the first conductive wire <NUM> and the second lead <NUM> having a double helix structure may be formed embedded. Furthermore, after the pattern fuse <NUM> is formed, the base film <NUM> may be removed.

Meanwhile, although not illustrated in the drawings, in order to protect a circuit pattern of the FPCB <NUM>, a cover lay may be laminated on the top surface of the micro-pillar <NUM>. The cover lay may be a film of a polyimide-based material.

<FIG> is a perspective view illustrating a state in which start terminals <NUM> and <NUM> and end terminals <NUM> and <NUM> are formed on a first conductive wire <NUM> and a second conductive wire <NUM> according to an embodiment of the present invention.

After the first upper conductive wire <NUM> and the second upper conductive wire <NUM> are formed, the start terminals <NUM> and <NUM> are formed at start portions of the first conductive wire <NUM> and the second conductive wire <NUM>, and the end terminals <NUM> and <NUM> are formed at end portions thereof. At this time, the first conductive wire <NUM> and the second conductive wire <NUM> may have the start terminals <NUM> and <NUM> and the end terminals <NUM> and <NUM> all exposed only on one of the top surface or the bottom surface of the pattern circuit layer <NUM>.

In addition, according to an embodiment of the present invention, the first conductive wire <NUM> and the second conductive wire <NUM> have the start terminals <NUM> and <NUM> and the end terminals <NUM> and <NUM> all separately formed. That is, as illustrated in <FIG>, at the start portion of the first conductive wire <NUM>, a first start terminal <NUM> is formed, and at the start portion of the second conductive wire <NUM>, a second start terminal <NUM> is separately formed. In addition, at the end portion of the first conductive wire <NUM>, a first end terminal <NUM> is formed, and at the end portion of the second conductive wire <NUM>, a second end terminal <NUM> is separately formed.

<FIG> is a schematic view illustrating a state in which bus bars <NUM> and <NUM> are connected to the pattern fuse <NUM> according to an embodiment of the present invention.

If at least one of the first start terminal <NUM>, the second start terminal <NUM>, the first end terminal <NUM>, or the second end terminal <NUM> is exposed on another surface of the patter circuit layer <NUM>, in order to be connected to the bus bars <NUM> and <NUM>, the upper and bottom surfaces of the FPCB <NUM> should be bent to be inverted from each other. Then, a process of bending the FPCB <NUM> should be further added, and there is also a problem in that the durability of a bent portion is degraded to cause lifespan to be shortened.

The first start terminal <NUM> of the first conductive wire <NUM> and the second start terminal <NUM> of the second conductive wire <NUM> are, as illustrated in <FIG>, connected to one power bus bar <NUM>. However, according to an embodiment of the present invention, the first start terminal <NUM> and the second start terminal <NUM> are all exposed on the same surface of the pattern circuit layer <NUM>, so that when connected to the power bus bar <NUM>, the top surface and the bottom surface of the FPCB <NUM> are not required to be bent to be inverted from each other.

In addition, the first end terminal <NUM> of the first conductive wire <NUM> and the second end terminal <NUM> of the second conductive wire <NUM> are connected to different sensing bus bars <NUM> and <NUM>, respectively. However, the first end terminal <NUM> and the second end terminal <NUM> are all exposed on the same surface of the pattern circuit layer <NUM>, so that when connected to the sensing bus bar <NUM>, the top surface and the bottom surface of the FPCB <NUM> are not required to be bent to be inverted from each other.

<FIG> is a perspective view illustrating the state in which a start terminal <NUM> and an end terminal <NUM> are formed on the first conductive wire <NUM> and the second conductive wire <NUM> according to another embodiment of the present invention.

According to another embodiment of the present invention, the first conductive wire <NUM> and the second conductive wire <NUM> have the start terminal <NUM> and the end terminal <NUM> formed respectively connected to each other. That is, as illustrated in <FIG>, a first start terminal formed in a start portion of the first conductive wire <NUM> and a second start terminal formed in a start portion of the second conductive wire <NUM> are formed connected to each other. In addition, a first end terminal formed in an end portion of the first conductive wire <NUM> and a second end terminal formed in an end portion of the second conductive wire <NUM> are formed connected to each other. Particularly, as illustrated in <FIG>, the first start terminal and the second start terminal may be integrally formed as one start terminal <NUM>, and the first end terminal and the second end terminal may be integrally formed as one end terminal <NUM>. However, the present invention is not limited thereto. The first start terminal and the second start terminal and the first end terminal and the second end terminal may be separately formed and then bonded to each other through a separate bonding part (not shown), or may be connected to each other through welding or an adhesive. In addition, the first conductive wire <NUM> and the second conductive wire <NUM> may have the start terminal <NUM> and the end terminal <NUM> all exposed only on one of the top surface or the bottom surface of the pattern circuit layer <NUM>.

<FIG> is a schematic view illustrating a state in which bus bars 21a and 22a are connected to a pattern fuse 100a according to another embodiment of the present invention.

The start terminals <NUM> of the first conductive wire <NUM> and the second conductive wire <NUM> are formed connected to each other, and thus, are connected to one power bus bar 21a as illustrated in <FIG>. However, the first start terminal and the second start terminal are all exposed on the same surface of the pattern circuit layer <NUM> and then connected to each other, so that when connected to the power bus bar 21a, an top surface and a bottom surface of an FPCB 1a are not required to be bent to be inverted from each other.

Claim 1:
An flexible printed circuit board FPCB (<NUM>) comprising a pattern circuit layer (<NUM>),
wherein the pattern circuit layer (<NUM>) has a pattern fuse (<NUM>) embedded therein,
characterised in that
the pattern fuse (<NUM>) comprises:
a first conductive wire (<NUM>) made of a metal and having a spiral structure; and
a second conductive wire (<NUM>) made of a metal and having a spiral structure,
wherein the first conductive wire (<NUM>) and the second conductive wire (<NUM>) have a double helix structure.