WO2019013566A1

WO2019013566A1 - Functional contactor

Info

Publication number: WO2019013566A1
Application number: PCT/KR2018/007905
Authority: WO
Inventors: 임병국; 공동훈; 문지우
Original assignee: 주식회사 아모텍
Priority date: 2017-07-12
Filing date: 2018-07-12
Publication date: 2019-01-17
Also published as: KR20190007233A; KR102442279B1

Abstract

Disclosed is a functional contactor. The functional contactor according to an exemplary embodiment of the present invention comprises: a conductor having elasticity and in contact with a conductor of an electronic device; a functional element which is connected to the conductor having elasticity and has a first electrode and a second electrode on at least a part of an upper surface and a lower surface, respectively; and a solder for bonding a lower surface of the conductor having elasticity to the first electrode of the functional element. Here, the conductor having elasticity has at least one through hole in a terminal portion facing the functional element, and the solder includes a wedge portion which is inserted and fixed into the conductor having elasticity through the at least one through hole.

Description

Functional Contactor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contactor for an electronic device such as a smart phone, and more particularly to a functional contactor capable of improving the bonding strength of a contactor stacked by soldering on a functional device.

In recent portable electronic devices, there is an increasing tendency to adopt a metal housing to improve esthetics and robustness. Such a portable electronic device reduces the external impact and reduces the electromagnetic waves leaking from or leaking into the portable electronic device, and provides an elasticity such as a conductive gasket or a conductive contactor for electrical contact between the antenna disposed in the external housing and the built- Is used.

However, when static electricity having an instantaneous high voltage is input through a conductor such as an outer metal housing, static electricity flows into the built-in circuit board through the elastic conductor to break the circuit of the IC and the like, Leakage current is propagated along the ground of the circuit to the external housing to cause discomfort to the user or severe shock, resulting in an electric shock which may cause injury to the user.

A functional element for protecting the user from such static electricity or leakage current is provided together with a conductive gasket or a conductive contactor for connecting the metal housing and the circuit board, There is a need for a functional contactor having various functions for protecting a circuit in a portable electronic device or for smoothly transmitting a communication signal.

Moreover, such a functional contactor laminates a conductor having elasticity to the electrode of the functional device by soldering, wherein the bond strength between the conductor having elasticity by the solder and the functional device does not ensure sufficient reliability, A large amount of product defects occur as they are separated from the functional elements.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a functional contactor having a coupling member using solder and capable of increasing a coupling strength between a functional element and a conductor having elasticity.

In order to solve the above-mentioned problems, the present invention provides an electronic device comprising: a conductor having elasticity to be brought into contact with a conductor of an electronic device; A functional element connected to the elastic conductor and having a first electrode and a second electrode on at least a part of an upper surface and a lower surface, respectively; And a solder connecting the lower surface of the conductor having elasticity and the first electrode of the functional device. Here, the elastic conductor includes at least one through hole in a terminal portion opposite to the functional element, and the solder includes a wedge portion inserted and fixed to the elastic conductor through the at least one through hole.

According to a preferred embodiment of the present invention, a part of the wedge portion may be formed larger than the diameter of the at least one through hole.

The elastic conductor may be plated with a metal on one surface of the terminal portion facing the functional element, an inner wall of the at least one through hole, and a portion of the other surface of the terminal portion.

At this time, a portion of the upper surface of the terminal portion adjacent to the inner wall of the through hole may be plated.

Here, the metal may be Sn.

The through holes may be formed in a plurality of holes and may be provided symmetrically with respect to the center of the terminal portions.

As another example, the through holes may be formed in a plurality of points and may be provided in point symmetry with respect to the center of the terminal portions.

As another example, the through holes may be formed in the center and on both sides of the terminal portion.

The first electrode and the second electrode may be provided on the upper surface and the lower surface of the functional device.

Further, the elastic conductor includes: a clip-shaped contact portion which contacts the conductor of the electronic device; And a bent portion having a predetermined curvature to impart an elastic force.

In addition, the elastic conductor may further include a side wall extending vertically from the terminal portion at the long side.

At this time, the side wall may extend at least a part of the short side where the bending portion is not formed.

Further, the bent portion may extend from the terminal portion.

As another example, the bent portion may be spaced apart from the terminal portion by a predetermined distance.

The functional device may include an electric shock prevention function for blocking a leakage current of an external power source flowing from the ground of the circuit board of the electronic device, a communication signal transmitting function for passing a communication signal flowing into the conductive case or from the circuit board, And an ESD protection function of passing the static electricity from the conductive case by discharging the static electricity from the conductive case.

According to the present invention, since at least one through hole is provided in the lower portion of the elastic conductor and the solder is introduced into the through hole to form the wedge portion, an additional coupling structure can be provided by the solder, The bonding strength between the conductors can be increased and the reliability of the product can be improved.

1 is a perspective view of a functional contactor according to an embodiment of the present invention,

Fig. 2 is a sectional view of Fig. 1,

Fig. 3 is a plan view showing the lower part of the elastic body having the elasticity in Fig. 1,

FIG. 4 is a cross-sectional view illustrating a state before coupling of a conductor having elasticity and a functional device in a process of manufacturing a functional contactor according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view illustrating a state where a conductor having elasticity and a functional device are combined with each other in the course of manufacturing a functional contactor according to an embodiment of the present invention,

6 is an enlarged cross-sectional view of a portion A in Fig. 5

7 is an enlarged cross-sectional view of a state where a wedge portion is formed by solder at portion A of FIG. 5,

8 is a plan view showing another example of the through hole in the functional contactor according to the embodiment of the present invention,

9 is a plan view showing another example of the through hole in the functional contactor according to the embodiment of the present invention,

10 is a perspective view showing another example of a conductor having elasticity in a functional contactor according to an embodiment of the present invention,

11 is a cross-sectional view of the functional contactor to which the elastic conductor of Fig. 10 is applied.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

The functional contactor 100 according to an embodiment of the present invention includes a conductor 110 having an elasticity, a functional device 120, and a solder 130, as shown in FIGS.

Such a functional contactor 100 is for electrically connecting a conductive case such as an external metal case to a circuit board or a conductive bracket electrically coupled to a circuit board on one side in a portable electronic device.

At this time, the functional contactor 100 may be configured such that the elastic conductor 110 contacts the circuit board or the conductive bracket, and the functional element 120 can be coupled to the conductive case, And the functional device 120 may be coupled to the circuit board.

For example, if the functional contactor 100 is of the SMT type, i.e., coupled through soldering, then the functional element 120 is coupled to the circuit board, and if it is an adhesive layer type, , The functional device 120 may be coupled to the conductive case.

Meanwhile, the portable electronic device may be a portable terminal such as a smart phone, a cellular phone, and the like, and may be a smart watch, a digital camera, a DMB, an electronic book, a netbook, a tablet PC, Such electronic devices may comprise any suitable electronic components including antenna structures for communication with external devices.

Here, the conductive case may be an antenna for communication between the portable electronic device and an external device. Such a conductive case may be provided, for example, to partially surround or partially surround the sides of the portable electronic device.

The resilient conductor 110 is in electrical contact with the conductor of the electronic device and has an elastic force. In one example, the resilient conductor 110 may be in electrical contact with a circuit board of the electronic device, a bracket coupled to the circuit board, and a human contactable conductor, such as a case.

Here, when the conductor 110 having elasticity contacts the conductor, the conductor 110 having elasticity can be contracted toward the functional device 120 by the pressing force, and when the conductor is separated, Can be restored to its original state.

On the other hand, when the elastic conductor 110 is pressed, galvanic corrosion occurs due to the potential difference between the dissimilar metals when exposed to the corrosive environment. At this time, in order to minimize galvanic corrosion, it is preferable that the contact area of the conductor 110 having elasticity is made small.

One side of the conductor 110 having such elasticity is in contact with the conductor of the electronic device and the other side thereof is electrically connected to the functional device 120 and the lower side thereof is formed of the long side 115a and the short side 115b. That is, the conductor 110 having elasticity may be a rectangle whose bottom surface is longer than one side of the length of one side.

The functional device 120 is electrically connected in series to the elastic conductor 110, and the first electrode 121 and the second electrode 122 are provided on at least a part of the upper surface and the lower surface, respectively.

For example, the first electrode 121 and the second electrode 122 may be provided on a top surface and a bottom surface of the functional device 120, respectively. That is, the body between the first electrode 121 and the second electrode 122 may protrude outwardly from the first electrode 121 and the second electrode 122.

As another example, the first electrode 121 and the second electrode 122 may be formed to have a large area in order to increase the capacity of the capacitance. That is, the first electrode 121 and the second electrode 122 may be formed over the entire upper surface and the lower surface of the functional device 120.

At this time, the first electrode 121 may be laminated with a conductor 110 having elasticity, and the second electrode 122 may be coupled to a circuit board through soldering or may be coupled to a conductor such as a conductive case through a conductive adhesive layer .

The solder 130 is used to connect the elastic conductive conductor 110 and the functional device 120 to connect the lower surface of the elastic conductive conductor 110 and the first electrode 121 of the functional device 120 do.

The solder 130 may be formed by applying a solder paste to the first electrode 121, placing the resilient conductor 110 on the solder paste in the soldering process, and then heating the melted solder paste, The lower electrode 110 and the first electrode 121 of the functional device 120 are bonded to each other so that the functional device 120 and the conductor 110 having elasticity can be coupled to each other.

In addition, the elastic conductor 110 is provided with at least one through hole 116 in the lower portion thereof. Here, a lower portion of the elastic conductor 110 may be a terminal portion 115 as described later, and the through hole 116 may be provided in the terminal portion 115, as shown in FIGS. 2 and 3.

Although the through holes 116 may be formed as a single unit, it is preferable that a plurality of the through holes 116 are formed to ensure a uniform bonding force to the whole of the elastic conductor 110.

For example, the through hole 116 may be provided symmetrically with respect to the center of the terminal portion 115. Although the two through holes 116 are shown and described as being arranged symmetrically on both sides of the terminal portion 115 in Fig. 3, the number and position of the through holes 116 are not limited thereto.

At this time, the solder 130 includes a wedge portion 131 which is inserted and fixed to the elastic conductor 110 through at least one through hole 116. That is, the wedge part 131 is formed to be larger than the diameter of the at least one through hole 116, so that the wedge part 131 can be inserted and fixed into the elastic conductor 110.

More specifically, the wedge part 131 protrudes from the through hole 116 to the upper surface of the terminal part 115, that is, the upper surface of the terminal part 115, And is provided in an elongated form. Here, the wedge portion 131 can function as an additional coupling structure between the elastic conductive body 110 and the functional device 120.

The bonding strength between the elastic conductive member 110 and the functional device 120 is higher than the bonding strength of the solder 130 by the bonding of the terminal portion 115 of the conductor 110 having elasticity by the wedge portion 131 The bonding strength of the solder 130 alone can be compensated for, so that sufficient reliability can be assured for the bonding strength between the elastic conductor 110 and the functional device 120. Therefore, the conductor 110 having elasticity against external impact is prevented from being separated from the functional device 120, so that the reliability of the product can be improved.

The wedge portion 131 may be formed during the SMT process in which the conductor 110 having elasticity is mounted on the first electrode 121 on the upper surface of the functional device 120. First, the solder paste is coated on the first electrode 121 of the functional device 120 and heated in the same manner as in the usual case of soldering the conductor 110 having elasticity onto the functional device 120, The solder 130a of the first electrode 121 is formed on the first electrode 121 (see Fig. 4).

5, when the conductor 110 having elasticity is pressed on the molten solder 130a, the molten solder 130a passes through the through hole 116 to the upper surface of the terminal portion 115, that is, , And flows into the interior of the elastic conductor (110). The molten solder 130a rises to the upper surface of the terminal portion 115 through the through hole 116 by the urging force of the elastic conductor 110 and the upper portion 130b of the solder 130a again rises to the upper surface of the terminal portion 115 And flows in the horizontal direction (see Fig. 6).

7, the solder 130 is welded to the lower surface of the elastic conductor 110 and the first electrode 121 of the functional device 120, and the through hole 116 and the terminal And is welded to a part of the upper surface of the wedge portion 115 to form the wedge portion 131. The upper end portion 131a of the wedge portion 131 may extend from the upper surface of the terminal portion 115 to the periphery of the through hole 116 to be larger than the diameter of the through hole 116.

At this time, one surface of the terminal portion 115 opposed to the functional device 120, one surface of the at least one through hole 116, and the other surface of the terminal portion 115 are formed so that the molten solder 130a easily flows to the upper surface of the terminal portion 115 through the through- The inner wall and a portion 115c of the other surface of the terminal portion 115 can be plated with metal (see Figs. 6 and 7). Here, a portion 115c adjacent to the inner wall of the through hole 116 in the upper surface of the terminal portion 115 may be plated with metal.

That is, when the lower surface of the terminal portion 115 is plated with metal so as to facilitate soldering with the functional device 120, the elasticity of the conductor 110 having elasticity can be improved by the inner wall of the through hole 116 and a part of the upper surface of the terminal portion 115 Can be plated together. As described above, the metal plated on the lower surface of the terminal portion 115, the upper surface portion 115c of the terminal portion 115, and the inner wall of the through hole 116 may be Sn.

For this purpose, the lower surface of the terminal portion 115 may be plated after the lower surface of the terminal portion 115 is formed so as to form the through hole 116. The melted metal for the plating process flows to the inner wall of the through hole 116 and the upper surface portion 115c of the terminal portion 115 so that the inner wall of the through hole 116 and the terminal portion 115 may be also plated together.

This allows the molten solder 130a to flow easily along the inner wall of the through hole 116 to the upper portion 115c of the terminal portion 115 to stably form the wedge portion 131. [ In addition, the shape of the wedge portion 131 can be easily adjusted according to the length of the upper surface portion 115c of the terminal portion 115.

As shown in FIG. 8, the through holes 116 'may be provided in point symmetry with respect to the center of the terminal portion 115. For example, the through holes 116 'may be provided on diagonal lines around the edges facing each other on the lower surface of the terminal portion 115.

As a result, a uniform coupling force can be provided not only in the long side 115a of the elastic conductor 110 but also in the short side direction 115b. Therefore, the coupling between the elastic conductor 110 and the functional element 120 The strength can be further increased.

As another example, as shown in Fig. 9, three through-holes 116 " may be provided at the center and both sides of the terminal portion 115. [

At this time, the three through holes 116 may be formed to be substantially triangular so as to minimize the distance between the wedge portions 131 without increasing the number of the through holes 116 ", for example. The through hole 116 "is disposed at one side of the long side 115a at the center of the terminal portion 115 and one through hole 116" may be disposed at the other side of the long side 115a on both sides of the long side 115a .

Accordingly, the distance between the wedge portions 131 is minimized by minimizing the number of the through holes 116 ", thereby providing a uniform bonding force to the entirety of the elastic conductor 110, The coupling strength between the wedge part 131 provided on the flexible board 116 " can be increased, so that the bonding strength between the flexible conductor 110 and the functional device 120 can be further increased.

On the other hand, the elastic conductor 110 may include a contact portion 111, a bent portion 112, a spacing portion 113, an external portion 114, and a terminal portion 115 (see FIG. 1).

Here, the conductor 110 having elasticity may be a C-clip having a roughly " C-shaped " shape. Since the conductor 110 having such elasticity is in line contact or point contact, galvanic corrosion resistance can be excellent.

The contact portion 111 has a clip-like curved shape and can be in electrical contact with the conductor of the electronic device. The contact portion 111 may be disposed in the opening 114b provided on one side of the upper surface 114a of the covering portion 114 so that the curved portion protrudes outside the opening 114b.

The bent portion 112 extends from the contact portion 111 in a round shape and can have an elastic force. That is, the bent portion 112 may have a constant curvature to impart an elastic force. The bent portion 112 may be connected to the contact portion 111 at one end inside the elastic conductor 110 and at the other end to the upper surface 114a between the external portions 114.

The spacing portion 113 is a space formed between the lower end of the bending portion 112 and the side wall 114c of the covering portion 114. [ The bending portion 112 may be spaced apart from the terminal portion 115 by a predetermined distance. That is, the spacing portion 113 separates the bent portion 112 from the terminal portion 115 so as not to constrain the bent portion 112 that provides the elastic force. As a result, the elastic force of the contact portion 111 and the bent portion 112 may not be affected by the terminal portion 115.

The enclosure 114 may include an upper surface 114a, an opening 114b, and a side wall 114c.

The upper surface 114a is connected to the bent portion 112 and the side wall 114c and the contact portion 111 can be arranged from the inside to the outside of the opening 114b. The opening 114b may form a space through which the contact portion 111 flows according to the elastic force of the bent portion 112. [

The side wall 114c may extend vertically from the terminal portion 115 at the long side 115a. The side wall 114c may extend vertically from the terminal portion 115 to the short side 115b on which the bent portion 112 is not formed.

As a result, the external portion 114 can be formed in a case shape that surrounds the end portions of the contact portion 111 and the bent portion 112 from the outside so that the ends of the contact portion 111 and the bent portion 112 are not exposed to the outside .

As a result, the portion of the conductor 110 having elasticity can be minimized to the outside, so that it is possible to suppress the influence of external factors such as a hanging by the operator.

The terminal portion 115 corresponds to the lower surface of the elastic conductor 110 and may be formed to be connected to the lower portion of the outer casing 114. The terminal portion 115 may be a terminal that contacts the first electrode 121 of the functional device 120 and is electrically connected to the functional device 120.

The contact portion 111, the bent portion 112, the external portion 114, and the terminal portion 115 may be integrally formed of a conductive material having an elastic force.

Meanwhile, the functional device 120 may have a function for protecting a user or an internal circuit. In one example, the functional device 120 may include at least one of an electric shock protection device, a varistor, a suppressor, a diode, and a capacitor.

The functional device 120 may block the leakage current of the external power source flowing into the conductor from the ground of the circuit board. At this time, the functional device 120 may be configured such that the breakdown voltage Vbr or the breakdown voltage thereof is larger than the rated voltage of the external power supply of the electronic device. Here, the rated voltage may be a standard rated voltage for each country, for example, 240V, 110V, 220V, 120V, and 100V.

When the conductive case has an antenna function, the first electrode 121 and the second electrode 122 provided on the upper surface and the lower surface of the functional device 120 function as a capacitor to block leakage current of the external power source And a communication signal flowing from the conductor or the circuit board can be passed.

Furthermore, the functional device 120 can discharge the electrostatic discharge (ESD) flowing from the conductive case and allow it to pass through without being destroyed by insulation. At this time, the functional device 120 may be configured such that the breakdown voltage Vbr thereof is smaller than the dielectric breakdown voltage Vcp of the body provided between the first electrode 121 and the second electrode 122.

Accordingly, the functional contactor 100 electrically connects the conductive case and the circuit board with respect to a communication signal, an electrostatic discharge (ESD), etc., and passes the leakage current of the external power from the circuit board to the conductive case .

Meanwhile, the functional contactor 200 according to the embodiment of the present invention may include a conductor having elasticity in which the spacing portion is omitted. Hereinafter, the functional contactor 200 will be described with reference to FIG. 10, and the same parts as the functional contactor 100 described with reference to FIGS. 1 to 3 will not be described.

10, the elastic conductor 210 includes a contact portion 211, a bent portion 212, a side wall 214, and a terminal portion 215. [

The conductor 210 having such elasticity may be a C-clip having a roughly " C " shape. Since the conductor 210 having such elasticity is in line contact or point contact, galvanic corrosion resistance can be excellent.

The contact portion 211 has a clip-like curved shape and can be in electrical contact with the conductor of the electronic device. The contact portion 211 may be arranged to protrude outward between the side walls 214. [

The bent portion 212 extends in a round shape from the contact portion 211 and can have an elastic force. That is, the bent portion 212 may have a predetermined curvature to impart an elastic force. Here, the bent portion 212 may extend from the terminal portion 2115. That is, the bent portion 212 may be disposed between the contact portion 211 and the terminal portion 215.

At this time, the bent portion 212 may be exposed to the outside of the side wall 214, and the exposed portion may include a first electrode 121 and a solder 130 on a lower side thereof so as to flow without being fixed, (See FIG. 11).

The side wall 214 may extend vertically from the terminal portion 215 at the long side 215a. This side wall may extend to a portion 214a of the short side 215b where the bent portion 212 is not formed. That is, in the side wall 214, only a part 214a is formed on both sides of the side wall 214 at the short side 215b where the bent part 212 is not formed, so that a space is formed between the part 214a of the side wall 214 do. At this time, in the space between the portions 214a of the side wall 214, the contact portion 211 can flow by the elastic force of the bent portion 212. [

As a result, the portion of the conductor 210 having elasticity can be minimized to the outside, so that it is possible to suppress the influence of the external elements such as the latching by the operator.

The terminal portion 215 corresponds to the lower surface of the elastic conductive member 210 and may be formed to be connected to the lower side of the side wall 214. The terminal unit 215 may be a terminal that is coupled to the first electrode 221 of the functional device 220 by the solder 130 and is electrically connected to the functional device 220.

A through hole 216 may be formed in the terminal portion 215 and a wedge portion 131 may be formed on the upper surface of the through hole 216 and the terminal portion 215 by solder 130.

The contact portion 211, the bent portion 212, the side wall 214, and the terminal portion 215 may be integrally formed of a conductive material having an elastic force.

The functional contactor 200 may further include a functional device 220.

The functional device 220 is electrically connected in series to the elastic conductor 210, and the first electrode 221 and the second electrode 222 are provided on the upper surface and the lower surface, respectively.

The bent portion 212 of the elastic conductive member 210 is extended from the terminal portion 215 so that the first electrode 221 of the functional device 220 does not constrain the bent portion 212 that provides the elastic force, Is not formed at a position corresponding to the bent portion 212. [

That is, the first electrode 221 may be formed only on a part of the upper surface of the functional device 220 (see FIG. 11). At this time, the second electrode 222 may be formed only in a part of the lower surface corresponding to the first electrode 221. The body 220 formed between the first electrode 221 and the second electrode 222 may protrude outward from the first electrode 221 and the second electrode 222.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

A conductor having elasticity to contact the conductor of the electronic device;

A functional element connected to the elastic conductor and having a first electrode and a second electrode on at least a part of an upper surface and a lower surface, respectively; And

And a solder coupling the lower surface of the conductor having elasticity and the first electrode of the functional device,

Wherein at least one through hole is provided in a terminal portion of the conductor having elasticity opposite to the functional element,

And the solder includes a wedge portion which is inserted and fixed to the elastic conductor through the at least one through hole.
The method according to claim 1,

Wherein a portion of the wedge portion is formed to be larger than a diameter of the at least one through hole.
The method according to claim 1,

Wherein the conductor having elasticity is plated with a metal on one surface of the terminal portion facing the functional element, an inner wall of the at least one through hole, and a portion of the other surface of the terminal portion.
The method of claim 3,

And a portion of the upper surface of the terminal portion adjacent to the inner wall of the through hole is plated.
The method of claim 3,

Wherein the metal is Sn.
The method according to claim 1,

Wherein the plurality of through holes are provided symmetrically with respect to a center of the terminal portion.
The method according to claim 1,

Wherein the through-holes are formed in a plurality of points and are provided symmetrically with respect to a center of the terminal portion.
The method according to claim 1,

Wherein the plurality of through holes are provided at the center and both sides of the terminal portion.
The method according to claim 1,

Wherein the first electrode and the second electrode are provided on the upper surface and the lower surface of the functional device.
The method according to claim 1,

The conductor having elasticity may be formed,

A clip-shaped contact portion in contact with the conductor of the electronic device; And

And a bending portion having a predetermined curvature to impart an elastic force.
11. The method of claim 10,

Wherein the resilient conductor further comprises a sidewall extending vertically from the terminal portion at a long side.
12. The method of claim 11,

Wherein the sidewall extends at least a portion of the short side where the bend is not formed.
11. The method of claim 10,

And the bent portion extends from the terminal portion.
11. The method of claim 10,

Wherein the bent portion is spaced apart from the terminal portion by a predetermined distance.
The method according to claim 1,

Wherein the functional device has an electric shock prevention function for blocking a leakage current of an external power source flowing from a ground of a circuit board of the electronic device, a communication signal transfer function for passing a communication signal flowing into the conductive case or from the circuit board, And a function of at least one of an ESD protection function which is passed by discharging when an electrostatic charge is inputted from the case.