U.S. patent application number 14/463320 was filed with the patent office on 2016-01-21 for emi gasket for shielding electromagnetic wave.
The applicant listed for this patent is ICH CO., LTD.. Invention is credited to YOUNG HUN KIM.
Application Number | 20160021798 14/463320 |
Document ID | / |
Family ID | 53886324 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160021798 |
Kind Code |
A1 |
KIM; YOUNG HUN |
January 21, 2016 |
EMI GASKET FOR SHIELDING ELECTROMAGNETIC WAVE
Abstract
The present invention provides a gasket formed by applying an
adhesive on four sides of an elastic body of a closed cell
polyurethane material, wrapping a copper film around the elastic
body other than a bottom bonding surface, forming a coating layer
by depositing or plating nickel on a surface exposing the copper
film, forming a resin coating layer on the nickel coating layer,
and applying a conductive adhesive on the bottom surface. The
present invention may drastically decrease thickness of the gasket
by using closed cell polyurethane instead of conventional open cell
polyurethane and may completely prevent oxidation and corrosion of
copper by depositing or plating nickel on the exposed portions of
the copper film and coating resin thereon. Furthermore, since a
fiber material is not used, conductive powders are not generated,
and thus short circuits or malfunctions can be reduced.
Inventors: |
KIM; YOUNG HUN; (Gunpo-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ICH CO., LTD. |
Gunpo-si |
|
KR |
|
|
Family ID: |
53886324 |
Appl. No.: |
14/463320 |
Filed: |
August 19, 2014 |
Current U.S.
Class: |
174/358 ;
156/185 |
Current CPC
Class: |
B32B 37/1284 20130101;
B32B 2457/00 20130101; B32B 2037/243 20130101; H05K 9/0015
20130101; B32B 2307/212 20130101 |
International
Class: |
H05K 9/00 20060101
H05K009/00; B32B 37/24 20060101 B32B037/24; B32B 37/12 20060101
B32B037/12; B32B 37/14 20060101 B32B037/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2014 |
KR |
10-2014-0091109 |
Claims
1. A gasket for shielding electromagnetic waves, the gasket formed
by applying an adhesive on four sides of an elastic body of a
closed cell polyurethane material, wrapping a copper film around
the elastic body other than a bottom bonding surface, forming a
nickel coating layer by depositing or plating nickel on a top
surface and a side surface where the copper film is exposed,
forming a resin coating layer on the nickel coating layer, and
applying a conductive adhesive on the bottom surface.
2. The gasket according to claim 1, wherein the copper film is
formed by plating or depositing copper on a polyester film.
3. The gasket according to claim 1, wherein resin of the resin
coating layer is fluoride resin or silicon resin.
4. The gasket according to claim 3, wherein the resin coating layer
is formed to have a thickness less than one micro meter.
5. The gasket according to claim 1, wherein a conductive non-woven
fabric layer is formed between the conductive adhesive and the
adhesive.
6. The gasket according to claim 5, wherein the conductive
non-woven fabric layer is formed by coating conductive metal on a
non-woven fabric.
7. The gasket according to claim 6, wherein the conductive metal is
nickel, cobalt or a mixture of these.
8. The gasket according to claim 2, wherein resin of the resin
coating layer is fluoride resin or silicon resin.
9. The gasket according to claim 2, wherein a conductive non-woven
fabric layer is formed between the conductive adhesive and the
adhesive.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims priority from Korean
Patent Application No. 10-2014-0091109 filed on Jul. 18, 2014 in
the Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an EMI gasket for shielding
electromagnetic waves, and more particularly, to an EMI gasket for
shielding electromagnetic waves, which has excellent
electromagnetic wave shielding performance.
[0004] 2. Background of the Related Art
[0005] Generally, electromagnetic waves generated by internal
circuits of various kinds of electronic devices are radiated to
outside through the air or conducted through a power line or the
like.
[0006] Such electromagnetic waves are known to generate noises and
malfunctions in the components or devices in the neighborhood and
have a bad effect on human bodies.
[0007] As electronic devices are becoming thinner and their
circuits are getting complicated recently, possibility of
generating electromagnetic waves abruptly increases, and
regulations on the electromagnetic waves are strengthened in Korea
as well as in developed countries.
[0008] Accordingly, conductive sponges are used conventionally so
that the electromagnetic waves generated by the circuits of the
electronic devices may not be radiated to outside.
[0009] However, the conductive sponge is disadvantageous in that
since conductive powders are generated, a module risk factor may
occur, and its restoring force is low.
[0010] In addition, Korean Utility Model Registration No.
20-0208434 discloses a gasket formed by wrapping a copper plate of
high conductivity on three sides of an electric conductor, in a
general gasket in which four sides of a rectangular elastic body of
a polyurethane material are wrapped by a conductor of a PE fiber
coated with copper and nickel, and an adhesive tape is attached on
the bottom side.
[0011] However, since a conductive fabric of a coated fiber is also
used in this case and generates conductive powders, a short circuit
or a malfunction is worried, and corrosion is also worried since a
copper plate is used.
SUMMARY OF THE INVENTION
[0012] Accordingly, the present invention has been made in view of
the above-mentioned problems occurring in the prior art, and it is
an object of the present invention to provide an EMI gasket for
shielding electromagnetic waves, which has excellent
electromagnetic wave shielding performance without generating a
short circuit or a malfunction.
[0013] To accomplish the above object, according to the present
invention, there is provided an EMI gasket for shielding
electromagnetic waves, the EMI gasket formed by applying an
adhesive on four sides of an elastic body of a closed cell
polyurethane material, wrapping a copper film around the elastic
body other than a bottom bonding surface, forming a coating layer
on the copper film by depositing or plating nickel, and applying a
conductive adhesive on the bottom surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and other objects, features and advantages of the
present invention will be apparent from the following detailed
description of the preferred embodiments of the invention in
conjunction with the accompanying drawings, in which:
[0015] FIG. 1 is a view showing a cross section of a gasket of the
present invention;
[0016] FIG. 2 is a view showing a layered structure of the center
portion of a gasket of the present invention;
[0017] FIG. 3 is a side cross-sectional view showing a layered
structure of the side surface of a gasket of the present
invention;
[0018] FIG. 4 is a picture showing gaskets of the present invention
respectively designed and applied to be appropriate to the shape of
a component;
[0019] FIG. 5 is a view showing a result of a salt water spray test
performed on an embodiment of the present invention and a
comparative example; and
[0020] FIG. 6a is a picture or photographic view showing a result
of a salt water spray test performed on test samples of an
embodiment of the present invention, while FIG. 6b is a picture or
photographic view showing comparative examples.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] FIG. 1 is a view showing a cross section of a gasket of the
present invention, FIG. 2 is a view showing a layered structure of
the center portion of a gasket of the present invention, and FIG. 3
is a side cross-sectional view showing a layered structure of the
side surface of a gasket of the present invention. The base layer
10 in the middle uses a closed cell polyurethane material. The base
layer has a thickness of 150 to 250 micrometers. Since a closed
cell polyurethane material is used, the entire thickness of the
currently and commonly used gasket having a thickness of around 400
to 500 micrometers can be reduced by half. An adhesive layer 20 is
applied on four sides including side surfaces and top and bottom
surfaces. Thickness of the adhesive layer is generally around 10
micrometers. As shown in FIG. 1, a copper film 30 is attached on
all areas other than the center portion of the bottom side which is
attached to the apparatus. The copper film is manufactured by
laminating a thin film copper plate on a polyester film or by
plating or depositing copper on the polyester film. The copper film
is formed to have a thickness of less than 10 micrometers,
preferably less than 5 micrometers, further preferably less than 3
micrometers, and most preferably 2 micrometers. In order to prevent
corrosion of the copper layer, it is preferable to form a nickel
layer 40 by coating, depositing or sputtering nickel on all sides
other than the bottom surface which is attached to the apparatus.
The nickel layer is formed to have a thickness of less than one
micrometer, preferably less than 0.5 micrometers, and most
preferably 0.3 micrometers.
[0022] In addition, an extremely thin resin coating layer 60 is
formed to completely prevent corrosion of the copper layer. The
resin coating layer is formed to have a thickness less than one
micrometer so as not to interfere conductivity. Corrosion of the
copper layer can be completely prevented by forming the coating
layer. The coating layer is preferably formed using silicon or
fluorideresin.
[0023] A conductive adhesive layer 50 is formed on the bottom
surface which is attached to the apparatus. In order to improve
adhesiveness, a conductive non-woven fabric layer 30' may be
further formed on the top of the conductive adhesive layer. A
conductive material such as nickel, cobalt or the like is coated on
the top of the conductive non-woven fabric layer. Damages caused by
a short circuit or a malfunction can be reduced compared with a
conventional technique using a fabric.
[0024] FIG. 4 shows a picture of gasket products of the present
invention. The gasket can be freely cut into a shape appropriate to
the usage of the product when it is actually used.
Embodiment 1
[0025] An adhesive is applied as thick as 10 micrometers on three
sides of closed cell polyurethane foam having a thickness of 150
micrometers, and a copper film of 2 micrometers is bonded in the
shape as shown in FIG. 1. A gasket having a total thickness of
about 200 micrometers is manufactured by applying a nickel coating
of 3 micrometers and a fluorideresin coating of 0.5 micrometers on
the top and side surfaces and applying a conductive adhesive on the
bottom surface as thick as 30 micrometers.
[0026] Properties of the product shown in embodiment 1 of the
present invention are compared with those of a conventional
conductive sponge (comparative example 1), and a result thereof is
shown in Table 1. A Toray KP film product is used as the conductive
sponge. A restoring force test is performed to measure a restoring
force after compressing a test sample by 50%, and the test is
performed on a test sample having a size of 25 mm.times.25 mm at a
temperature of 85.degree. C. for 24 hours.
TABLE-US-00001 TABLE 1 Comparative Embodiment 1 example 1
Conductive powder None Generated Restoring force 97% 10% Minimum
thickness 200 400 Surface resistance 0.03/ 0.1/
[0027] As is understood from the result shown in Table 1, the
product of the present invention does not have a module risk factor
since conductive powders are not generated, has a superior sealing
force as a gasket since its restoring force is excellent, and is
manufactured to be thin, and thus it may contribute to making a
thinner and lighter electronic device such as a cellular phone or
the like. In addition, since surface resistance is low,
electromagnetic wave shielding capability and conductivity of the
product of the present invention are superior.
Embodiments 2 to 4
[0028] In addition, gaskets are manufactured in the same manner as
shown in embodiment 1 while changing thickness of the closed cell
polyurethane foam to 200 micrometers, 250 micrometers and 300
micrometers, and restoring forces are measured by applying a load
of 400 g at a temperature of 70.degree. for 18 hours.
TABLE-US-00002 TABLE 2 Proper compression Total Foam rate (based
Compressed Restored thickness thickness on total thickness
thickness Restor- (T) (T) thickness) (T) (T) ing rate 0.20 0.15 25%
0.050 0.046 30% 0.25 0.20 24% 0.060 0.054 28% 0.30 0.25 33% 0.100
0.093 46% 0.35 0.30 34% 0.120 0.111 48% 0.40 0.35 40% 0.160 0.150
62%
TEST EXAMPLE 1
[0029] A salt water spray test has been conducted on the product of
embodiment 1 of the present invention and the products of
comparative example 1 and Korean Utility Model Registration No.
20-0208434 (comparative example 2). The test has been conducted
using 5% salt water at a temperature of 35.degree. C. for 24 hours.
The product of the embodiment of the present invention does not
show any change in appearance after the test, and the surface
resistance has not been changed since there is no corrosion.
Appearances of both the products of comparative example 1 and
comparative example 2 are changed due to corrosion, and values of
the surface resistance have been considerably increased after the
test.
TEST EXAMPLE 2
[0030] One half of a sheet is fabricated to be the same as the
product of embodiment 3 of the present invention, and the other
half is fabricated to be the same as embodiment 3 without a
fluorideresin coating process (comparative example 3), and degrees
of corrosion are compared after spraying ten liters of 5% salt
water at 35.degree. C. for 48 hours. Pictures compared are shown in
FIG. 5.
[0031] In addition, pictures of gaskets manufactured as test
samples and gone through the salt water spray test are shown in
FIG. 6. FIG. 6a shows a picture of products manufactured in
embodiment 3, and FIG. 6b shows a picture of products of
comparative example 3 respectively manufactured as a test sample
and gone through a salt water spray test. It is understood that
corrosion preventing performance is remarkably improved by the
fluorideresin coating of the present invention.
[0032] Furthermore, it is confirmed that the product of the
embodiment of the present invention does not show a change in the
surface resistance after the salt water is sprayed.
[0033] The present invention may drastically decrease thickness of
a gasket by using closed cell polyurethane instead of conventional
open cell polyurethane.
[0034] In addition, oxidation and corrosion of copper can be
prevented by depositing or plating nickel on three exposed portions
of a copper film.
[0035] Furthermore, since a fiber material is not used, conductive
powders are not generated, and thus short circuits or malfunctions
can be reduced.
[0036] The product of the present invention can be advantageously
used to shield electromagnetic waves of an electronic device such
as a cellular phone or the like. Compared with a conventional
product, since the product of the present invention does not
generate conductive powders, has a superior sealing force and is
manufactured to be thin, it may contribute to making a thinner and
lighter electronic device such as a cellular phone or the like. In
addition, since surface resistance of the product of the present
invention is low, its electromagnetic wave shielding capability and
conductivity are superior.
[0037] While the present invention has been described with
reference to the particular illustrative embodiments, it is not to
be restricted by the embodiments but only by the appended claims.
It is to be appreciated that those skilled in the art can change or
modify the embodiments without departing from the scope and spirit
of the present invention.
* * * * *