U.S. patent application number 15/920915 was filed with the patent office on 2018-09-20 for attenuation reduction structure for flexible circuit board.
The applicant listed for this patent is ADVANCED FLEXIBLE CIRCUITS CO., LTD.. Invention is credited to CHIH-HENG CHUO, GWUN-JIN LIN, KUO-FU SU.
Application Number | 20180270947 15/920915 |
Document ID | / |
Family ID | 63491205 |
Filed Date | 2018-09-20 |
United States Patent
Application |
20180270947 |
Kind Code |
A1 |
SU; KUO-FU ; et al. |
September 20, 2018 |
ATTENUATION REDUCTION STRUCTURE FOR FLEXIBLE CIRCUIT BOARD
Abstract
A signal attenuation reduction structure for a flexible circuit
board includes at least one conductive paste coating zone formed on
surfaces of signal lines and an insulation layer formed on a
dielectric layer of the flexible circuit board such that the
conductive paste coating zone corresponds to at least one signal
line or covers a plurality of signal lines. An anisotropic
conductive film is formed on surfaces of the insulation layer and
the conductive paste coating zone of the flexible circuit board.
The anisotropic conductive film is pressed to bond between the
conductive paste coating zone and a shielding layer such that the
conductive paste coating zone and the shielding layer achieve
electrical connection therebetween in a vertical direction through
the anisotropic conductive film.
Inventors: |
SU; KUO-FU; (ZHONGLI CITY,
TW) ; CHUO; CHIH-HENG; (BADE CITY, TW) ; LIN;
GWUN-JIN; (TAOYUAN CITY, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ADVANCED FLEXIBLE CIRCUITS CO., LTD. |
ZHONGLI CITY |
|
TW |
|
|
Family ID: |
63491205 |
Appl. No.: |
15/920915 |
Filed: |
March 14, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15664031 |
Jul 31, 2017 |
9942984 |
|
|
15920915 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 2201/0715 20130101;
H05K 1/0218 20130101; H05K 1/0219 20130101; H05K 1/092 20130101;
H05K 2201/0723 20130101; H05K 1/0237 20130101; H05K 1/0393
20130101; H05K 1/0245 20130101 |
International
Class: |
H05K 1/02 20060101
H05K001/02; H05K 1/09 20060101 H05K001/09; H05K 1/03 20060101
H05K001/03 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2017 |
TW |
106109226 |
Claims
1. A flexible circuit board, comprising: a dielectric layer having
a top surface; at least one signal line disposed for high-frequency
applications, the at least one signal line being formed on the top
surface of the dielectric layer; an insulation layer formed on the
at least one signal line and the top surface of the dielectric
layer; at least one conductive paste coating zone formed on the
insulation layer and corresponding to the at least one signal line;
an anisotropic conductive film formed on the insulation layer and
the at least one conductive paste coating zone, made of different
material composition from the at least one conductive paste coating
zone and including an insulation resin material containing a
plurality of conductive particles therein; and a shielding layer
formed on the anisotropic conductive film to span contiguously over
the at least one signal line; wherein the at least one conductive
paste coating zone is disposed in embedded manner within the
anisotropic conductive film, regions of the anisotropic conductive
film thereby extending between the at least one conductive paste
coating zone and the shielding layer to establish an electrical
connection between the at least one conductive paste coating zone
and the shielding layer in a vertical direction therethrough.
2. The flexible circuit board as claimed in claim 1, wherein the at
least one conductive paste coating zone is formed of a conductive
paste selected from one of silver paste, copper paste, and aluminum
paste.
3. The flexible circuit board as claimed in claim 1, wherein the
shielding layer is formed of a material selected from one of
silver, copper, aluminum, and gold.
4. The flexible circuit board as claimed in claim 1, wherein the
dielectric layer includes at least one grounding line formed
thereon and the grounding line is electrically connected through a
conductive path to the shielding layer.
5. The flexible circuit board as claimed in claim 1, wherein the
anisotropic conductive film is pressed at a predetermined
temperature and a predetermined pressure to bond between the at
least one conductive paste coating zone and the shielding
layer.
6. A flexible circuit board, comprising: a dielectric layer having
a top surface; a plurality of signal lines adjacent to and
insulated from each other, formed on the top surface of the
dielectric layer, at least one of the plurality of signal lines
being disposed for high-frequency applications; an insulation layer
formed on the plurality of signal lines and the top surface of the
dielectric layer; an extended conductive paste coating zone formed
on the insulation layer and corresponding to the plurality of
signal lines; an anisotropic conductive film formed on the
insulation layer and the extended conductive paste coating zone,
made of different material composition from the extended conductive
paste coating zone and including an insulation resin material
containing a plurality of conductive particles therein; and a
shielding layer formed on the anisotropic conductive film to span
contiguously over the plurality of signal lines; wherein the
extended conductive paste coating zone is disposed in embedded
manner within the anisotropic conductive film, a region of the
anisotropic conductive film thereby extending between the extended
conductive paste coating zone and the shielding layer to establish
an electrical connection between the extended conductive paste
coating zone and the shielding layer in a vertical direction
therethrough.
7. The flexible circuit board as claimed in claim 6, wherein the
extended conductive paste coating zone is formed of a conductive
paste selected from one of silver paste, copper paste, and aluminum
paste.
8. The flexible circuit board as claimed in claim 6, wherein the
shielding layer is formed of a material selected from one of
silver, copper, aluminum, and gold.
9. The flexible circuit board as claimed in claim 6, wherein the
dielectric layer includes at least one grounding line formed
thereon and the grounding line is electrically connected through a
conductive path to the shielding layer.
10. The flexible circuit board as claimed in claim 6, wherein the
anisotropic conductive film is pressed at a predetermined
temperature and a predetermined pressure to bond between the
extended conductive paste coating zone and the shielding layer.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 15/664,031, filed on Jul. 31, 2017 and
currently pending, entitled "ATTENUATION REDUCTION STRUCTURE FOR
FLEXIBLE CIRCUIT BOARD." This application also claims foreign
priority to Taiwanese Patent Application No. 106109226, filed on
Mar. 17, 2017, a certified copy of which was previously filed with
application Ser. No. 15/664,031.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to a signal attenuation
shielding structure of a flexible circuit board, and in particular
to a signal attenuation reduction structure that is formed by
arranging a conductive paste coating zone in a flexible circuit
board to correspond to at least one high-frequency signal line and
an anisotropic conductive film arranged to provide electrical
connection in a vertical direction between the conductive paste
coating zone and a shielding layer.
2. The Related Arts
[0003] For all sorts of electronic devices that are contemporarily
available, the amount of data transmitting through signal lines is
getting larger and larger and thus, the number of signal
transmission lines required is increased and frequencies at which
signals are transmitting are also getting higher and higher.
[0004] A high frequency signal transmission technique is achieved
with two high frequency signal lines that are grouped as a signal
pair to respectively transmit signals having identical amplitude,
but at opposite phases so that the signal transmission lines are
provided with an improved effect of suppressing electromagnetic
interference.
[0005] Although such a high frequency transmission technique
greatly improves potential problems that might occur in the
transmission of signals, yet poor designs may often cause problems,
such as signal reflection, dispersion of electromagnetic wave, loss
of signal in transmission and receipt, and signal waveform
distortion, in actual applications.
[0006] To suppress problems concerning interference of
electromagnetic wave radiation and impedance match occurring in a
high frequency signal line of a flexible circuit board, it is
common to adopt a structure including a copper- or aluminum-based
shielding layer; however, the thickness involved is relatively
large and flexibility is poor. It is also common heretofore to form
such a shielding layer by coating a silver paste layer; however,
material cost is high and manufacturing processes are
complicated.
SUMMARY OF THE INVENTION
[0007] In view of the drawbacks of the prior art, an objective of
the present invention is to provide a high-frequency signal
attenuation reduction structure that is formed by combining a
conductive paste coating zone, anisotropic conductive film, and a
shielding layer together.
[0008] The technical solution that the present invention adopts to
achieve the above objective is that at least one conductive paste
coating zone is formed on a surface of high-frequency signal lines
and an insulation layer that are formed on a dielectric layer of a
flexible circuit board such that the conductive paste coating zone
corresponds to at least one high-frequency signal line or covers a
plurality of signal lines. An anisotropic conductive film is formed
on surfaces of the insulation layer and the conductive paste
coating zone of the flexible circuit board. The anisotropic
conductive film is pressed to bond between the conductive paste
coating zone and a shielding layer such that the conductive paste
coating zone and the shielding layer achieve electrical connection
therebetween in a vertical direction by means of the anisotropic
conductive film.
[0009] In the above solution, the conductive paste coating zone is
formed of a conductive paste selected from one of silver paste,
copper paste, and aluminum paste.
[0010] In the above solution, the shielding layer is formed of a
material selected from one of silver, copper, aluminum, and
gold.
[0011] In the above solution, the dielectric layer comprises at
least one grounding line formed thereon and the grounding line is
electrically connected through a conductive path to the shielding
layer
[0012] In the above solution, the anisotropic conductive film is
pressed at a predetermined temperature and a predetermined pressure
to bond between the conductive paste coating zone and the shielding
layer.
[0013] In the above solution, the plurality of pairs of
high-frequency signal lines comprise at least one pair of
differential-mode signal lines.
[0014] In another embodiment of the present invention, the
conductive paste coating zone is coated in an area that covers a
plurality of pairs of high-frequency signal lines.
[0015] The efficacy of the present invention is that, as compared
to the structure of the prior art copper- or aluminum-based
shielding layer, the present invention offers advantages including
having a smaller thickness and better flexibility and, as compared
to the prior art shielding layer that is formed by coating a layer
of silver paste, the present invention offers advantages of low
material cost and simplified manufacturing process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present invention will be apparent to those skilled in
the art by reading the following description of preferred
embodiments of the present invention, with reference to the
attached drawings, in which:
[0017] FIG. 1 is a cross-sectional diagram showing a first
embodiment of the present invention;
[0018] FIG. 2 is an enlarged view of a circle portion "A" of FIG.
1;
[0019] FIG. 3 is a cross-sectional diagram showing a second
embodiment of the present invention;
[0020] FIG. 4 is an enlarged view of a circle portion "B" of FIG.
3;
[0021] FIG. 5 is a cross-sectional diagram showing a third
embodiment of the present invention;
[0022] FIG. 6 is an enlarged view of a circle portion "C" of FIG.
5;
[0023] FIG. 7 is a cross-sectional diagram showing a fourth
embodiment of the present invention; and
[0024] FIG. 8 is an enlarged view of a circle portion "D" of FIG.
7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Referring collectively to FIGS. 1 and 2, FIG. 1 is a
cross-sectional diagram showing a first embodiment of the present
invention and FIG. 2 is an enlarged view of a circle portion "A" of
FIG. 1. As shown in the drawings, a flexible circuit board 100
comprises a dielectric layer 1 on which a plurality of pairs of
high-frequency signal lines 2a, 2b that are adjacent to and
insulated from each other are formed. An insulation layer 3 is
formed on the plurality of pairs of the high-frequency signal lines
2a, 2b and a top surface of the dielectric layer 1.
[0026] The insulation layer 3 of the flexible circuit board 100 has
a surface on which a plurality of conductive paste coating zones 4
are formed through coating and each of the conductive paste coating
zones 4 has a coating area that corresponds to one of the pairs of
high-frequency signal lines 2a, 2b. The conductive paste coating
zones 4 are formed of a conductive paste selected from one of
silver paste, copper paste, and aluminum paste.
[0027] An anisotropic conductive film 5 is formed on the surfaces
of the insulation layer 3 and the conductive paste coating zones 4
of the flexible circuit board 100. The anisotropic conductive film
5 is made of an insulation rein material 51 containing a plurality
of conductive particles 52 therein.
[0028] A shielding layer 6 is formed on the anisotropic conductive
film 5, so that the shielding layer 6 is set to cover, via the
anisotropic conductive film 5, the surface of the insulation layer
3 and the surface of the conductive paste coating zones 4 of the
flexible circuit board 100. The shielding layer 6 is formed of one
of silver, copper, aluminum, and gold. The anisotropic conductive
film 5 is pressed, at a predetermined temperature and a
predetermined pressure, to bond between the conductive paste
coating zones 4 and the shielding layer 6. The conductive paste
coating zones 4 and the shielding layer 6 achieve an electrical
connection therebetween in the vertical direction V (namely Z-axis
direction) by means of the conductive particles 52 of the
anisotropic conductive film 5.
[0029] The dielectric layer 1 comprises at least one grounding line
7 formed thereon and the grounding line 7 is electrically
connected, via a conductive path 61, to the shielding layer 6. The
dielectric layer 1 has an underside on which a conductive layer 8
is formed thereon, and then an insulation layer 9 is further formed
on the conductive layer 8.
[0030] The plurality of pairs of the high-frequency signal lines
2a, 2b comprise at least one pair of differential-mode signal lines
for transmission of differential-mode signals and may also comprise
a common-mode signal lines for transmission of common-mode
signals.
[0031] FIG. 3 is a cross-sectional diagram showing a second
embodiment of the present invention. FIG. 4 is an enlarged view of
a circle portion "B" of FIG. 3. The instant embodiment comprises
components/parts that are generally similar to those of the first
embodiment and similar components/parts are designated with the
same reference numerals for consistency. In the instant embodiment,
the flexible circuit board 100a similarly comprises a dielectric
layer 1, a plurality of pairs of high-frequency signal lines 2a, 2b
that are adjacent to and insulated from each other, an insulation
layer 3, an anisotropic conductive film 5, a shielding layer 6, a
grounding line 7, a conductive layer 8, and an insulation layer
9.
[0032] In the instant embodiment, a top surface of the insulation
layer 3 is coated and thus formed with an extended conductive paste
coating zone 4a, and the extended conductive paste coating zone 4a
has an extended coating area that correspondingly covers the
plurality of pairs of the high-frequency signal lines 2a, 2b. The
extended conductive paste coating zone 4a is formed of conductive
paste that comprises one of silver paste, copper paste, and
aluminum paste.
[0033] The shielding layer 6 is set to cover, via the anisotropic
conductive film 5, the surface of the insulation layer 3 and the
extended conductive paste coating zone 4a of the flexible circuit
board 100. The anisotropic conductive film 5 is pressed, at a
predetermined temperature and a predetermined pressure, to bond
between the extended conductive paste coating zone 4a and the
shielding layer 6. The extended conductive paste coating zone 4a
and the shielding layer 6 achieve an electrical connection
therebetween in the vertical direction V (namely Z-axis direction)
by means of conductive particles 52 of the anisotropic conductive
film 5.
[0034] FIG. 5 is a cross-sectional diagram showing a third
embodiment of the present invention. FIG. 6 is an enlarged view of
a circle portion "C" of FIG. 5. In the instant embodiment, the
flexible circuit board 100b comprises a dielectric layer 1 and at
least one signal line 2 formed on the top surface of the dielectric
layer 1. The signal line 2 is disposed for high-frequency
applications. For example, the signal line 2 may be used as a radio
frequency signal transmission line for antenna.
[0035] At least one conductive paste coating zone 4 is formed on
the insulation layer 3 and corresponding to the signal line 2. An
anisotropic conductive film 5 is formed on the insulation layer 3
and the conductive paste coating zone 4, made of different material
composition from the conductive paste coating zone 4 and including
an insulation resin material 51 containing a plurality of
conductive particles 52 therein, as shown in FIG. 6.
[0036] A shielding layer 6 is formed on the anisotropic conductive
film 5 and electrically connects to a grounding line 7 via a
conductive path 61. The conductive paste coating zones 4 and the
shielding layer 6 achieve an electrical connection therebetween in
the vertical direction V (namely Z-axis direction) by means of the
conductive particles 52 of the anisotropic conductive film 5.
[0037] FIG. 7 is a cross-sectional diagram showing a fourth
embodiment of the present invention. FIG. 8 is an enlarged view of
a circle portion "D" of FIG. 7. In the instant embodiment, the
flexible circuit board 100c comprises a dielectric layer 1 and a
plurality of signal lines 2 formed on the top surface of the
dielectric layer 1. At least one of the signal lines 2 is disposed
for high-frequency applications. For example, the at least one
signal line 2 may be used as a radio frequency signal transmission
line for antenna.
[0038] An extended conductive paste coating zone 4a is formed on
the insulation layer 3 and has an extended coating area that
correspondingly covers the plurality of signal lines 2. An
anisotropic conductive film 5 is formed on the insulation layer 3
and the extended conductive paste coating zone 4a, made of
different material composition from the extended conductive paste
coating zone 4a and including an insulation resin material 51
containing a plurality of conductive particles 52 therein, as shown
in FIG. 8.
[0039] A shielding layer 6 is formed on the anisotropic conductive
film 5 and electrically connects to a grounding line 7 via a
conductive path 61. The extended conductive paste coating zones 4a
and the shielding layer 6 achieve an electrical connection
therebetween in the vertical direction V (namely Z-axis direction)
by means of the conductive particles 52 of the anisotropic
conductive film 5.
[0040] Although the present invention has been described with
reference to the preferred embodiments thereof, it is apparent to
those skilled in the art that a variety of modifications and
changes may be made without departing from the scope of the present
invention which is intended to be defined by the appended
claims.
* * * * *