Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2001-02-16
2003-01-21
Paladini, Albert W. (Department: 2827)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S255000, C174S260000, C361S795000
Reexamination Certificate
active
06509531
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to monolithic ceramic electronic components, methods for manufacturing the same, and electronic devices including the monolithic ceramic electronic components. More particularly, the present invention relates to an improvement in the structure of terminals of monolithic ceramic electronic components.
2. Description of the Related Art
A conventional type of monolithic ceramic electronic component, which relates to the present invention, is known as a “monolithic ceramic substrate”. The monolithic ceramic electronic component includes a composite body having a multilayered structure including a plurality of ceramic layers.
Inside the composite body, interconnecting conductors are provided to constitute a desired circuit by using passive elements such as capacitors and inductors. Outside the composite body, an active element such as a conductor IC chip and a portion of a passive element as required are mounted.
The resulting monolithic ceramic electronic component is mounted on a desired interconnection substrate and constitutes a desired electronic device.
The monolithic ceramic electronic component is used as an LCR composite high-frequency component for use in mobile communication terminal devices, and as a composite component combining an active element such as a semiconductor IC chip and a passive element such as a capacitor, an inductor, and a resistor, or simply as a semiconductor IC package for use in computers.
More particularly, the monolithic ceramic electronic component is widely used to constitute various kinds of electronic components such as module substrates, RF diode switches, filters, chip antennas, various package components, composite devices, etc.
FIG. 9
is a sectional view illustrating a conventional monolithic ceramic electronic component. A monolithic ceramic electronic component
1
shown in
FIG. 9
includes a composite body
3
including a plurality of stacked ceramic layers
2
. The composite body
3
is provided with interconnecting conductors each of which is located in association with a particular ceramic layer
2
.
The interconnecting conductors are several first terminals
5
arranged on a first end surface
4
in the stacking direction of the composite body
3
, several second terminals
7
arranged on a second end surface
6
opposite to the first end surface
4
of the composite body
3
, several internal conductor layers
8
disposed at a particular interface between the ceramic layers
2
, and several via-hole conductors
9
penetrating a specific ceramic layer
2
.
The first terminal
5
is used for forming a connection with an interconnection substrate (not shown). In order to improve the bonding strength with the interconnection substrate, the first terminal
5
includes a conductor layer defined by a conductive paste that is applied by printing.
The second terminal
7
is used for forming a connection with a mounted component (not shown). In order to improve the bonding strength with the mounted component, as in the first terminal
5
, the second terminal
7
includes a conductor layer defined by a conductive paste that is applied by printing.
FIGS. 10A
to
10
E show, in sequence, part of a typical method for manufacturing the monolithic ceramic electronic component
1
shown in FIG.
9
. As shown in
FIG. 10A
, a ceramic green sheet
11
, which will form the ceramic layer
2
, is formed on a carrier film
10
of polyethylene terephthalate having a thickness of 50 &mgr;m to 100 &mgr;m. In this way, a composite sheet
12
in which the ceramic green sheet
11
is supported by the backing carrier film
10
is obtained.
During the subsequent steps, prior to a stacking step of the ceramic green sheet
11
, the ceramic green sheet
11
is handled in the form of the composite sheet
12
.
The reason for working the ceramic green sheet
11
with the carrier film
10
functioning as an undercoat is that the ceramic green sheet
11
has significantly low strength, is soft, and is breakable, and it is extremely difficult to handle the ceramic green sheet
11
by itself. The ceramic green sheet
11
in the form of the composite sheet
12
is easy to handle and to align during the process. Also, undesirable shrinking and undulation of the ceramic green sheet
11
can be prevented during the subsequent step of drying the conductive paste.
Next, as shown in
FIG. 10B
, several through holes
13
for forming the via-hole conductors
9
are formed in the composite sheet
12
. Alternatively, the through holes
13
may be formed so as not to penetrate the carrier film
10
and may be formed only in the ceramic green sheet
11
.
Next, as shown in
FIG. 10C
, by filling the through hole
13
with a conductive paste, a conductive paste section
14
which will be the via-hole conductor
9
is formed. At the same time, the conductive paste layer
15
, which will be the internal conductor layer
8
or a second terminal
7
, is formed by applying a conductive paste on the outer main surface of the ceramic green sheet
11
. Subsequently, the conductive paste section
14
and the conductive paste layer
15
are dried.
Next, as shown in
FIG. 10D
, after the carrier film
10
is separated from the ceramic green sheet
11
, a plurality of ceramic green sheets
11
are stacked so as to define a green composite body
16
which is the composite body
3
before firing.
The separation of the carrier film
10
may be performed prior to the stacking of the ceramic green sheet
11
as in the above description. The arrangement may be such that the ceramic green sheet
11
is stacked in the form of the composite sheet
12
, having the surface provided with carrier film
10
facing upward, and the carrier film
10
is separated every time one of the ceramic green sheets
11
is stacked.
Next, as shown in
FIG. 10E
, a conductive paste layer
17
, which will be the first terminal
5
, is formed by applying a conductive paste on one end surface of the green composite
16
by printing. The conductive paste layer
17
is then dried.
It should be noted that the conductive paste layer
17
, formed after the green composite
16
is obtained, may be used for the second terminal
7
and not for the first terminal
5
. In such a case, the conductive paste layer for the first terminal
5
is provided by the conductive paste layer
15
formed by the step shown in FIG.
10
C.
Next, the green composite
16
in the state shown in FIG.
10
E is pressed in the stacking direction and is fired. Thus, the monolithic ceramic electronic component
1
shown in
FIG. 9
is obtained.
The first terminal
5
and the second terminal
7
are plated with nickel and are then further plated with gold, tin, or solder, as required.
Although not shown in the drawings, the monolithic ceramic electronic component
1
is mounted on an interconnection substrate arranged to oppose the first end surface
4
so as to electrically connect via the conductive layer that constitutes the first terminal
5
. A component is mounted on the second end surface
6
and is electrically connected with the conductive layer that constitutes the second terminal
7
, but this is also not shown.
According to the manufacturing method of the monolithic ceramic electronic component
1
shown in
FIG. 10
, a step for applying the conductive paste by printing and a step for drying the same must be performed once again subsequent to obtaining the green composite body
16
in order to form the conductive paste layer
17
shown in FIG.
10
E. Thus, there is a problem of reduced production efficiency due to these extra printing and drying steps.
It is also possible to use another process in which the conductive paste layer
17
is applied by printing, is dried, and is fired after firing the green composite body
16
in the state shown in FIG.
10
D. In this case also, there is a problem of reduced production efficiency as in the above.
Since a screen printing technique is generally used in applying the conductive paste layer
17
, reliability of the s
Isebo Kazuhiro
Kato Isao
Sakai Norio
Alcalá José H.
Keating & Bennett LLP
Murata Manufacturing Co. Ltd
Paladini Albert W.
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