Monolithic electronic device

Details Monolithic electronic device Monolithic electronic device

2002-10-01

2004-03-30

Pascal, Robert (Department: 2817)

Wave transmission lines and networks

Coupling networks

Frequency domain filters utilizing only lumped parameters

C333S185000

Reexamination Certificate

active

06714100

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a monolithic electronic device. More particularly, the present invention relates to a monolithic electronic device included in an RF electric circuit.
2. Description of the Related Art
A monolithic LC filter
1
shown in
FIG. 7
is a typical monolithic electronic device. The monolithic LC filter
1
includes two LC bandpass filters. The monolithic LC filter
1
includes a first insulation sheet
2
, a shield electrode
11
on a second insulation sheet
2
, capacitor electrodes
8
b
and
9
b
on a third insulation sheet
2
, inductor electrodes
4
b
and
5
b
on a fourth insulation sheet
2
, a coupling capacitor electrode
12
on a fifth insulation sheet
2
, inductor electrodes
4
a
and
5
a
on a sixth insulation sheet
2
, capacitor electrodes
8
a
and
9
a
on a seventh insulation sheet
2
, and a shield electrode
10
on an eighth insulation sheet
2
.
One end of each of the inductor electrodes
4
b
and
5
b
is exposed at the front of the fourth insulation sheet
2
. The widths of the other ends, which are indicated by reference numerals
6
b
and
7
b
, are larger than those of the inductor electrodes
4
b
and
5
b
. The other ends
6
b
and
7
b
function as capacitor electrodes. An input lead electrode
14
b
extends from the middle of the inductor electrode
4
b
and is exposed at the left side of the fourth insulation sheet
2
. Further, an input lead electrode
15
b
extends from the middle of the inductor electrode
5
b
and is exposed at the right side of the fourth insulation sheet
2
.
One end of each of the inductor electrodes
4
a
and
5
a
is exposed at the front of the sixth insulation sheet
2
. The widths of the other ends, which are indicated by reference numerals
6
a
and
7
a
, are larger than those of the inductor electrodes
4
a
and
5
a
. The other ends
6
a
and
7
a
function as capacitor electrodes. An input lead electrode
14
a
extends from the middle of the inductor electrode
4
a
and is exposed at the left side of the sixth insulation sheet
2
. Further, an input lead electrode
15
a
extends from the middle of the inductor electrode
5
a
and is exposed at the right side of the sixth insulation sheet
2
.
One end of each of the capacitor electrodes
8
a
and
8
b
is exposed at the back of the seventh insulation sheet
2
and the third insulation sheet
2
. The capacitor electrode
8
a
is opposed to the other end
6
a
of the inductor electrode
4
a
and the capacitor electrode
8
b
is opposed to the other end
6
b
of the inductor electrode
4
b
, whereby a capacitor C
1
is provided. Further, the inductor electrodes
4
a
and
4
b
define a dual inductor L
1
. The capacitor C
1
and the dual inductor L
1
define an LC parallel resonant circuit. Thus, a first LC resonator Q
1
is provided.
One end of each of the capacitor electrodes
9
a
and
9
b
is exposed at the back of the seventh insulation sheet
2
and the third insulation sheet
2
. The capacitor electrode
9
a
is opposed to the other end
7
a
of the inductor electrode
5
a
and the capacitor electrode
9
b
is opposed to the other end
7
b
of the inductor electrode
5
b
, whereby a capacitor C
2
is provided. Further, the inductor electrodes
5
a
and
5
b
define a dual inductor L
2
. The capacitor C
2
and the dual inductor L
2
define an LC parallel resonant circuit. Thus, a second LC resonator Q
2
is provided.
The coupling capacitor electrode
12
is opposed to the other ends
6
a
,
6
b
,
7
a
, and
7
b
to define a coupling capacitor Cs
1
(not shown).
The shield electrode
10
, which has a large area, has extensions
10
a
,
10
b
,
10
c
,
10
d
,
10
e
,
10
f
,
10
g
,
10
h
,
10
i
, and
10
j
. The extensions
10
a
to
10
j
are exposed at the four sides of the eighth shield electrode
2
.
The shield electrode
11
, which has a large area, has extensions
11
a
,
11
b
,
11
c
,
11
d
,
11
e
,
11
f
,
11
g
,
11
h
,
11
i
, and
11
j
. The extensions
11
a
to
11
j
are exposed at the four sides of the second shield electrode
2
.
The first to eighth insulation sheets
2
are laminated in the order shown in FIG.
7
. Then, the laminated insulation sheets
2
are integrally fired and formed into a composite
15
shown in FIG.
8
. Further, as shown in
FIG. 9
, a conductive paste is applied to the front and the back of the composite
15
by a dipping method. Then, the conductive paste is fired, whereby side surface ground external electrodes
18
and
19
are formed. At that time, bent portions
18
a
and
19
a
of the side surface ground external electrodes
18
and
19
are formed on the top surface, the bottom surface, the left surface, and the right surface of the composite
15
. One end of each of the inductor electrodes
4
a
to
5
b
, the extensions
10
a
to
10
c
of the shield electrode
10
, and the extensions
11
a
to
11
c
of the shield electrode
11
are connected to the side surface ground external electrode
18
. One end of each of the capacitor electrodes
8
a
to
9
b
, the extensions
10
f
to
10
h
of the shield electrode
10
, and the extensions
11
f
to
11
h
of the shield electrode
11
are connected to the side surface ground external electrode
19
.
Then, as shown in
FIG. 10
, a conductive paste is applied to both sides of the composite
15
by a transfer printing method and fired. Subsequently, an input external electrode
16
, an output external electrode
17
, and end surface ground external electrodes
20
,
21
,
22
, and
23
are formed. At that time, bent portions
16
a
,
17
a
,
20
a
,
21
a
,
22
a
, and
23
a
are formed on the top surface and the bottom surface of the composite
15
. The end surface ground external electrodes
20
and
21
are electrically connected to the side surface ground external electrode
18
. The end surface ground external electrodes
22
and
23
are electrically connected to the side surface ground external electrode
19
. The input lead electrodes
14
a
and
14
b
are connected to the input external electrode
16
. The output lead electrodes
15
a
and
15
b
are connected to the output external electrode
17
.
The bent portions
16
a
to
23
a
have an influence on the characteristics of the LC filter
1
because, for example, they overlap the inductor electrodes
4
a
,
4
b
,
5
a
, and
5
b
, and so forth. Subsequently, a variation in the dimensions of the bent portions
16
a
to
23
a
causes the electrical characteristics of the LC filter
1
to vary. However, in the case of the known LC filter
1
, the bent portions
16
a
to
23
a
and the external electrodes
16
to
23
are formed at the same time. In such a case, it becomes difficult to reliably form the bent portions
16
a
to
23
a
. Therefore, the variation in the dimensions of the bent portions
16
a
to
23
a
becomes large. Accordingly, the electrical characteristics of the LC filter
1
tend to vary greatly.
The adhesion strength of the insulation sheets and the electrodes of the monolithic electronic device is low. Therefore, when the shield electrodes
10
and
11
, which each have a large area, are laminated, an opening is formed between each of the extensions
10
a
to
10
j
and
11
a
to
11
j
. The openings are formed in order to prevent delamination of the composite
15
. That is to say, the areas of the shield electrodes
10
and
11
, which are in contact with the insulation sheets
2
, are reduced, since delamination tends to occur with relative ease at the edge portions of the insulation sheets
2
. However, the areas of the insulation sheets which are in contact with each other are increased. In particular, large openings are formed between the extensions
10
j
and
10
a
of the shield electrode
10
and between the extensions
11
j
and
11
a
of the shield electrode
11
, and so forth because delamination tends to occur there due to internal stresses that tend to be exerted on the corners of the composite
15
.
When such openings are formed, however, electric fields and magnetic fields leak through the opening

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