Dielectric laminated device and manufacturing method thereof

Details Dielectric laminated device and manufacturing method thereof Dielectric laminated device and manufacturing method thereof

2001-05-23

2003-02-11

Pascal, Robert (Department: 2817)

Wave transmission lines and networks

Coupling networks

Wave filters including long line elements

C333S134000, C333S219000

Reexamination Certificate

active

06518863

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric laminated device that is mainly used for high frequency radio equipment or the like such as a portable telephone.
2. Description of the Prior Art
Recently, as the communication equipment becomes miniaturized, the dielectric laminated device that is advantageous for the miniaturization is often used as a high frequency device. One example of the above described conventional dielectric laminated device will be described below while referring to the drawings.
FIG. 4
is a drawing showing an exploded illustration of a strip line conductor of a conventional dielectric laminated device that is formed by normal screen printing. In
FIG. 4
, reference numerals
101
a
,
101
b
,
101
c
,
101
d
,
101
e
denote dielectric layers, and reference numerals
102
a
,
102
b
denote shield conductors, and reference numerals
403
a
,
403
b
,
104
a
,
104
b
,
104
c
denote strip line conductors, and reference numerals
105
a
,
105
b
,
106
a
,
106
b
,
106
c
,
106
d
,
106
e
,
106
f
denote external conductors.
In the interior of the layered product composed of dielectric layers
101
a
to
101
e
, the shield conductor
102
a
, the strip line conductors
403
a
,
403
b
, the strip line conductors
104
a
,
104
b
,
104
c
, and the shield conductor
102
b
are arranged between the dielectric layers in turn, and furthermore, the external conductors
106
a
,
106
b
,
106
c
,
106
e
, and
106
f
in front and on the left and right sides of the layered product connect the shield conductors
102
a
,
102
b
and form the ground terminal, and the external conductor
106
d
on the rear of the layered product connects the common short-circuit ends of the shield conductors
102
a
,
102
b
and the strip line conductors
403
a
,
403
b
, and becomes the ground terminal, the external conductors
105
a
,
105
b
on the left and right sides of the layered product are connected to the strip line conductors
104
a
,
104
b
, respectively, and form the input and output terminals.
As for the dielectric laminated device composed as mentioned above, the function thereof will be described below.
The strip line conductors
403
a
,
403
b
compose a resonator of the quarter wavelength short-circuit type, and the strip line conductor
104
c
forms a capacitor by being arranged facing to part of the above described strip line conductors
403
a
,
403
b
, and connects the above described resonator of the quarter wavelength short-circuit type, and the strip line conductors
104
a
,
104
b
form a capacitor by being arranged facing to part of the above described strip line conductors
403
a
,
403
b
, respectively, and function as the input and output terminals by connecting one of the above described strip line conductors
104
a
,
104
b
and the external conductors
105
a
,
105
b
, respectively. Accordingly, the dielectric laminated device in
FIG. 4
functions as a band-pass filter in which the external conductors
105
a
,
105
b
are the input and output terminals.
BRIEF SUMMARY OF THE INVENTION
Object of the Invention
However, in such a construction as mentioned above, the edge angle of a side part of the strip line conductor becomes small, and the conductor loss because of the concentration of electric field to the side pointed part becomes large, and therefore, the loss as the filter characteristics also becomes large. “Edge angle becomes small” in the above description will be described by using FIG.
5
.
FIG. 5
is one end face view when the conventional dielectric laminated device shown in
FIG. 4
is cut by a plane substantially at right angles to the strip line conductors
403
a
,
403
b
that have substantially parallel relation. As shown in
FIG. 5
, the angle of the edge part
1403
of the strip line conductors
403
a
,
403
b
is small, and therefore, the concentration of electric field to that edge part
1403
is caused.
When the total of the strip line conductors
403
a
,
403
b
is made uniformly thick, and the angle of the edge part is made large in order to solve this problem, the stress applied to the interior of the laminated device at the time of dropping the temperature in the burning process or at the time of solder re-flow or the like becomes large by the difference in the heat expansion ratio between the metal to be the conductor and the dielectric layer. By this increased stress, a crack is caused in the laminated device, and as a result of that, there has been such a problem that the degradation of electric characteristics or the lowering of mechanical strength is caused.
Furthermore, there has been a deviation in the distribution of the current flowing in the strip line conductor
403
. That deviation in the distribution of the current will be described by using FIG.
10
.
FIG. 10
is a figure showing the distribution of the current flowing in the strip line conductor
403
a
in
FIG. 4
that composes the resonator of the quarter wavelength. As shown in
FIG. 10
, it is apparent that the distribution of the current is large on the short-circuit end side, and small on the open end side. By the way, the thickness of the conventional strip line conductor
403
a
has substantially been uniform, and therefore, in the strip line conductor
403
a
, the conductor loss on the short-circuit end side where current is concentrated is bigger than the conductor loss on the open end side. That is, it was equivalent to the resistance the short-circuit end side where current is concentrated is bigger than the resistance on the open end side. Therefore, there has been such a problem that the loss as the filter characteristics is also large. This problem has also been caused similarly in the strip line conductor
403
b.
Furthermore, a similar problem has also been caused in the strip line conductor composing the resonator of the half wavelength. In
FIG. 11
, the distribution of the current flowing in the strip line conductor composing the resonator of the half wavelength is shown. As shown in
FIG. 11
, it is apparent that a part where a lot of current flows exists in the central part in the case of the strip line conductor composing the resonator of the half wavelength. The thickness of the conventional strip line conductor has been substantially uniform, and therefore, in the strip line conductor composing the resonator of the half wavelength, the resistance value on the short-circuit end side at the central part has been larger than the resistance value on the open end side, and therefore, there has been such a problem that the loss as the filter characteristics is also large.
The present invention is achieved due to the above described problems, and it is an object thereof to provide a dielectric laminated device in which it is difficult to cause the concentration of electric field to be the source of the increase of the loss of the conductor.
Furthermore, it is an object of the present invention to provide a dielectric laminated device in which the resistance of the strip line conductor is more leveled than that of the prior art.
The 1st embodiment of the present invention is a dielectric laminated device, comprising:
a layered product including a plurality of dielectric layers; and
a plurality of strip line conductors arranged in the interior of the layered product,
wherein the thickness of at least part of the side part of at least one strip line conductor among said plurality of strip line conductors is thicker than that of the central part.
The 2nd embodiment of the present invention is the dielectric laminated device according to 1st embodiment, wherein said at least one strip line conductor forms a resonator of the quarter wavelength where the end is a short-circuit, and the thickness of the side part on the short-circuit end side of the resonator is thicker than that of the central part.
The 3rd embodiment of the present invention is the dielectric laminated device according to 1st embodiment, wherein said at least one strip line conductor forms a resonator of the half wavelength where th

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