Electronic component

Details Electronic component Electronic component

2001-10-05

2004-10-19

Budd, Mark (Department: 2834)

Electrical generator or motor structure

Non-dynamoelectric

Piezoelectric elements and devices

C310S365000, C310S328000, C310S320000

Reexamination Certificate

active

06806626

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic component such as a piezoelectric resonator, and more particularly, to an electronic component in which an inner electrode for connection to electrodes provided on a pair of surfaces of the electronic component is provided in a member of the electronic component such as a piezoelectric member.
2. Description of the Related Art
Conventionally, in the production of oscillators and other similar devices, piezoelectric resonators utilizing a thickness shear vibration mode have often been used. In energy-trap type piezoelectric resonators utilizing a thickness shear vibration mode, resonance electrodes are provided on both main surfaces of an elongated rectangular piezoelectric plate. In such piezoelectric resonators, a resonance electrode provided on one main surface thereof is electrically connected to a connecting electrode which extends over an end surface of the piezoelectric plate, reaching the bottom surface so that surface-mounting is easily performed via one of the main surfaces. In some cases, the corners of the connecting electrode are scraped when the piezoelectric resonator is processed. Japanese Unexamined Patent Application Publication No. 8-237066 discloses a piezoelectric resonator, which is shown in the perspective view of
FIG. 15
, which improves the reliability of connecting electrodes provided on the front and back surfaces.
In a piezoelectric resonator
101
, resonance electrodes
103
and
104
are arranged so as to oppose each other at the center of an elongated piezoelectric plate
102
disposed therebetween.
Moreover, end-surface electrodes
105
and
106
are provided on the end surfaces
102
a
and
102
b
of the piezoelectric plate
102
, respectively. The end-surface electrodes
105
and
106
are electrically connected to the resonance electrodes
103
and
104
, respectively. Moreover, protective films
107
and
108
are arranged to cover and protect the end-surface electrodes
105
and
106
, respectively. The resonance electrodes
103
and
104
are arranged on the main surfaces of the piezoelectric plate
102
to extend over the protective films
107
and
108
, respectively.
Connecting electrodes
109
and
110
are provided on the upper and lower surfaces of the piezoelectric plate
102
, and are electrically connected to the end-surface electrodes
106
and
105
, respectively. Moreover, as shown in
FIG. 15
, the connecting electrodes
109
and
110
are provided on the upper and lower surfaces of the piezoelectric plate
102
and also on the upper and lower surfaces of the protective films
107
and
108
, respectively.
In the piezoelectric resonator
101
, the protective films
107
and
108
cover the end-surface electrodes
105
and
106
, respectively. This improves the reliability of the electrical connection between the resonance electrode
103
and the connecting electrode
110
and between the resonance electrode
104
and the connecting electrode
109
.
Referring to the manufacture of the piezoelectric resonator
101
, electrodes (referred to as completely coated electrodes), which will be formed to define the end-surface electrodes, are disposed on the entire areas of the main surfaces of a piezoelectric block
111
shown in
FIG. 16
, and the piezoelectric block
111
is polarized in the thickness direction. After the polarization, protective films
112
and
113
are provided on the completely coated electrodes (not shown), respectively. The first mother piezoelectric block
111
manufactured as described above is cut along the dashed lines A in FIG.
16
. Thus, the second mother piezoelectric block
114
shown in
FIG. 17
is obtained. After this, a mother resonance electrode
115
and a mother connecting electrode
116
, are provided on the piezoelectric block
114
. Subsequently, the piezoelectric block
114
is cut along the dashed lines B to obtain the piezoelectric resonator
101
.
In an energy-trap type piezoelectric resonator utilizing a thickness shear vibration mode, undesirable spurious responses are produced, depending on the size in the longitudinal direction of the piezoelectric plate
102
. These undesirable spurious responses increase when the size of the piezoelectric resonator is reduced. The length of the piezoelectric plate
102
must be adjusted so that spurious responses, which are due to the length of the piezoelectric plate
102
, are suppressed.
The size in the longitudinal direction of the piezoelectric resonator
101
is determined primarily by the thickness of the piezoelectric block
111
as seen in the above-described method of producing the piezoelectric resonator
101
. Accordingly, when the longitudinal size of the piezoelectric plate
102
is changed to suppress the spurious responses, the thickness of the piezoelectric block
111
must also be changed. Thus, the adjustment of the length of the piezoelectric plate
102
is very difficult to perform.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide an electronic component in which the reliability of electrical connection of an electrode provided on the upper surface of a member of the electronic component, such as a piezoelectric member, to an electrode provided on the lower surface of the member is greatly improved. Moreover, the size of the member of the electronic component is easily adjusted while eliminating the problems experienced with the conventional techniques described above.
Preferred embodiments of the present invention provide an energy-trap type piezoelectric resonator in which surface mounting is easily performed onto a mother board at least from one main surface of the resonator, the reliability of the electrical connection between the electrodes provided on the main surfaces is very high, the longitudinal size of the piezoelectric member is easily adjusted, and therefore, undesirable spurious responses are easily eliminated when the size of the resonator is reduced.
According to a preferred embodiment of the present invention, an electronic component includes a member having upper and lower surfaces opposed to each other, a pair of side surfaces opposed to each other, and a pair of end surfaces opposed to each other, the pair of side surfaces extend in the longitudinal direction of the member and are opposed to each other in the width direction of the member, a first electrode provided on the upper surface of the member of the electronic component, a flat plate-shaped first inner electrode layer film which is exposed at the upper surface of the member of the electronic component at a desired region in the width direction so as to be electrically connected to the first electrode, said first inner electrode layer extending from the upper surface to the lower surface, and the first inner electrode layer being exposed at the lower surface at a desired region in the width direction, and a connecting electrode provided on the lower surface of the member of the electronic component and electrically connected to the first inner electrode film.
Preferably, the electronic component further includes a second inner electrode layer arranged opposite to the first inner electrode layer via a layer of the member of the electronic component.
Also, preferably, the first inner electrode film extends in a direction that is substantially perpendicular to the upper surface of the member of the electronic component.
At least one of the first inner electrode layer and the second inner electrode layer is preferably arranged to intersect the upper surface at an angle of less than about 90°.
According to another preferred embodiment of the present invention, a energy-trap type piezoelectric resonator includes a piezoelectric body having an upper surface, a lower surface, a pair of side surfaces opposed to each other, and a pair of first and second end surfaces opposed to each other, the pair of side surfaces extending in the longitudinal direction of the piezoelectric member and oppo

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