Electronic component

Details Electronic component Electronic component

1998-10-16

2001-08-14

Budd, Mark O. (Department: 2834)

Electrical generator or motor structure

Non-dynamoelectric

Piezoelectric elements and devices

C310S344000

Reexamination Certificate

active

06274968

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 specifically, to an improved surface mounting type electronic component in which an electronic component element is disposed between upper and lower case substrates.
2. Description of the Related Art
In a piezoelectric resonance device, such as a piezoelectric resonance element, a piezoelectric resonance element is packaged and sealed in such a way that oscillation thereof is not hindered in order to allow the piezoelectric resonance element to be surface-mounted on a printed circuit board or the like and to improve the environmental compatibility of the resonance element.
For example, Japanese Patent Laid-Open No. 4-70107 (Japanese Patent Application No. 2-183124) discloses a piezoelectric resonance device having a construction as shown in FIG.
11
. In a piezoelectric resonance device
71
, a piezoelectric resonance element
74
is formed by disposing resonance electrodes
73
a
and
73
b
on the major surfaces of a piezoelectric substrate
72
which has a rectangular plate shape. As shown in
FIG. 12
, in the piezoelectric resonance element
74
, the resonance electrode
73
a
is provided at the center of one of the major surfaces of the piezoelectric substrate
72
and connected to a lead electrode
73
d
through a conductive connection portion
73
c
. Spaces
75
a
and
75
b
for allowing free and unhindered vibration are provided on the upper and lower sides of the piezoelectric resonance element
74
. An upper case substrate
76
a
and a lower case substrate
76
b
which comprise rectangular plates having the same size as the piezoelectric substrate
72
are stacked together. External electrodes
77
and
78
are provided on an exterior of the piezoelectric resonance device
71
.
Further, Japanese Utility Model Laid-Open No. 5-25818 (Japanese Utility Model Application No. 3-81444) discloses a piezoelectric resonance device as shown in FIG.
13
. In this piezoelectric resonance device
81
, a piezoelectric resonance element
83
is disposed in a case
82
having an upper opening. The upper opening of the case
82
is closed by joining a cover member
85
thereto via adhesive
84
.
Further, Japanese Utility Model Laid-Open No. 4-69921 (Japanese Utility Model Application No. 2-113616) discloses a piezoelectric oscillation component as shown in FIG.
14
. In this piezoelectric oscillation component
91
, a case includes a case substrate
92
in the form of a rectangular plate and a rectangular-prism-shaped case member
93
having a lower opening and joined to the upper portion of the case substrate
92
. A piezoelectric resonance element
94
is mounted on the case substrate
92
.
Further, Japanese Utility Model Laid-Open No. 6-5215 (Japanese Utility Model Application No. 4-49012) discloses a chip-type piezoelectric oscillator
101
as shown in FIG.
15
. In the chip-type piezoelectric oscillator
101
, a piezoelectric element
102
in the form of a rectangular plate is sandwiched between case substrates
103
and
104
which are composed of rectangular plates. The side surfaces of the piezoelectric oscillator
101
are inclined in order to prevent external electrodes
105
and
106
from being separated when the piezoelectric oscillator
101
is mounted on a printed circuit board.
In the piezoelectric resonance device
71
shown in
FIG. 11
, the piezoelectric resonance element
74
and the upper and lower case substrates
76
a
and
76
b
have the same size. Thus, when assembling the device, the alignment of the piezoelectric resonance element
74
with the upper and lower case substrates
76
a
and
76
b
is rather difficult to perform. When the piezoelectric resonance element
74
and the upper and lower case substrates
76
a
and
76
b
are assembled such that there is a deviation in alignment between any of the element
74
and substrates
76
a
,
76
b
, cracks, chips, and other problems are generated in the piezoelectric resonance element
74
when it is handled.
In the piezoelectric resonance device
81
shown in
FIG. 13
, the piezoelectric resonance element
83
is disposed in a case, so that cracks, chips, and other problems are not easily generated in the piezoelectric resonance element as in the above described case. However, since the piezoelectric resonance element
83
is disposed in a case which is larger than the resonance element
83
, it is extremely difficult to meet the demand for a reduction in size of the component.
Similarly, in the piezoelectric resonance device
91
shown in
FIG. 14
also, it is rather difficult to meet the demand for a reduction in size due to the construction in which the piezoelectric resonance element
94
is arranged in the case formed by the lower case substrate
92
and the case member
93
.
The piezoelectric oscillator
101
shown in
FIG. 15
has the same problem as the piezoelectric resonance device shown in
FIG. 12
although the sizes of the piezoelectric element
102
and the upper and lower cases
103
and
104
are different. That is, in the piezoelectric oscillator
101
, the joining areas are the same in the joint section where the piezoelectric element
102
is joined to the lower case substrate
103
. Further, in the joint section where the piezoelectric element
102
is joined to the upper case substrate
104
, the areas of the portions corresponding to the joint interface are the same. Thus, the alignment of these portions is extremely difficult to perform. When the alignment is not performed in a satisfactory manner, cracks, chips, and other problems are liable to be generated in the piezoelectric element
102
when the oscillator is handled.
The above problems are experienced not only in surface mounting type electronic components using piezoelectric elements but also in surface mounting type electronic components using other electronic component elements.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of the present invention provide an electronic component in which surface mounting is possible by using a case member wherein the positioning of the electronic component element with respect to the case member is easy to perform such that cracks, chips, and other problems are not generated in the electronic component element when there is some positionally deviation between the electronic component and the case member, and wherein it is possible to achieve a significant reduction in size of the electronic component.
One preferred embodiment of the present invention provides an electronic component, including an electronic component element, upper and lower case substrates stacked on each other with the electronic component element disposed therebetween, the electronic component, the upper case and the lower case including substantially rectangular members, wherein relationships a
0
<a
1
and b
0
<b
1
are satisfied where a length of shorter sides and a length of longer sides of the electronic component element are a
0
and b
0
, respectively, and a length of shorter sides and a length of longer sides of the lower case substrate are a
1
and b
1
, respectively.
According to the electronic component described above, the length of the shorter sides and the length of the longer sides of the electronic component element are respectively smaller than the length of the shorter sides and the length of the longer sides of the lower case substrate, so that, when securing the electronic component element to the lower case substrate, the positioning is easily effected and reliably achieved. That is, since the electronic component element is smaller than the lower case substrate, cracks, chips, and other problems are not generated even if there is some positionally deviation in the electronic component element, as long as the electronic component element does not protrude sideways from the outer peripheral edge of the lower case substrate.
Thus, in an electronic component including an electronic component element disposed

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