Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
2003-10-01
2004-10-19
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S306300, C361S303000
Reexamination Certificate
active
06807047
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic device and interposer board suppressing the propagation of vibration caused by a piezoelectric property and electrostriction and thereby reducing noise, more particularly relates to an electronic device and interposer board suitable for an electronic device including a multilayer ceramic capacitor able to be used for an audio circuit or other circuit sensitive to noise.
2. Description of the Related Art
There have been dazzling advances made in thin film technology and multilayer technology for multilayer ceramic capacitors in recent years. Capacitors having high electrostatic capacities comparable with those of aluminum electrolytic capacitors are being commercialized. As the ceramic materials for forming the multilayer bodies of such multilayer ceramic capacitors, barium titanate and other ferroelectric materials with relatively high dielectric constants are generally being used. These ferroelectric materials, however, have piezoelectric properties and electrostriction properties, so when these ferroelectric materials are subjected to electric fields, stress and mechanical strain occur.
Further, when a multilayer ceramic capacitor using such a ferroelectric material is subjected to an AC voltage, stress and mechanical strain occurring in synchronization with the frequency of the AC voltage appear as vibration. As a result, this vibration is transmitted from the terminal electrodes of the multilayer ceramic capacitor to the board side.
An example of a multilayer ceramic capacitor is shown in FIG.
18
. In this multilayer ceramic capacitor
110
, two types of internal electrodes are alternately arranged in the multilayer body
112
. Terminal electrodes
114
,
116
connected to these internal electrodes are arranged at the ends of the multilayer body
112
. This capacitor
110
is, for example as shown in FIG.
19
and
FIG. 20
, mounted on a board
120
so as to connect the terminal electrodes
114
,
116
to the interconnect patterns
122
by solder
118
.
When such a multilayer ceramic capacitor
110
is subjected to AC voltage, stress P etc. occurs at the multilayer body
112
forming the main part of the multilayer ceramic capacitor
110
and vibration occurs along with this. This vibration is transmitted from the terminal electrodes
114
,
116
to the board
120
. The board
120
as a whole is liable to become a sound radiating surface and generate vibration sound becoming the noise N.
Such vibration sound has a detrimental effect on the performance and quality of equipment having audio circuits or other circuits sensitive to noise. Therefore, use of multilayer ceramic capacitors using ferroelectric materials for such equipment has generally been avoided.
Note that the technologies disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2000-235931, Japanese Unexamined Patent Publication (Kokai) No. 9-246083, Japanese Unexamined Patent Publication (Kokai) No. 6-55752, Japanese unexamined Patent Publication (Kokai) No. 2000-232030, Japanese Unexamined Patent Publication (Kokai) No. 2000-223357, and Japanese Unexamined Patent Publication (Kokai) No. 2000-182887 are known. However, the inventions disclosed in these publications are insufficient in respect to the suppression of the propagation of vibration caused due to the piezoelectric property and electrostriction and the reduction of noise.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electronic device able to suppress the propagation of vibration occurring due to a piezoelectric property and electrostriction and thereby reduce the occurrence of noise and an interposer board used for such an electronic device.
To achieve the above object, according to a first aspect of the present invention, there is provided an electronic device having a body having a pair of terminal electrodes and an interposer board to a front surface of which the pair of terminal electrodes are connected and having on its back surface a pair of external electrodes electrically connected to the parts where the pair of terminal electrodes are connected, wherein the terminal electrodes and the external electrodes are arranged in a positional relationship where the direction of a line connecting the pair of terminal electrodes and the direction of a line connecting the pair of external electrodes intersect.
Preferably, a pair of land patterns to which the pair of terminal electrodes are to be connected are provided on the front surface of the interposer board, and these land patterns and external electrodes are arranged in a positional relationship where the direction of a line connecting the pair of land patterns and the direction of the line connecting the pair of external electrodes intersect.
According to a second aspect of the present invention, there is provided an interposer board to a front surface of which a pair of terminal electrodes are to be connected and having on its back surface a pair of external electrodes electrically connected to parts where the pair of terminal electrodes are connected, wherein a pair of land patterns to which the pair of terminal electrodes are to be connected are provided on a front surface of said interposer board, and these land patterns and external electrodes are arranged in a positional relationship where the direction of a line connecting the pair of land patterns and the direction of the line connecting the pair of external electrodes intersect.
In the interposer board and electronic device according to the present invention, the back surface of the interposer board is provided with a pair of external electrodes connected to the parts where the pair of terminal electrodes are connected, and these are arranged in a positional relationship where the direction of a line connecting the pair of land patterns and the direction of the line connecting the pair of external electrodes intersect. Further, the electronic device is mounted on an external board by the pair of external electrodes being connected to the interconnect patterns of the external board.
Along with application of an AC voltage to an electronic device, vibration occurs due to the piezoelectric property and electrostriction of the body. In the present invention, however, since the direction of the line connecting the pair of terminal electrodes of the body and the direction of the line connecting the pair of external electrodes of the interposer board intersect, the propagation of the vibration to the external board becoming the sound radiating surface is suppressed and generation of noise from the substrate is reduced.
That is, in the present invention, by just adding the interposer board to the body and connecting the body to the external board through the interposer board, vibration transmitted from the pair of external terminals of the interposer board to the external board can be reduced and the generation of noise from the external board can be reduced. This is because the direction of vibration of the body mainly matches with the direction of the line connecting the terminal electrodes and the direction of vibration does not match with the direction of the line connecting the pair of external terminals of the interposer board.
Preferably, the pair of terminal electrodes in the body and the interposer board are connected by high temperature solder or a conductive adhesive. By the pair of terminal electrodes and the interposer board being connected by the high temperature solder or conductive adhesive, these are mechanically connected while securing conductivity.
Preferably, the front and back surfaces of the interposer board are provided with conductor patterns, solder resist is coated on the surfaces of the conductor patterns to expose at least part of the surfaces of the conductor patterns, and as a result the pair of land patterns are formed on the front surface of the interposer board and the pair of external electrodes are formed on the back surface of the interposer board. Preferably, connecting
Ahiko Taisuke
Togashi Masaaki
Dinkins Anthony
Oliff & Berridg,e PLC
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