Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
2003-02-26
2004-08-24
Reichard, Dean A. (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S301100, C361S301400, C361S321300, C361S305000, C361S311000, C361S313000
Reexamination Certificate
active
06781816
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic component that reduces equivalent series resistance (ESR) while allowing for sufficient absorption of thermal stress and mechanical stress, and is optimum for multilayer capacitors used in a switching power supply.
2. Description of the Related Art
In recent years, due to advances in compactness and improvements in large current flow of the switching power supply, the necessity for diffusing and radiating heat that generates from components mounted upon this switching power supply has arisen. Consequently, an aluminum wiring board with great heat radiating capability is generally employed for this switching power supply. However, the thermal expansion coefficient for this aluminum wiring board is large.
Accordingly, due to directly mounting upon an aluminum wiring board a ceramic component with a thermal expansion coefficient greatly differing from that of this aluminum wiring board, cracks may develop in this component due to large thermal stress generating in this component, or the aluminum wiring board may greatly transform due to thermal expansion of the aluminum wiring board itself, whereby developing cracks in this component due to mechanical stress. As a result, there were fears that reliability of the switching power supply would be lost.
Meanwhile, a ceramic capacitor element with a long life span and excellent frequency characteristics is generally utilized as a smoothing capacitor for smoothing switching power supply output. Due to the above problems, however, in the case of mounting this capacitor element upon an aluminum wiring board, one that has a pair of metallic terminals connected to this capacitor element is generally used.
Specifically, a conventional compound ceramic capacitor
100
is illustrated in FIG.
14
and
FIG. 15
, whereby the compound ceramic capacitor
100
is described below based on these drawings.
The interior of this compound ceramic capacitor
100
has a structure where two types of T-shaped internal conductors
104
and
105
illustrated in
FIG. 14
overlap via ceramic layers
103
A. A multilayer body
103
illustrated in
FIG. 15
is then formed by layering a plurality of these ceramic layers
103
A, and these internal conductors
104
are extended toward one of the four side surfaces of this multilayer body
103
. Furthermore, the internal conductors
105
are extended toward the side surface of the multilayer body
103
opposite to the side surface whereat the internal conductors
104
are extended.
Moreover, as shown in
FIG. 15
, terminal electrodes
106
, which are to be connected to the internal conductors
104
, and terminal electrodes
107
, which are to be connected to the internal conductors
105
, are respectively placed at mutually opposing side surfaces of multilayer capacitor elements
101
. As illustrated in
FIG. 15
, a pair of metallic terminals
111
,
112
that are respectively formed in an L-shape are then attached by solder or conductive adhesive in a form sandwiching two multilayer capacitor elements
101
, for example. Thus, this pair of metallic terminals
111
,
112
plays the role of absorbing and alleviating through elastic deformation the stress that generates due to thermal expansion and the like of the aluminum wiring board, and reducing the stress that generates in the ceramic multilayer capacitor elements
101
.
At the same time, accompanying improvements in large current flow for the switching power supply, a large ripple current comes to flow within the smoothing capacitor. Since this ripple current is consumed in the form of heat generation due to the equivalent series resistance (ESR) of the capacitor, which then self-heats according to charging and discharging, detrimental effects to the life of the capacitor occur.
Accordingly, recent increase in ripple currents have come to threaten the reliability of the multilayer capacitor elements
101
regardless of using the aluminum wiring board with great heat radiating capability. The above compound ceramic capacitor
100
is then greatly influenced by the electric resistance of the metallic terminals
111
and
112
, having defects that incur an increase in ESR.
Thus, even with a multilayer capacitor having a pair of metallic terminals as is used for the aluminum wiring board, reduction in ESR has come to be desired.
SUMMARY OF THE INVENTION
The present invention aims to provide an electronic component that reduces ESR while allowing for sufficient absorption of thermal stress and mechanical stress.
According to a first aspect of the present invention, an electronic component, comprising a dielectric element formed by layering dielectric layers; two types of internal conductors, which are respectively arranged within the dielectric element while separated from each other by the dielectric layers, and have a plurality of extended portions, respectively, that are extended toward a plurality of side surfaces of the dielectric element, respectively; two types of terminal electrodes, which are arranged at a plurality of side surfaces of the dielectric element, respectively; one of the two types of terminal electrodes connected to a plurality of extended portions of one of the two types of internal conductors, and the other of the two types of terminal electrodes connected to the remaining plurality of extended portions; and a pair of metallic terminals, which are respectively formed by metallic material; one of the metallic terminals connected to one of the two types of terminal electrodes, and the other of the metallic terminals connected to the remaining terminal electrodes, is provided.
According to such electronic component, operations as in the following take effect.
The electronic component according to this aspect has a structure with two types of internal conductors respectively arranged within a dielectric element, which is formed by layering dielectric layers, while separated from each other by the dielectric layers, and a plurality of extended portions, respectively, that are extended toward a plurality of side surfaces of the dielectric element, respectively, are provided to these two types of internal conductors, respectively.
Furthermore, two types of terminal electrodes are arranged at a plurality of sides surfaces of the dielectric element, respectively. One of these two types of terminal electrodes is connected to a plurality of extended portions of one of the two types of the internal conductors, and the other of these two types of terminal electrodes is connected to the remaining plurality of extended portions.
Moreover, a pair of metallic terminals are respectively formed by metallic material, of which one of the pair of metallic terminals is connected to one of the two types of terminal electrodes, and the other of the metallic terminals is connected to the remaining terminal electrodes.
Thus, according to this aspect, the elastic deformation of the metallic terminals assures absorption of the flexure and thermal expansion of the aluminum wiring board, thereby reducing thermal stress and mechanical stress that generate in the multilayer capacitor elements and stopping cracks from generating in the multilayer capacitor elements.
Furthermore, in this aspect as described above, the plurality of extended portions that are extended toward the plurality of side surfaces of the dielectric element, respectively, are provided to the two types of internal conductors, respectively, and the two types of terminal electrodes are arranged at a plurality of side surfaces of the dielectric element, respectively. Moreover, since it has a structure with these two types of internal conductors and two types of terminal electrodes connected to each other, the area of the portions connecting the internal conductors and terminal electrodes increases. Accordingly, the area of the portions connecting the terminal electrodes and metallic terminals then also increases, ultimately reducing ESR as a result.
Thus, since the area of these connecting portions increases an
Ha Nguyen T.
Reichard Dean A.
TDK Corporation
LandOfFree
Electronic component does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electronic component, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic component will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3338134