Chip capacitor

Details Chip capacitor Chip capacitor

2002-11-04

2004-05-11

Reichard, Dean A. (Department: 2831)

Electricity: electrical systems and devices

Electrolytic systems or devices

Liquid electrolytic capacitor

C361S538000

Reexamination Certificate

active

06735074

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a chip capacitor required to have a large vibration resistance, and particularly to an aluminum electrolytic chip capacitor to be mounted on a board as a surface-mounted capacitor.
BACKGROUND ART
FIGS.
16
(
a
) and
16
(
b
) are a front sectional view and a side sectional view of a conventional aluminum electrolytic chip capacitor, respectively. Aluminum electrolytic chip capacitor
21
(hereinafter called capacitor
21
) includes a capacitor element
23
, an open-bottomed cylindrical metal case
24
in which the element
23
and electrolyte for driving are accommodated, and a sealing member
25
for sealing the open end of case
24
. The capacitor element
23
is formed by winding anode foil and cathode foil (not shown) with an anode lead wire
22
a
and a cathode lead wire
22
b
connected thereto, respectively, with a separator disposed between them. A shrink portion (reduced-diameter portion)
24
a
is formed at sealing of the case
24
.
An insulated terminal plate
26
is disposed so as to abut the open end side of case
24
, and its outer surface (a bottom of the figure) has holes
26
a
and groove portions
26
b
. Through the holes
26
a
, the lead wires
22
a
and
22
b
led out of capacitor element
23
pass, and in the groove portions
26
b
, the lead wires
22
a
,
22
b
bent perpendicularly are placed. The bent portions of lead wires
22
a
,
22
b
are finished flat. In this manner, the capacitor
21
is mounted on a surface of a board (not shown).
After the conventional capacitor is mounted on the board, when a strong stress of vibration is applied thereto in the Y direction perpendicular to the X direction, i.e., the direction of connecting the lead wires
22
a
and
22
b
as shown in
FIG. 17
, the capacitor
21
vibrates like a pendulum since it is connected to the board only at two portions of the lead wires
22
a
and
22
b
. Accordingly, soldered portions of the lead wires
22
a
and
22
b
connected to the board are peeled off, which may cause breakage of the lead wires.
Another conventional capacitor includes an insulated terminal plate of housing-like shape surrounding a capacitor body with lead wires connected thereto. In this technology, it is necessary to make the outer diameter of the body substantially identical to the inner diameter of a housing portion of the terminal plate in order to improve the vibration resistance. Therefore, it is difficult to mount the capacitor body in the housing portion.
Japanese Patent Laid-Open No.9-162077 discloses a support portion that rises and extends from a periphery of an insulated terminal plate, and a projection disposed at the support portion which fits in a shrink groove portion of a capacitor. This document further discloses a capacitor including a support portion split by notches, and a capacitor including a cylindrical support portion made of resin having elasticity unitarily formed with an insulated terminal plate. These capacitors, since their support portions have annular shapes, have their capacitor bodies mounted. Since the support portions are formed only up to the shrink groove portions, these capacitors cannot stand sufficiently against vibrations in consideration of mounting in, for example, automobiles.
As shown in
FIG. 18
, when being bent along the groove portion
26
b
disposed in the insulated terminal plate
26
, the lead wires
22
a
and
22
b
are bent at acute angles only at one portion of each hole
26
a
. Therefore, the lead wires
22
a
and
22
b
, once bent and placed in the groove portions
26
b
, tend to return to their original positions due to a spring-back effect of the bent portions, and thereby generate a float t. The float t lowers soldering strength when a thin solder is applied.
Further, as shown in
FIG. 19
, in a capacitor including a dummy terminal
28
disposed on the outer surface (soldering surface or bottom surface) of the insulated terminal plate
27
, the above problem is particularly remarkable. In the worst case, the solder does not contact with the dummy terminal
28
. This may lead particularly to a serious problem since a thinner solder has been used recently.
In order to solve such problem, the lead wires
22
a
are
22
b
are bent with stronger forces, or the groove portions
27
a
in the insulated terminal plate
27
are formed deeper, thereby coping with the spring-back effect. However, such measure may invite a problem that the lead wires
22
a
and
22
b
cannot be soldered since they remain deep in the groove portions
27
a.
DISCLOSURE OF THE INVENTION
An aluminum electrolytic chip capacitor is easily mounted, has an excellent vibration resistance, and can be soldered reliably even if a lead wire is positioned deeply in a groove portion formed in an insulated terminal plate.
The capacitor includes a capacitor element including a lead wire for leading to the exterior, a metal case for accommodating the capacitor element, a sealing member to seal an open end of the metal case, and an insulated terminal plate disposed so as to abut the sealing member. The metal case has a shrink portion of annular shape formed at the sealing. The capacitor further includes a wall portion disposed at a position other than on a line in a lead wire bending direction of a periphery of the insulated terminal plate. The wall portion is equal to or higher than the height of the shrink portion, and has its inner surface abut and hold the periphery of the metal case.
The capacitor, upon being mounted on a board, stands strong against vibrations given in all directions including a direction crossing the lead wire bending direction, thereby assuring excellent reliability.


REFERENCES:
patent: 5420748 (1995-05-01), Ryu
patent: 5880926 (1999-03-01), Nishino et al.
patent: 60-148105 (1985-08-01), None
patent: 61-156224 (1986-09-01), None
patent: 5-226188 (1993-09-01), None
patent: 9-162077 (1997-06-01), None
patent: 9-190952 (1997-07-01), None
patent: 10-64756 (1998-03-01), None
patent: 11-233384 (1999-08-01), None
patent: 11-286493 (1999-10-01), None
patent: 2000-12384 (2000-01-01), None

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