Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
2000-08-22
2001-09-18
Reichard, Dean A. (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S301300, C361S272000, C361S330000, C361S275200
Reexamination Certificate
active
06292348
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surface mounted capacitor, and more particularly to a surface mounted capacitor that is automatically manufactured by a surface mounting technique.
2. Description of the Related Art
Taiwan Utility Model Publication No. 266300 issued on Dec. 03, 1995 and entitled “SURFACE INSERT TYPE CHIP CAPACITOR”, as shown in
FIG. 1
of the drawings, discloses a surface mounted capacitor comprising a casing
10
, a dielectric medium
20
, a layer of rubber
30
, and a support base
40
. The casing
10
is made of metal and covered by an insulating film. The dielectric medium
20
includes a charged layer
21
, an insulating layer
22
, and two leads
23
. The dielectric medium
20
is mounted inside the casing
10
and rubber
30
is provided to seal the dielectric medium
20
inside the casing
10
after filling of electrolyte. The casing
10
is rolled at a portion thereof so as to be stuck into the rubber
30
to form an annular groove
11
for preventing the rubber
30
from moving out of the casing
10
. The support base
40
is mounted to an opening of the casing
10
with the leads
23
extended through the rubber
30
and then rested on an outer surface of the support base
40
after bending. Nevertheless, the casing
10
is made of metal such that the length of the insulating layer
22
must be longer than that of the charged layer
21
so as to avoid short circuit resulting from contact between the charged layer
21
of the dielectric medium
20
and the casing
10
. In addition, the support base
40
is necessary for fixing the leads
23
, which increases the overall length and volume of the capacitor. Further, the capacitance of the dielectric medium will be conducted outside and thus cannot be stored if the insulating film on the outer surface of the casing
10
is damaged. The good production rate for the capacitors is thus lowered. Further, the electrolyte in the casing
10
is kept inside the casing
10
by means of sealing between the annular groove and the rubber
30
. Leaking of the electrolyte is likely to occur due to improper rolling or fatigue of the rubber. The good production rate is thus poor.
FIGS. 2 and 3
illustrate another conventional surface mounted capacitor that includes a casing
50
, a dielectric medium
60
, a layer of glue
70
, and a cover
80
. The casing
50
includes a lateral side
51
, a first end face
52
, and a second end face
53
. The second end face
53
includes an opening
54
. The dielectric medium
60
is firstly mounted into the casing
50
and a stop plate
55
is then provided to enclose the dielectric medium
60
. The glue
70
is applied to the first end face
52
and fills the casing
50
in a manner shown in FIG.
3
. Two leads
61
of the dielectric medium
60
extend out of the stop plate
55
and the glue
70
and then rest on the lateral surface
51
of the casing
50
after bending along the first end face
52
. The electrolyte is filled into the casing
50
via the opening
54
, and the cover
80
is then provided to seal the casing
50
. Alternatively, the material around the opening
54
may be heated and thus seal the opening
54
by means of using a high-temperature die.
Nevertheless, during filling of the glue, a recessed area is formed in the first end face
52
of the casing
50
after hardening of the glue
70
due to surface tension. As a result, the portions of the leads
61
along the first end face
52
are not planar and thus not suitable to surface mounting technique (SMT). Further, a protruded section is formed on the second end face
53
of the casing
50
after mounting of the cover
80
or sealing by means of fusion. This is not suitable to a suction/holding mechanism used in SMT. As a result, the capacitor is only useable in the portion of the leads
61
along the lateral side
51
of the casing
50
, and the suction/holding mechanism used in SMT can only hold the planar portion along the lateral side
51
of the casing
50
. Application of the capacitor is thus limited.
SUMMARY OF THE INVENTION
The casing of the capacitor is made of insulating material such that the insulating layer of the dielectric medium needs not to be lengthened to thereby avoid short circuit resulting from contact between the charged layer and the casing. The overall volume is thus reduced. In addition, each face of the casing of the capacitor is planar such that a suction/holding mechanism can be used to hold the casing by means of sucking, thereby allowing wider application of the capacitor.
It is, therefore, the primary object of the present invention to provide a surface mounted capacitor with a simpler structure and made from insulating material. The number of elements is reduced to thereby reduce the overall volume for achieving the purpose of reducing the overall height.
It is another object of the present invention to provide a surface mounted capacitor with a simpler structure, wherein the casing of the capacitor has a larger opening to allow rapid, accurate filling of electrolyte into the casing. The assembly procedure is thus simpler and quicker and the good production rate is improved.
It is a further object of the present invention to provide a surface mounted capacitor having a casing with a completely flat face to be sucked and thus held by a suction/holding mechanism used in SMT, such that the capacitor in accordance with the present invention can be used in various processes of SMT.
A capacitor in accordance with the present invention comprises a casing, an inner board, a dielectric medium, and an outer board. The casing includes a peripheral wall and an end face to thereby define a compartment with an opening. The end face includes two grooves each having a through-hole through which an associated one of two legs of the dielectric medium extends. The peripheral wall includes a through-hole communicated with the compartment. An inner periphery defining the compartment includes a peripheral flange for positioning the inner board. In assembly of the capacitor, the inner board and the dielectric medium are placed into the compartment of the casing, respectively, with the two leads of the electric medium extended beyond the end face of the casing via holes of the inner board. Resin glue is poured into the compartment via the through-hole. The resin glue fills the compartment and is between the inner board and the end face. Electrolyte is filled into the compartment via the opening of the casing and the outer board is used to cover the opening. The leads are then provided with electricity to age (charge) the dielectric medium and to proceed with tests. Then, the leads are bent to be located in the grooves in the end face, respectively. A suction/holding mechanism of surface mounting technique (SMT) can be used to hold a portion of the outer board by suction for mounting the capacitor to an apparatus.
REFERENCES:
patent: 4673900 (1987-06-01), Blamire et al.
patent: 4812941 (1989-03-01), Rice et al.
patent: 5683834 (1997-11-01), Fujimoto et al.
Bacon & Thomas PLLC
Ha Nguyen T
Reichard Dean A.
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