U.S. patent application number 09/843109 was filed with the patent office on 2001-11-29 for capacitor termination assembly.
Invention is credited to Cadwallader, John, Clark, Kyle, Kormendy, Tibor, Richard, Michel.
Application Number | 20010044994 09/843109 |
Document ID | / |
Family ID | 24309981 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010044994 |
Kind Code |
A1 |
Kormendy, Tibor ; et
al. |
November 29, 2001 |
Capacitor termination assembly
Abstract
A capacitor includes a pellet molded within a protective
material and having a cathode termination surface at one end and an
anode wire extending from the other end. The cathode termination
surface is centered with respect to the longitudinal axis of the
capacitor. The method includes centering the pellet body and a tear
drop shaped conductive cathode element within a mold and molding a
protective coating around them. After the molding is complete a
portion of the tear drop shaped member is removed to create a
cathode termination.
Inventors: |
Kormendy, Tibor; (Kennebunk,
ME) ; Richard, Michel; (Kennebunk, ME) ;
Cadwallader, John; (Kennebunk, ME) ; Clark, Kyle;
(Milford, CT) |
Correspondence
Address: |
ZARLEY MCKEE THOMTE VOORHEES & SEASE PLC
SUITE 3200
801 GRAND AVENUE
DES MOINES
IA
50309-2721
US
|
Family ID: |
24309981 |
Appl. No.: |
09/843109 |
Filed: |
April 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09843109 |
Apr 25, 2001 |
|
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09577745 |
May 23, 2000 |
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Current U.S.
Class: |
29/25.03 |
Current CPC
Class: |
H01G 9/15 20130101; H01G
9/012 20130101 |
Class at
Publication: |
29/25.03 |
International
Class: |
H01G 009/00 |
Claims
What is claimed is:
1. A capacitor comprising: a capacitor pellet having an anode end,
a cathode end, a front face, a rear face, first and second opposite
sides, and a longitudinal pellet axis extending from said cathode
end to said anode end; an anode wire connected to and in contact
with said pellet and extending outwardly from said anode end of
said pellet; a quantity of conductive material in electrical
contact with said cathode end of said capacitor pellet; a molded
material covering said pellet and also covering a portion of said
conductive material; said front face, said rear face, and said
first and second opposite sides of said capacitor pellet being
substantially centered within said molded material; said conductive
material being uncovered by said molded material to create an
exposed cathode termination at said cathode end of said pellet,
said cathode termination being approximately centered on said
longitudinal axis of said pellet and facing axially away from said
cathode end of said pellet; a cathode terminal covering said
cathode pellet end and all of said conductive material and being in
electrical contact with said cathode termination.
2. A capacitor according to claim 1 wherein said quantity of
conductive material surrounds and contacts said front face, said
rear face, and said first and second opposite sides of said pellet
adjacent said cathode end of said pellet.
3. A capacitor comprising: a capacitor pellet having a pellet anode
end, a pellet cathode end, a pellet front wall, a pellet rear wall,
and first and second opposite pellet side walls; an anode wire in
electrical connection with said capacitor pellet and extending from
said anode end of said pellet; a conductive material surrounding
and being in electrical contact with said cathode material at said
pellet cathode end and at portions of said pellet front, rear, and
first and second side walls adjacent said pellet cathode end; a
molded material surrounding and covering said capacitor pellet and
leaving an exposed portion of said conductive material uncovered to
form a cathode termination, said dielectric material surrounding
and covering a covered portion of said conductive material.
4. A capacitor according to claim 3 wherein said covered portion of
said conductive material is on said pellet front, rear, and first
and second side walls, and said uncovered portion of said
conductive material is on said pellet cathode end and faces axially
away from said pellet cathode end.
5. A method for making a capacitor comprising: forming a capacitor
pellet having a pellet anode end, a pellet cathode end, a pellet
front wall, a pellet rear wall, first and second opposite pellet
side walls, and a longitudinal axis extending between said pellet
anode and cathode ends; connecting an anode wire to said anode end
of said pellet with said anode wire extending from said anode end
of said pellet; applying a fluid conductive material capable of
hardening to said cathode end and the portions of said pellet front
wall, rear wall, first side wall, and second side wall adjacent
said cathode end of said pellet to create a tear drop shaped
conductive body having a tear drop point extending axially away
from said cathode end of said pellet; permitting said fluid
conductive material to harden; molding a protective material to
form a protective coating around said capacitor pellet and said
tear drop shaped conductive body; removing a portion of said tear
drop point and said protective coating to form an exposed cathode
termination surface from said conductive body.
6. A method according to claim 5 wherein said removing step further
comprises forming said cathode termination surface into a flat
surface facing axially away from said pellet cathode end.
7. A method according to claim 6 wherein said removing step is
accomplished by making a cut through said dielectric material and
said hardened conductive material to expose said cathode
termination surface.
8. A method according to claim 6 wherein said removing step is
accomplished by grinding said tear drop point and said protective
coating which covers said tear drop point.
9. A method according to claim 5 and further comprising attaching a
conductive cathode terminal over said cathode end of said pellet
and in electrical contact with said cathode termination
surface.
10. A method according to claim 5 wherein said molding step
comprises centering said pellet in a mold in spaced relation to the
walls of said mold to create a space between said pellet and said
mold, and filling said space with said protective material.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a capacitor termination and
method for making same.
[0002] Presently known techniques for forming a cathode termination
on a capacitor often result in off center cathode termination
surfaces. These off center terminations can result in
inconsistencies in the performance of the capacitors and is
undesirable.
[0003] Therefore a primary object of the present invention is the
provision of an improved capacitor termination and method for
making same which permits the molding of a protective material
around the capacitor pellet with a substantially uniform
thickness.
[0004] A further object of the present invention is the provision
of an improved capacitor termination and method for making same
which results in a cathode termination that is centered with
respect to the capacitor body.
[0005] A further object of the present invention is the provision
of an improved capacitor having a low ESR.
[0006] A further object of the present invention is the provision
of an improved capacitor termination and method for making same
which is economical, efficient in operation, and simple in
operation.
SUMMARY OF THE INVENTION
[0007] The foregoing objects may be achieved by a capacitor
comprising a capacitor pellet having an anode end a cathode end, a
front face, a rear face, first and second opposite sides, and a
longitudinal pellet axis extending from the cathode end to the
anode end. An anode wire is connected to and in contact with the
pellet and extends outwardly from the anode end of the pellet. A
quantity of conductive material is in electrical contact with the
cathode end of the capacitor pellet. A molded material covers the
pellet with a substantially uniform thickness and also covers a
portion of the conductive material at the anode end of the pellet.
The molded protective material leaves a portion of the conductive
material uncovered to create and expose a cathode termination at
the cathode end of the pellet. The cathode termination is
approximately centered on the longitudinal axis of the pellet and
faces axially away from the cathode end of the pellet. A cathode
terminal covers and is in electrical contact with the cathode
termination.
[0008] The method of the present invention comprises forming a
capacitor pellet having a pellet anode end, a pellet cathode end, a
pellet front wall, a pellet rear wall, first and second opposite
pellet side walls, and a longitudinal axis extending between the
pellet anode and cathode ends. an anode wire is connected to and
extends from the anode end of the pellet. A fluid conductive
material capable of hardening is applied to the cathode end and
portions of the pellet front wall, rear wall, first side wall and
second side wall adjacent the cathode end of the pellet. The fluid
conductive material creates a tear drop shaped conductive body
having a tear drop point extending axially away from the cathode
end of the pellet. The fluid conductive material is permitted to
harden. A protective material is molded around the pellet and the
conductive material to form a protective coating. A portion of the
tear drop point and the protective coating are then removed to form
an exposed cathode termination surface of the conductive body.
[0009] According to another feature of the invention the removing
step further comprises forming the cathode termination surface into
a flat surface facing axially away from the pellet cathode end.
[0010] According to another feature of the invention the removing
step is accomplished by cutting or by grinding the tear drop
point.
BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS
[0011] FIG. 1 is a sectional view of a capacitor made according to
the present invention.
[0012] FIG. 2 is an elevational view showing the pellet, wire, and
teardrop body of the present invention.
[0013] FIG. 3 is a simplified and partial semetric view of the
molds used to produce the capacitor of the present invention.
[0014] FIG. 4 is a top plan view of the pellet positioned within
the bottom mold member.
[0015] FIG. 5 is a sectional view taken along line 5-5 of FIG.
4.
[0016] FIG. 6 is a sectional view of the molded capacitor before
the bottom portion thereof is removed.
[0017] FIG. 7 is a view similar to FIG. 6, but showing a prior art
capacitor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] Referring to FIG. 1 the numeral 10 generally designates a
capacitor made according to the present invention. Capacitor 10
includes a pellet 12 having an anode pellet end 14, and a cathode
pellet end 16. An anode wire 18 is embedded in and extends from the
anode pellet end 14 of pellet 12. Pellet 12 also includes a pellet
front wall 20 (FIG. 5), a pellet rear wall 22, and opposite pellet
side walls 24, 26. Surrounding the pellet 12 is a protective body
28 made of molded material which protects the integrity of the
pellet 12. Numerous molding materials have been used, and they are
preferably dielectric. However, persons skilled in the art may
select a wide variety of protective molded materials without
detracting from the invention. The preferred molding compound is
manufactured by Dexter Corporation at 211 Franklin Street, Olean,
N.Y. 14760, under model number MG 53 F.
[0019] The protective body 28 includes a pair of opposite side
indentations 30, 32. Other side indentations are also formed in the
protective body 28 and will be described hereafter. Surrounding the
bottom of the pellet 12 is a cathode termination 34 made of a
conductive material which may be silver, other metals, or
conductive epoxy. A wide variety of these conductive materials are
available and are used in the industry. The preferred conductive
material for use in the present invention is a conductive epoxy
sold under the Model No. 61445, by Metech, Inc., having an address
of Rt. 401, Box 360, Elverson, Pa. 19520. The cathode termination
34 includes a downwardly presented cathode termination surface 36
which engages a cathode terminal cap 38 made of conductive
material. Cathode cap 38 includes cap side walls 40 and a cap end
wall 42. The wire 18 provides the anode termination for capacitor
10. A conductive anode cap 97 can be provided at the anode end so
as to engage the wire 18 and provide an anode terminal for
capacitor 10.
[0020] Referring to FIG. 2, the pellet 12 is shown in its form
before being placed in the mold. Pellet 12 is formed by
conventional press molding and sintering technique which are well
known in the art. The pellet 12 is covered at its cathode end 16 by
a tear drop shaped body 44 made of the above identified conductive
material. Body 44 includes an upper portion 45 which surrounds the
front, side and rear walls of the pellet 12 adjacent the cathode
end thereof. Tear drop shaped body 44 also includes a tear drop
point 46. In some cases there are multiple tear drop points 46.
[0021] The formation of tear drop shaped body 44 on the cathode end
16 of pellet 12 is accomplished by dipping pellet 12 into a
reservoir of fluid hardenable conductive material, or alternatively
by using a syringe. After application the conductive material is
permitted to cure and harden.
[0022] The pellet 12 shown in FIG. 2 is positioned within a molding
cavity formed by an upper mold 48 and a lower mold 54. Upper mold
48 includes an upper mold face 50 on its lower surface and a pair
of spacing ribs 52 which protrude downwardly therefrom. Bottom mold
54 includes a bottom mold face 56 which faces upwardly. Cavity side
walls 58, 60 and a cavity bottom wall 62 combine with the upper
mold face 50 to form a molding cavity as shown in FIG. 5.
[0023] A pair of L-shaped spacers 64 are positioned with upstanding
legs 66 extending along the cavity side walls 58, 60 and with
horizontal legs 70 extending along the cavity bottom wall 62. The
upper edges of upstanding legs 66 are each provided with a tapered
edge 68 (FIG. 5).
[0024] FIGS. 4 and 5 show the pellet 12 positioned within the mold.
In this position the L-shaped members 64 extend from the cathode
end 80 of the cavity toward the anode end 82 of the cavity, and
terminate at a point spaced from but adjacent the cathode end 16 of
the pellet 12 as can be seen in FIG. 4. The ribs 52 of the upper
mold 48 extend longitudinally approximately the same distance from
the anode end 80 of the cavity. As can be seen in both FIGS. 4 and
5 a substantially uniform space 72 is formed around all four sides
of the pellet 12. The L-shaped pieces 64 and the ribs 52 engage the
anode end of the pellet, and specifically engage the tear shaped
body 44 to center the pellet 12 within the cavity. While the ribs
52 and the L-shaped members 64 are used to center the pellet 12
within the cavity, other shapes and configurations of projections
could accomplish the same result without detracting from the
invention. The importance of centering the pellet 12 within the
cavity is that when the molding process is complete there is a
layer of protective material surrounding the pellet, and that layer
of protective material is of substantially uniform thickness.
[0025] FIG. 6 shows the completed molded uncut capacitor body
designated by the numeral 74. This capacitor body 74 is cut along a
cut line 76 to remove a lower body portion 78 and to expose the
cathode termination surface 36 that can be engaged by the terminal
cap 38 as shown in FIG. 1.
[0026] The removal of the removed body portion 78 can be
accomplished by cutting, grinding or other conventionally known
means.
[0027] The completed capacitor 10 has a cathode termination surface
36 which is flat and which faces axially away from the cathode end
of the pellet. It is also centered with respect to longitudinal
axis of the pellet. This centering is accomplished by the molding
process which utilizes the projections 52, 64 to center the pellet
and the tear dropped shaped body 44 within the mold cavity.
[0028] FIG. 7 illustrates a prior art capacitor 84 made according
to a prior art method for creating the cathode termination. The
capacitor 84 includes a pellet 86 and an anode wire 88. A
protective body 90 is molded around the pellet 86. At the cathode
end of the pellet 86 is a conductive adhesive 92 which attaches a
silver pin 94 to the pellet 86. A cut is made along cut line 96 and
this cut exposes the silver pin 94 to create the cathode
termination surface.
[0029] Neither the conductive adhesive 92 nor the silver pin 94 can
be used as a means for centering the pellet 86 in the molded body
90. Without the use of the tear drop shaped body, this process is
very difficult to center the pellet 86 in the molded body 90.
Failure to properly center the pellet 86 can result in thin spots
or even openings in the protective coating 90. In contrast the use
of the tear drop shaped body 44 and the use of the projections 64,
52 to center the body within the mold cavity creates a termination
which is centered with respect to the longitudinal access of the
pellet, and which has a protective coating 28 of uniform thickness
around the side wall of pellet 12.
[0030] In the drawings and specification there has been set forth a
preferred embodiment of the invention, and although specific terms
are employed, these are used in a generic and descriptive sense
only and not for purposes of limitation. Changes in the form and
the proportion of parts as well as in the substitution of
equivalents are contemplated as circumstances may suggest or render
expedient without departing from the spirit or scope of the
invention as further defined in the following claims.
* * * * *