Metal working – Barrier layer or semiconductor device making – Barrier layer device making
Reexamination Certificate
2000-02-09
2002-06-25
Nguyen, Ha Tran (Department: 2812)
Metal working
Barrier layer or semiconductor device making
Barrier layer device making
C029S025010, C029S025020, C264S328800, C264S272180, C264S272210, C361S539000, C361S540000
Reexamination Certificate
active
06409775
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a machine for manufacturing a solid electrolytic capacitor; more specifically, a method of encapsulating the electrolytic capacitor elements mounted on a hoop metal lead frame with a molding resin.
BACKGROUND OF THE INVENTION
A method for manufacturing a solid electrolytic capacitor that uses a conductive high polymer material for the solid electrolyte is described as an example of the conventional manufacturing method, referring to FIG.
6
and FIG.
7
.
FIG. 6
is a plan view showing part of a hoop metal lead frame mounted with an element for solid electrolytic capacitor. A metal lead frame
16
has a terminal section
18
provided continuously at a certain regular interval along the direction of length, and a crosspiece
19
between respective terminal sections
18
for connecting both sides of the metal lead frame in terms of the width direction. The terminal section
18
is mounted with a capacitor element
17
, with electrode of the capacitor element
17
connected to the terminal section
18
. A perforation
20
is for transferring the lead frame
16
.
FIG. 7
is a partial plan view used to describe a method of encapsulating the capacitor element
17
of
FIG. 6
with a molding resin. A main runner
21
lies close to the metal lead frame
16
along one of the sides, and a plurality of sub runner
22
branch-out from the main runner
21
covering every other crosspiece
19
. Molding resin is injected from the sub runner
22
through a gate portion
23
. The capacitor element
17
is encapsulated with the molding resin forming a solid electrolytic capacitor
24
on the lead frame
16
. Removal of the main runner
21
and the sub runner
22
provides finished pieces of the solid electrolytic capacitor.
In the above described conventional method of manufacture, the solid electrolytic capacitors
24
formed on the metal lead frame
16
are connected with the main runner
21
, the sub runner
22
and the gate portion
23
, as shown in FIG.
7
. The first action needed to divide the capacitors
24
into individual pieces is to separate the main runner
21
and the sub runner
22
from the solid electrolytic capacitors
24
formed on the metal lead frame
16
. The action of removing the runners
21
,
22
generates following problems.
A force exerted to peel the main runner
21
and the sub runner
22
off the metal lead frame
16
inevitably gives an unwanted force to the crosspiece
19
covered with the sub runner
22
. The unwanted force ill affects the solid electrolytic capacitors
24
. Namely, the tight adhesion between the molding resin and the lead frame
16
is deteriorated, and the hermetic sealing property of the resin-encapsulated capacitor elements
17
is degraded.
A conventional countermeasure taken to solve the above problem is to provide a blasting on the metal lead frame
16
in the area to be covered by the molding resin, for the purpose of increasing the adhesive strength to resin. However, such a countermeasure has not been effective enough to totally eliminate the adverse influence of the force exerted on the solid electrolytic capacitors
24
through said crosspiece
19
. So, under the conventional method, it has been difficult to provide a sufficient assurance on the quality of solid electrolytic capacitors
24
with respect to the liermetic sealing property. Meanwhile, if one wants to separate the runners
21
,
22
from the metal lead frame
16
without leaving unwanted force on the solid electrolytic capacitors
24
, an expensive machine of complicated structure will be required.
The present invention aims to offer a method for manufacturing the solid electrolytic capacitors, as well as a machine for the manufacture, which can provide the solid electrolytic capacitors on the stable basis that are superior in the reliability with respect to the hermetic sealing property.
SUMMARY OF THE INVENTION
A method for manufacturing a solid electrolytic capacitor in accordance with the present invention is providing a metal lead frame with a crosspiece between every two capacitor elements along the length direction of the lead frame, providing a sub runner, which is branching out from a main runner, in a region where there is no crosspiece, and injecting a molding resin onto the capacitor elements via the sub runner. Under the above described method of manufacture, since the sub runner is not covering the crosspiece, the lead frame is not affected by unwanted forces when separating both runners from the lead frame on which the capacitor elements have been integrated. Therefore, the hermetic sealing property is not ill affected, and the solid electrolytic capacitors thus manufactured will have a superior reliability.
In the above described manufacturing method of the present invention, it is preferred to provide the metal lead frame with a reference hole at the starting point and the ending point of a span corresponding to a number of capacitor elements that can be molded at one shot, for detecting dislocation in the transfer pitch; and transferring the metal lead frame for the number of capacitor elements accordingly. The reference holes may be detected by a sensor for preventing the transfer pitch dislocation. Thus the molding operation may be conducted efficiently at a higher precision level.
When joining metal lead frames, it is preferred to have the reference hole at the end of a first lead frame and the reference hole at the beginning of a second lead frame coupled together. By joining two metal lead frames in this way, the molding operation may be carried out continuously without halting at the joint of two lead frames, or discarding the molded elements of that sector. This contributes to a further increased productivity and yield rate.
It is also preferred to provide the reference hole at only one side, in terms of the width direction, of a metal lead frame. With this configuration, a reversed lead frame can be easily detected, and the occurrence of a trouble may be prevented.
The metal lead frame having the resin-encapsulated capacitor elements is severed from the sub runner, in a manner where the sub runner is peeled off the metal lead frame while at least the metal lead frame is held firm. Since the sub runner is not covering a crosspiece, no unwanted force is given on the metal lead frame during the severance operation.
A machine for manufacturing a solid electrolytic capacitor in accordance with the present invention comprises transfer means for transferring resin-encapsulated capacitor elements integrated on a metal lead frame molded through a main runner and a sub runner, holding means for holding the metal lead frame from the upper and the bottom surfaces having an escape portion for avoiding making contact with the sub runner, and guiding means disposed at a place in the down stream of the holding means provided for guiding the main runner. The metal lead frame is severed from the sub runner by making use of the holding means. Since the severance is conducted by the guiding means, structure of the present manufacturing machine is quite simple. Thus the solid electrolytic capacitors having a superior hermetic sealing property can be manufactured for an inexpensive cost with ease.
A metal lead frame used in the manufacturing method of the present invention is provided with a plurality of terminal sections stretching in terms of the width direction, being disposed along the length direction, and a plurality of crosspieces bridging the both sides in terms of the width direction, being disposed one crosspiece for every two terminal sections along the length direction.
REFERENCES:
patent: 4571662 (1986-02-01), Conquest et al.
patent: 5198967 (1993-03-01), Kuranuki et al.
patent: 6177723 (2001-01-01), Eng et al.
Kuranuki Kenji
Tasei Masatoshi
Nguyen Ha Tran
Ratner & Prestia
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