Metal working – Barrier layer or semiconductor device making – Barrier layer device making
Reexamination Certificate
2001-11-14
2003-09-09
Nguyen, Ha Tran (Department: 2812)
Metal working
Barrier layer or semiconductor device making
Barrier layer device making
C361S520000, C361S540000
Reexamination Certificate
active
06616713
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for fabricating a chip type solid electrolytic capacitor and an apparatus for performing the same method, and more particularly to a welding method for connecting an anode terminal and an anode lead of the solid electrolytic capacitor.
2. Description of the Prior Art
An example of a conventional method for fabricating a chip type solid electrolytic capacitor, which may be referred to as merely “chip type capacitor” sometimes in this description, is disclosed in Japanese Patent No. 3084895. The fabrication method of chip type capacitor disclosed therein includes the step of putting an anode lead extending from a capacitor element on a connecting portion, which is formed by bending up a portion of the anode terminal, and the step of welding the connecting portion and the anode lead together by laser light.
However, since, in the conventional method, the connecting portion and the anode lead are positioned relatively with loose contact of them and welded together by laser light, there may be a case where the anode lead cannot be in sufficient area contact with the connecting portion during the welding operation. If the welding is performed in such state, there is a problem that a sufficient bonding strength cannot be obtained and, as a result, the quality of a chip type capacitor is degraded.
Further, in the disclosed conventional fabrication method, there may be a case where, in welding the anode lead and the connecting portion together by laser light, the laser light may be reflected by a weld portion and reflected laser light may irradiate other portion of the capacitor element undesirably. Particularly, when the reflected laser light irradiates the capacitor body of the capacitor element, a problem that the quality of the capacitor body and hence the chip type capacitor is degraded occurs.
SUMMARY OF THE INVENTION
The present invention was made in view of the state of the prior art and has an object to provide a method for fabricating a high quality chip type solid electrolytic capacitor and a fabrication apparatus for performing the same fabrication method.
In order to achieve the above-mentioned object, a fabrication method of a chip type solid electrolytic capacitor, according to a first aspect of the present invention, is featured by comprising the steps of putting an anode lead, which extends from a capacitor body of a capacitor element of the chip type solid electrolytic capacitor on a connecting portion, which is formed by bending a portion of an anode terminal and welding portions of the connecting portion and the anode lead together with using laser light while the anode lead is urged to the connecting portion in a region between the weld portion of the connecting portion and the capacitor body.
Since the laser light welding operation is performed while the anode lead is urged to the connecting portion, it is possible to always perform the welding operation while the anode lead is in firm contact with the connecting portion. Therefore, degradation of bonding strength can be avoided.
Consequently, it is possible to obtain a high quality chip type solid electrolytic capacitor.
Further, since the anode lead is pressingly held between the weld portion and the capacitor body, it is possible to improve the freedom of irradiating direction of laser light. On the other hand, it has been known in the fabrication of chip type solid electrolytic capacitors that a plurality of capacitor bodies bonded to a metal plate of such as aluminum, which may be referred to as “aluminum holder”, are processed through respective fabrication steps. In such case, anode leads thereof are not in one and the same horizontal plane due to bending or warping of the bonding portions of the anode leads to the aluminum holder and, therefore, the contacting state of the anode leads with the connecting portions is unstable. In the present invention, when the pressing force is selected to a value enough to correct such bending and/or warping of the anode lead, the bending and/or warping of the anode lead can be corrected, so that the welding operation can be performed in the state where the anode lead is always in firm contact with the connecting portion.
A fabrication method for fabricating a chip type capacitor, according to a second aspect of the present invention, including the step of mounting an anode lead extending from a capacitor body of a capacitor element on a connecting portion formed by bending up a portion of an anode terminal and welding the connecting portion and the anode lead together by irradiating them with laser light, is featured by that the laser welding operation is performed in the state where a reflection plate having a slot and functioning to reflect reflected laser light is arranged between a weld portion of the connecting portion to be welded and the capacitor body while the anode lead is received in the slot.
Since, in this case, the laser welding operation is performed in the state where the reflection plate having the slot and functioning to reflect reflected laser light is arranged between the weld portion and the capacitor body while the anode lead is received in the slot, the reflection plate prevent irradiation of the capacitor body with reflected laser light, so that degradation of the capacitor body is prevented.
Consequently, it is possible to obtain a high quality chip type solid electrolytic capacitor.
A fabrication method for fabricating a chip type capacitor, according to a third aspect of the present invention, including the steps of mounting an anode lead extending from a capacitor body of a capacitor element on a connecting portion formed by bending up a portion of an anode terminal and welding a weld portion of the connecting portion and the anode lead together by irradiating them with laser light, is featured by that the laser welding operation is performed in the state where a reflection plate having a slot is arranged in a region between the weld portion and a capacitor body while the anode lead is received in the slot and the anode lead is urged to the connecting portion.
Since, in this case, the laser welding operation is performed in the state where the reflection plate having the slot is arranged in the region between weld portion and the capacitor body while the anode lead is received in the slot such that the anode lead is urged to the connecting portion, the bending and/or warping of the anode lead, which occurs when a plurality of capacitor bodies bonded to an aluminum holder are processed through respective fabrication steps and makes the contact of the anode leads with the connecting portions unstable, can be corrected and the welding operation can be performed in the state where the anode lead is always in firm contact with the connecting portion. As a result, degradation of bonding strength between the anode lead and the connecting portion can be avoided. Further, since the reflection plate prevents irradiation of the capacitor body with reflected laser light, degradation of the quality of the capacitor body is prevented.
Therefore, it is possible to obtain a high quality chip type solid electrolytic capacitor.
A fabrication method for fabricating a chip type capacitor, according to a fourth aspect of the present invention, relates to any one of the first to third aspects and is featured by that the connecting portion includes a welding notch for receiving the anode lead and welding side portions, which are formed on both sides of the welding notch and form a weld portion, and laser light irradiates only the weld portion.
Since, in this case, only the weld portion of the connecting portion is irradiated with laser light, the weld portion of the connecting portion is melted and the molten material flows around the anode lead in the welding notch, so that the bonding strength is stabilized and the utility of thereof is improved. Further, it becomes possible to restrict temperature rise of the anode lead to the irreducible minimum of the demand to ther
Kono Takashi
Sano Mitsunori
Watanabe Kazunori
NEC Tokin Corporation
Nguyen Ha Tran
LandOfFree
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