Electricity: electrical systems and devices – Electrolytic systems or devices – Solid electrolytic capacitor
Reexamination Certificate
2001-04-04
2002-08-06
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrolytic systems or devices
Solid electrolytic capacitor
C361S529000
Reexamination Certificate
active
06430034
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chip capacitor, a fabrication method for the same, and a metal mold.
2. Description of the Related Art
Japanese Unexamined Patent Application, First Publication No. Sho 60-66807 is a publication relating to a conventional capacitor. In this capacitor, a anode terminal embedded in the capacitor element is connected to a positive terminal, and provided with an external resin package with resin packaging provided such that the cathode terminal side of the capacitor element is connected to the negative terminal. In addition, Japanese Unexamined Patent Application, First Publication No. Sho 60-220921, is another publication related to conventional capacitors. This capacitor is provided with an external resin packaging such that the electrode surfaces on both sides of the capacitor element are connected to both terminals.
However, in recent years electronic devices such as mobile telephones require increasingly high functionality and at the same time decreasing weight, and the capacitors used in the electronic devices must also become smaller and more lightweight than they are at present.
In both of the above-described conventional capacitors, the packaging surface side of the terminal is flat, and the capacitors are soldered to printed circuit boards on this flat part. However, when the soldering is carried out using reflow soldering, there is the problem that what is termed the chip-standing phenomenon (also called the Manhattan phenomenon or the tombstone phenomenon), in which the component ends up standing on one end due to the surface tension of the solder, occurs easily. Furthermore, because this type of chip-standing phenomenon occurs particularly easily in ultra-small chips designed for small size and decreased weight, this is a problem that is inseparable from dealing with this type of small size and low weight design.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a chip capacitor, a fabrication method for the same, and a metal mold that can prevent the occurrence of the chip-standing phenomenon even when carrying out soldering using reflow soldering, and furthermore, can be adapted to reducing size and weight.
In order to attain this object, a first aspect of the invention is a chip capacitor having an external resin packaging formed such that a capacitor element is connected to both anode and cathode terminals thereof, wherein both or the terminals comprise a flat base plate that is exposed on the mounting surface side of the external resin packaging, connecting tongue pieces that rise relative to the flat plate and are connected to the capacitor element, and side piece parts that extend beyond the connecting tongue piece from the flat plate to the external end surface of the external resin packaging in a direction opposite to the flat plate, and further wherein ends of the side piece parts are exposed beyond their mounting surface sides to the external end surface of the external resin packaging at the diagonally rising side due to curved parts being formed by press processing that extend beyond the connecting tongue pieces rising in a diagonal direction relative to the connecting tongue pieces to the external end surface, and at the same time the mounting surface side is also exposed up to the external end surface.
In this manner, because curved parts being formed by press processing that extend beyond the connecting tongue pieces rising in a diagonal direction relative to the connecting tongue pieces to the external end surface, the side piece parts are exposed beyond the mounting surface to the external end surface of the external resin packaging at the side where the connecting tongue pieces rise, and at the same time, the mounting surface side is also exposed up to the external end surface.
Thereby, when the side piece parts are soldered to the printed circuit board by reflow soldering, the solder is trapped in the space under of the curved part of the side piece parts, and as a result, the occurrence of the chip-standing phenomenon can be prevented. Therefore, the occurrence of the chip-standing phenomenon can be prevented even when carrying out soldering using reflow soldering, and furthermore, this is in line with small size and decreasing weight.
Furthermore, because the curved parts are formed by press bending processing, fabrication is easy and the cost increases can be restrained.
In addition, because the structure has curved parts formed beyond the connecting tongue piece to the external end surface side of the external resin packaging, in other words, a structure in which the curved parts are interposed between the external end surface and the connecting tongue piece, a gap between the external end surface and the connecting tongue piece can be reliably opened, and positional relationships are attained in which the connecting tongue pieces can be reliably buried in the external resin packaging. As a result, the remarkable effects are attained that the capacitor element connected to a connecting tongue piece can be reliably buried in the external resin packaging, the moisture resistance can be maintained, and in particular, the leakage current characteristics can be maintained.
A second aspect of the chip capacitor of the present invention according to the first aspect is characterized in the curved parts having a bow shape.
In this manner, because the curved parts have a bow shape, the contact surface area in a curved part with the solder can be made large, and the reliability of the connection can be increased. In addition, because the curved parts are exposed, visual confirmation of the connection by the solder during packaging is easy.
A third aspect of the chip capacitor of the present invention according to the first and second aspect is characterized in the areas of both terminals exposed on the mounting surface side being equal to each other.
In this manner, because the areas of both terminals exposed to the mounting surface side are equal to each other, the contact area with the printed circuit board is equal, and as a result, the occurrence of the chip standing phenomenon during reflow soldering can be reliable prevented.
A fourth aspect of the chip capacitor of the present invention according to the first through third aspects is characterized in the height of the curved parts from the mounting surface being two times the height of the thickness of the base plate or greater.
In this manner, because the height of a curved part from the mounting surface is two times the height of the thickness of the base plate or greater, the solder can be sufficiently trapped in the space under the curved parts, and as a result, the occurrence of the chip standing phenomenon during reflow soldering can be reliably prevented.
A fifth aspect of the chip capacitor of the present invention according to the first through fourth aspects is characterized in the terminal of the cathode having a buried plate that is buried in the external resin packaging parallel to the base plate after being bent in the upward direction relative to the connecting tongue on the side of the base plate opposite to the side piece parts.
Thereby, because the terminal of the cathode is buried in the external resin packaging in the buried part parallel to the base plate in the upward direction relative to the connecting tongue piece, the occurrence of pealing of the terminal from the external resin packaging can be prevented.
A sixth aspect of the chip capacitor of the present invention according to the first through fifth aspects is characterized in a convex dam that projects to the capacitor element side and abuts the mounting surface side of the capacitor element being formed on the base plate.
In this manner, because a convex dam that projects to the capacitor element side and abuts the mounting surface side of the capacitor element is formed on the base plate, when the capacitor element and the base plate are attached using a conducting adhesive such as gold paste, unnece
Mine Kazuhiro
Sano Mitsunori
Sato Hideaki
Watanabe Kazunori
Dinkins Anthony
Hayes & Soloway P.C.
NEC Corporation
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