JP2001110676A - Chip capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip capacitor with has a small mounting area and has a required capacitance, even with the reduced dimensions and whose anode terminal and cathode terminal are fixed firmly to a resin outer covering. SOLUTION: A cathode layer 24 is formed on the outer surface of a capacitor element 22. An anode lead 26 is made to protrude outwardly from one of the ends of the capacitor element 22. A cathode terminal 30 has two main surfaces 30a and 30b protruded. The main surface 30a is placed below the surface of the cathode layer 24 and connected to the cathode layer 24. An anode terminal 34 has two facing main surfaces 34a and 34b. The main surface 34b is placed approximately in the same plane as that of the main surface 30a and connected electrically to the anode lead 26. The main surfaces 34b and 30b of the anode terminal 34 and the cathode terminal 30 are exposed, and the capacitor element 22, the anode terminal 34 and the cathode terminal 30 are covered with a resin outer covering 42. Protrusions 32 are formed on the resin outer covering 42 contact part of the anode terminal 34 and the cathode terminal 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chip capacitor, and more particularly, to a small chip capacitor mounted on a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, for example, there is a chip capacitor as shown in FIG. This chip capacitor has a solid tantalum capacitor element 2. On the outer surface of the capacitor element 2, a cathode layer 4 is formed. Anode lead wire 6 from one end of capacitor element 2
Are drawn out of the capacitor element 2. A flat cathode terminal 8 is connected to the cathode layer 4 via a conductive adhesive (not shown). A flat anode terminal 10 is connected to the tip of the anode lead wire 6 by welding. After the connection is made in this manner, epoxy resin molding is performed by transfer molding, and the rectangular parallelepiped exterior 12 is formed.
Is formed. The plate-shaped anode terminal 10 and cathode terminal 8 are bent along the end surface of the exterior 12, and further bent toward the lower surface of the exterior 12.

[0003]

In such a chip capacitor, the cathode terminal 8 largely enters the interior of the exterior 12, and the cathode terminal 8 occupies a large space in the exterior 12. Further, since both the cathode terminal and the anode terminal are located on the end face of the exterior 12, the length of the chip capacitor is increased by the thickness of these terminals 8, 12. Further, as shown in FIG. 7, when a large number of chip capacitors are mounted side by side, soldering is performed on the side surfaces of the anode terminal 10 and the cathode terminal 8, so that a short circuit between the terminals of adjacent chip capacitors is prevented. Therefore, the arrangement pitch of each chip capacitor must be increased. Therefore, the total mounting area of each chip capacitor cannot be reduced. 2. Description of the Related Art In recent years, small portable devices such as cellular phones have been remarkably developed, and chip capacitors used in these devices are required to be further reduced in size. Therefore, in the conventional chip capacitor as described above, if an attempt is made to reduce the size, the proportion of the capacitor element 2 occupying in the exterior 12 must be reduced, and a desired capacitance may not be obtained.

According to the present invention, there is provided a chip capacitor in which a mounting area can be reduced, a desired capacitance can be obtained even if the chip is miniaturized, and an anode terminal and a cathode terminal are firmly fixed to an exterior resin. The purpose is to provide.

[0005]

A chip capacitor according to the present invention has a capacitor element, and a cathode layer having at least one flat surface is formed on an outer surface of a main body of the capacitor element. An anode drawer protrudes outward from one end of the main body. The anode lead-out body may be in the form of a column such as a cylinder or a prism, or may be in the form of a flat plate or a foil. A flat cathode terminal is electrically connected to the cathode layer. The flat cathode terminal has first and second main surfaces opposed to each other, and the first main surface is located below and parallel to the plane of the cathode layer. The electrical connection between the cathode layer and the cathode terminal is made by electrically connecting the first main surface to the plane of the cathode layer. The flat anode terminal is electrically connected to the anode lead-out body. The anode terminal has third and fourth main surfaces facing each other, and the third main surface is disposed substantially in the same plane as the first main surface. The third major surface can be located, for example, in a range from a suitable place below the cathode layer to the anode extractor. The electrical connection between the anode extraction member and the anode terminal is made by electrically connecting the anode extraction member to the third main surface. At least a part of the second and fourth main surfaces of the anode terminal and the cathode terminal are exposed, and the capacitor element, the anode terminal, and the cathode terminal are covered with an exterior resin. In at least one of the anode terminal and the cathode terminal, a contact area increasing portion is formed at a contact portion with the exterior resin. The contact area increasing portion can be formed on at least a part of each edge of the anode terminal and the cathode terminal.

According to the chip capacitor configured as above, the anode terminal and the cathode terminal are located only below the cathode layer, and both are flat. Further, the cathode terminal is directly connected to the cathode layer over a short distance. Therefore, the area occupied by the cathode terminal in the exterior resin can be reduced, and the chip capacitor can be reduced in size. In addition, since neither the cathode terminal nor the anode terminal is located on the side or end surface of the exterior resin, even when many chip capacitors are densely arranged, the pitch of each chip capacitor can be reduced, improving the mounting density. Can be done. Further, since the contact area increasing portion is formed on the terminal, the exterior resin and the terminal are firmly adhered to each other, and after the terminals are soldered to the printed circuit board, the exterior resin is peeled off from both terminals. Can be prevented.

[0007] The contact area increasing portion is formed in a convex portion,
It can be assumed that it has penetrated into the exterior resin. Only one protrusion may be formed, or a plurality of protrusions may be formed. One protrusion may be formed on one edge, or one protrusion may be formed on each of a plurality of edges. When a plurality of terminals are formed, a plurality of terminals can be formed on one edge, a plurality of protrusions can be formed on one edge, and a plurality of protrusions can be formed on each of the plurality of edges. It can also be formed.

By forming the contact area increasing portion in a convex shape, the contact area with the exterior resin is increased. Furthermore, since the convex portion has penetrated into the exterior resin, the contact area becomes larger than when the convex portion is exposed outside the exterior resin, and the terminal is firmly fixed to the exterior resin.

The contact area increasing portion may be formed in a concave portion, and the exterior resin may enter the concave portion.
Only one recess may be provided, or a plurality of recesses may be provided. One edge may be provided with one recess, or one edge may be formed on each of a plurality of edges. When a plurality of recesses are provided, one can be provided on each edge of the terminal, a plurality of recesses can be provided on one edge, and a plurality of recesses can be provided on a plurality of edges. it can.

Since the exterior resin has penetrated into the recess formed in the terminal, the contact area between the exterior resin and the terminal increases,
Both are firmly connected.

The contact area increasing portion is formed in an uneven portion, the convex portion invades the exterior resin, and the exterior resin invades the concave portion. This uneven part also,
Only one may be provided on one edge, or only one may be provided on each of a plurality of edges. A plurality can be provided. In this case, a plurality of uneven portions can be provided on one edge, and a plurality of uneven portions can be provided on a plurality of edges.

Since the concave and convex portions are in contact with the exterior resin at the respective portions, the contact area of the terminals with the exterior resin is increased. In addition, since the convex portion penetrates into the exterior resin, the contact area with the exterior resin is increasing more and more.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A chip capacitor 20 according to a first embodiment of the present invention is, for example, a chip-type tantalum capacitor, and has a capacitor element 22 as shown in FIG. The capacitor element 22 has, for example, a main body formed in a rectangular parallelepiped. This body is
2a, lower surface 22b, end surfaces 22c and 22d, and side surface 22
e, 22f. The capacitor element 22 may have another shape, for example, a semi-cylindrical structure as long as at least one surface, for example, the bottom surface 20b is formed in a plane.

A cathode layer 24 is formed on the entire peripheral surface of the capacitor element 22. An anode is formed inside the capacitor element 22, and an anode lead, for example, a tantalum wire 26 connected to the anode is connected to the capacitor element 2.
The second end face 22c is linearly drawn to the outside from the end face 22c.
When the cathode layer 24 is formed on the entire peripheral surface of the capacitor element 22, a disc-shaped cap 28 is attached to the tantalum wire 26 in order to prevent the cathode layer 22 from being formed around the lead portion of the tantalum wire 26. It is inserted and is brought into contact with the end face 22 c of the capacitor element 22. The tantalum wire 26 is formed, for example, in a columnar shape.
However, a plate-like tantalum wire can also be used. The capacitor element 22 is manufactured by a known method.

The cathode terminal 30 is arranged on the side of the capacitor element 22 below the lower surface 22b where the end face 22d exists, that is, on the end face side where the tantalum wire 26 is not drawn out. The cathode terminal 30 is a flat plate having, for example, two planar main surfaces 30a and 30b parallel to each other, for example, a rectangular one, and has a contact area increasing portion at one end thereof.
For example, the projection 32 is formed integrally. This convex part 32
Is also a rectangular shape having two main surfaces facing each other,
One main surface is located on the same plane as the main surface 30a of the cathode terminal 30. The other main surface is located closer to main surface 30a than main surface 30b of cathode terminal 30. That is, as shown in FIG. 1B, the convex portion 32 is
The thickness is smaller than 0. Further, the length of the convex portion 32 is shorter than that of the cathode terminal 30, and the width is somewhat shorter than that of the cathode terminal 30 as shown in FIG. The convex portion 32 has a convex portion 3
It can be formed by half-etching a flat plate having a length obtained by combining the length of the length 2 and the length of the cathode terminal 30, the width of the cathode terminal 30, and the thickness of the cathode terminal 30.

The end of the cathode terminal 30 where the projection 32 is not formed is located near the end face 22d of the capacitor element 22, for example, slightly outside the end face 22d. End face 22d of lower end 22b of capacitor element 22 than the center
The protrusion 32 is positioned such that the protrusion 32 is located at a position biased to the side.
The end of the cathode terminal 30 on which is formed is disposed. The main surface 22 a of the cathode terminal 30 and the surface of the convex portion 32 on the same surface as the cathode terminal 30 are electrically and mechanically connected to the cathode layer 24 by the conductive adhesive 33.

An anode terminal 34 is arranged below the lower surface 22b of the capacitor element 22 on the side where the end face 22c exists. The anode terminal 34 has a flat plate shape, for example, a rectangular shape having two main surfaces 34a and 34b opposed to each other, and a protrusion 36 similar to the protrusion 32 is formed at one end thereof. The anode terminal 34 has substantially the same thickness as the cathode terminal 30, and the projections 32 and 36 have substantially the same thickness. The end of the anode terminal 34 on the side where the protrusion 36 is not formed is located near the tip of the tantalum wire 26. The protruding portion 36 is slightly larger than the center of the lower surface 22 b of the capacitor element 22 than the end surface 20.
The end of the anode terminal 34 where the protrusion 36 is formed is arranged so as to be located at a certain distance from the protrusion 32 at a position biased toward the c side. The main surface 34b of the anode terminal 34 and the main surface 30b of the cathode terminal 30 are located on the same plane, and the main surfaces 34a and 32a are also located on the same plane.

In order to prevent a portion of the main surface of the anode terminal 34 located below the cathode layer 24 from coming into direct contact with the lower surface of the cathode layer 24, an insulator such as an insulating tape 38 is provided on the main surface. 34b and the main surface of the convex portion 36 on the same plane as the main surface 34b and the cathode layer 24.

The connection between the anode terminal 34 and the tantalum wire 26 is made via a connector, for example, a tantalum wire 40. As shown in FIG. 1B, the tantalum wire 40 is formed in a columnar shape having a width substantially equal to the width of the capacitor element 22, for example, slightly shorter than the width of the capacitor element 22. Are arranged along. The tantalum wire 40 is provided below the tantalum wire 26 on the main surface 34a of the anode terminal 34, and the tantalum wire 26 and the main surface 34a of the anode terminal 34.
a and are electrically and mechanically connected to the tantalum wire 26 and the anode terminal 34 by, for example, welding.

The capacitor element 22 and the tantalum wire 4
0, the cathode terminal 30, and the anode terminal 34 are covered with an exterior resin 42, for example, an epoxy resin. However, although the main surfaces 30b and 34b of the cathode terminal 30 and the anode terminal 34 are exposed from the exterior resin 42, the other surfaces and the projections 3
2 and 36 are buried in the exterior resin 42.

In this chip type tantalum capacitor, the cathode terminal 30 is connected to the cathode layer 24 only on the lower surface 22a of the capacitor element 22. Therefore, unlike the conventional chip type capacitor shown in FIG.
There is no need to insert a cathode terminal inside,
Can be reduced. Moreover, the capacitor element 2
The end of the cathode terminal 30 protrudes only up to the vicinity of the second end face 22c, and the size of the exterior resin 42 can be further reduced.

Similarly to the cathode terminal 30, the anode terminal 34 is located only below the lower surface 22a of the capacitor element 22, and its end protrudes only up to the vicinity of the tip of the tantalum wire 26. The ratio of the exterior resin 42 to the chip type tantalum capacitor 20 can be reduced. Further, since the anode terminal 34 and the protrusion 36 exist not only below the tantalum wire 26 but also on a part of the lower surface 22a of the capacitor element 22, the anode terminal 34
When soldering, a sufficient contact area with the printed circuit board can be secured. Further, since the cathode terminal 30 and the anode terminal 34 exist only below the capacitor element 22, the chip type tantalum capacitor 20 can be downsized. Further, when the chip type tantalum capacitor is formed in the same size as the conventional one, a chip type tantalum capacitor having a larger capacity than the conventional one can be realized.

Further, since the projections 32 and 36 are formed integrally with the cathode terminal 30 and the anode terminal 34, respectively, the contact area with the exterior resin 42 is increased, and
0, the anode terminal 34 is firmly bonded to the exterior resin 42.
In particular, since the protrusions 32 and 36 have a thickness smaller than that of the cathode terminal 30 and the anode terminal 34 and are buried in the exterior resin 42, the protrusions 32 and 36 are the same as the cathode terminal 30 and the anode terminal 34. The contact area with the exterior resin 42 is increased as compared with the case where the thickness is set, and the terminals 30 and 34 are firmly connected to the exterior resin 42. Therefore, even when the terminals 30 and 34 are soldered to the printed circuit board, the exterior resin 42 does not peel off from the terminals.

Further, the cathode terminal 30 and the anode terminal 34
Neither is present on the end face of the exterior resin 42. Therefore,
As shown in FIG. 7B, even when many chip-type tantalum capacitors 20 are mounted side by side on a printed circuit board,
There is no need to attach solder to the side surface of the chip type tantalum capacitor 20. Therefore, the pitch between the chip-type tantalum capacitors 20 can be reduced, and even if the chip-type tantalum capacitors have the same size as the conventional one, the mounting density can be increased. Moreover, as described above, since it is smaller than the conventional one,
More chip type tantalum capacitors can be mounted.

FIGS. 2A and 2B show a chip type tantalum capacitor 20a according to a second embodiment. This chip type tantalum capacitor 20a has the same configuration as the chip type tantalum capacitor 20 shown in FIG. 1 except that the shape of the projection 132 of the cathode terminal 30 is different. The same parts are denoted by the same reference numerals, and description thereof will be omitted.

The projection 132 of the cathode terminal 30 is shown in FIG.
As is clear from FIG. 1, the length dimension is formed longer than the convex portion 32 shown in FIG.
The tip portion is located at a position closer to the end portion 22c than the center portion in the length direction of 2.

Since the length of the projection 132 is increased, the contact area of the cathode terminal 30 with the exterior resin 42 is increased as compared with that of FIG. Strength can be increased. The cathode terminal 30
The length of the convex portion 132 of the anode terminal 34 is increased, but the length of the convex portion 36 of the anode terminal 34 is increased.
2 may be increased in fixing strength.

In the first and second embodiments, the protrusion 3
Although 2, 132 and 36 show rectangular shapes, the present invention is not limited to this, and other polygonal shapes and arc shapes can also be used. Also, the projections 32, 132, 36
Although the thickness is reduced, the thickness may be the same as that of the cathode terminal 30 or the anode terminal 34.

FIGS. 3A to 3C show a chip type tantalum capacitor 20b according to a third embodiment. In the chip type tantalum capacitor 20b, each shape of the cathode terminal 230 and the projection 232 integrated therewith, the anode terminal 234 and the projection 236 integrated therewith is the same as that of the chip type capacitor 20 of the first embodiment. Cathode terminal 30 and integral projection 32, anode terminal 34 and integral projection 3
6, except that the configuration is the same as that of the chip type capacitor 20. The same parts are denoted by the same reference numerals, and description thereof will be omitted.

On both side edges of the cathode terminal 230, a plurality of convex portions 240 and concave portions 242 each having a substantially triangular shape are alternately formed. As shown in FIGS. 7B and 7C, the thickness of the projections 240 is smaller than that of the other portions of the cathode terminal 230. Further, a convex portion 232 is formed in a trapezoidal shape at an inner edge perpendicular to the edge where the convex portion 240 and the concave portion 242 are formed, and is also formed to be thin.

Similarly, a plurality of convex portions 244 and concave portions 246 are alternately formed on both side edges of the anode terminal 234. The protrusion 244 is also formed to be thinner like the protrusion 240. A protrusion 236 is arranged adjacent to the protrusion 232 at an edge perpendicular to the edge where the protrusion 244 and the recess 246 are formed. The length dimension of the protrusion 236 is
32 less than the length dimension. The projections 248 and 2 are also provided on the edge of the cathode terminal 230 and the anode terminal 234 opposite to the edge where the projections 232 and 236 are provided.
50 are provided. These projections 248, 250
It has the same thickness as the cathode terminal 230 and the anode terminal 234.

As described above, in addition to the convex portions 232 and 236, the convex portions 240, 244, 248 and 250, the concave portions 242 and 246
Are formed, and the projections 232, 236, 240, 24
4 has penetrated into the exterior resin 42, so that the cathode terminal 23
0, the anode terminal 234 has a large contact area with the exterior resin 42. As a result, the cathode terminal 230 and the anode terminal 234 are more firmly fixed to the exterior resin 42. Therefore, when the chip type tantalum capacitor 20c is mounted on the printed circuit board, the exterior resin 42
It is difficult to leave from 4. In addition, since the convex portion 232 has a trapezoidal shape, the outer resin 42 is smaller than a rectangular convex portion.
The contact area increases.

FIG. 4 shows a chip type tantalum capacitor 20d according to a fourth embodiment. In this chip type tantalum capacitor 20d, the cathode terminal 230 and the anode terminal 234
The configuration is the same as that of the chip-type tantalum capacitor 20c of the third embodiment except that projections 252 and 254 projecting from both side edges are formed. The same parts are denoted by the same reference numerals, and description thereof will be omitted.

The protrusions 252 and 254 are also formed to be thinner than the cathode terminals 230 and 234 and penetrate into the exterior resin 42. These projections 252 and 254 use a part of a frame used when mass-producing the cathode terminal 230 and the anode terminal 234.

Also in this chip type tantalum capacitor 20d, the contact area of the cathode terminal 230 and the anode terminal 234 with the exterior resin increases, and the fixing strength of both terminals to the exterior resin 42 increases.

In the third and fourth embodiments, the projections 240 and 244 and the recesses 242 and 246 are substantially triangular, but may be other polygons or arcs.
In addition, although the convex portions 240 and 244 and the concave portions 242 and 246 are provided together, only the convex portions 240 and 244 or the concave portions 242 and 242 are provided.
Only 246 may be provided.

FIG. 5 shows a chip type tantalum capacitor 20e according to a fifth embodiment. In this embodiment, the main surfaces 330b and 334 of the cathode terminal 330 and the anode terminal 334 are provided.
A recess is formed on the outer side of b. That is, the main surfaces 330b and 334b are not flat but are formed in irregularities. This increases the contact area of the printed circuit board with the pattern. Also, the main surface 330
b, 334b, the exposed end face of the cathode terminal 330, and the exposed end face of the anode terminal 334, the plating layers 336, 338,
For example, a solder plating layer or a tin plating layer is formed. By forming such plating layers 336 and 338, soldering of the chip-type tantalum capacitor 20e to a printed board or the like can be easily performed, and the solder also rises to the exposed surfaces of the terminals 330 and 334, so that soldering to the board can be performed. The mounting can be performed securely, and the exposed end face can be prevented from being rusted. Furthermore, since the exposed end face is plated, the solder fillet can be easily confirmed. Although the plating layers 336 and 338 are provided, these may be removed in some cases.

In each of the above embodiments, each of the cathode terminal and the anode terminal is provided with a convex portion or a concave portion. However, at least one of the terminals may be provided with a convex portion or a concave portion.

[0039]

As described above, according to the present invention, not only the mounting area can be reduced, but also a desired capacitance can be obtained even if the size is reduced, and the anode terminal and the cathode terminal are formed on the exterior resin. A firmly fixed chip capacitor is obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a chip-type tantalum capacitor according to a first embodiment of the present invention, and a side view and a bottom view in a state where an exterior resin is removed.

FIG. 2 is a vertical sectional view and a bottom view of a chip type tantalum capacitor according to a second embodiment of the present invention.

FIG. 3 is a bottom view of a chip type tantalum capacitor according to a third embodiment of the present invention, a front view of a cathode terminal and an anode terminal used in the capacitor, and a side view of the cathode terminal.

FIG. 4 is a bottom view of a chip-type tantalum capacitor according to a fourth embodiment of the present invention.

FIG. 5 is a vertical sectional view of a chip-type tantalum capacitor according to a fifth embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a conventional chip type tantalum capacitor.

FIG. 7 is a diagram showing a ten-manic state of the chip-type tantalum capacitors of FIGS. 6 and 1;

[Explanation of symbols]

 Reference Signs List 20 chip-type tantalum capacitor 22 capacitor element 24 cathode layer 26 anode lead 30 cathode terminal 32 projection 34 anode terminal 36 projection

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Okada 3-53-3 Senaricho, Toyonaka City, Osaka Inside Matsuo Electric Co., Ltd. (72) Inventor Toyoshi 3-5 Senaricho, Toyonaka City, Osaka No. 3 Matsuo Electric Co., Ltd.

Claims (4)

[Claims] 1. A capacitor element having a cathode layer having at least one flat surface on an outer surface of a main body, and an anode lead body protruding outward from one end of the main body. A first main surface is located below and parallel to the plane of the cathode layer, and the first main surface is electrically connected to the plane of the cathode layer. And a flat cathode terminal connected to the first and second main surfaces. The third main surface is located substantially in the same plane as the first main surface. And a plate-shaped anode terminal having a third main surface electrically connected thereto, and exposing at least a part of second and fourth main surfaces of the anode terminal and the cathode terminal to form the capacitor element, An exterior resin covering the anode terminal and the cathode terminal; and the anode terminal and the cathode terminal. A chip capacitor characterized in that at least one of the components has a contact area increasing portion formed at a contact portion with the exterior resin. 2. The chip capacitor according to claim 1, wherein said contact area increasing portion is formed in a convex portion and penetrates into said exterior resin. 3. The chip capacitor according to claim 1, wherein the contact area increasing portion is formed in a concave portion, and the exterior resin enters the concave portion. 4. The chip capacitor according to claim 1, wherein the contact area increasing portion is formed in an uneven portion, the projecting portion enters the exterior resin, and the exterior resin enters the concave portion. A chip capacitor.