JP2023025983A - Electrolytic capacitor and circuit board - Google Patents

Abstract

To enable a mounting of an electrolytic capacitor 1 so as to be prevented from being inclined on a circuit board.SOLUTION: An electrolytic capacitor 1 comprises: a capacitor main body forming a cylinder shape; and a synthetic resin pedestal 4 having a square bottom surface 11a attached to one end part of the capacitor main body. A positive electrode terminal 16A and a negative electrode terminal 16B are provided to the bottom surface 11a, and the electrolytic capacitor 1 is mounted in a standing posture by soldering each of them to a land part of the circuit board. The terminals 16A and 16B comprise a convex part 15 that is positioned in a corner part of both sides of one side 11b of the bottom surface 11a, and becomes an auxiliary projection in an intermediate part in the opposite side 11c. A posture of the electrolytic capacitor 1 becomes stable because it is supported by three points forming a peak point of a triangle.SELECTED DRAWING: Figure 3

Description

The present invention relates to an electrolytic capacitor provided with a synthetic resin base and a circuit board to which this electrolytic capacitor is attached.

Electrolytic capacitors, typified by aluminum electrolytic capacitors, generally have a configuration in which an anode foil and a cathode foil made of metal foil such as aluminum are wound together with insulating paper and impregnated with an electrolytic solution. In Patent Documents 1 and 2, a pedestal made of synthetic resin is provided at one end of a cylindrical capacitor main body, and the central axis of the cylinder is surface-mounted on a circuit board in a mounting posture perpendicular to the surface of the circuit board. Disclosed is an electrolytic capacitor that enables

In an electrolytic capacitor with such a pedestal, as disclosed in Patent Documents 1 and 2, a pair of (strictly positive and negative) terminals are provided on the rectangular bottom surface of the pedestal. These terminals are formed by bending the tip of a metal member extending from the capacitor body through the pedestal into a substantially L shape, and extend in opposite directions along the radial direction of the cylinder.

JP-A-11-233384 JP-A-59-211214

An electrolytic capacitor with a pedestal as described above is supported on a circuit board by soldering two terminals to the lands of the circuit board using a suitable soldering technique such as reflow soldering. In many cases, the terminal formed by bending the leading end of the metal member protrudes slightly from the bottom surface of the base made of synthetic resin. Therefore, when the electrolytic capacitor is set on the circuit board for soldering, the posture of the electrolytic capacitor is unstable, and the electrolytic capacitor may be soldered onto the circuit board in an inclined posture.

Further, when an electrolytic capacitor is used in a place where a vibration input is always applied, such as an electronic device for a vehicle, the electrolytic capacitor is likely to vibrate.

One aspect of the present invention is an electrolytic capacitor comprising a capacitor body having a cylindrical case and a synthetic resin base having a square bottom surface attached to an end of the capacitor body. hand,
Positive and negative terminals protruding from the bottom surface of the pedestal are provided so as to be in local contact with the mounting surface, and these two terminals extend along the central axis of the cylindrical capacitor body. within 180° of the center,
Within the remaining 180° range, one auxiliary projection protruding from the bottom surface is provided so as to be in local contact with the mounting surface,
The central axis is included in a triangular region formed by three points of the two terminals and the auxiliary projection.

According to this invention, since the capacitor is supported at three vertices of a triangle including the central axis of the capacitor body, the electrolytic capacitor can be soldered onto the circuit board in a stable posture. Vibration of the electrolytic capacitor is less likely to occur even with vibration input from the outside.

1 is a perspective view of an electrolytic capacitor of one embodiment; FIG. 1 is a perspective view of an electrolytic capacitor with a part cut away; FIG. FIG. 4 is a bottom view showing the arrangement of terminals in the first embodiment; The front view of 1st Example. Explanatory drawing seen from the bottom surface showing the positional relationship with the center of gravity. The front view which showed the positional relationship with the center of gravity. The bottom view which shows arrangement|positioning of the terminal of 2nd Example. The front view of 2nd Example. Explanatory drawing seen from the bottom surface showing the positional relationship with the center of gravity. The front view which showed the positional relationship with the center of gravity. The bottom view which shows arrangement|positioning of the terminal of 3rd Example. The front view of 3rd Example. The top view of the terminal which provided the boss|hub part. FIG. 4 is a cross-sectional view of a portion where a terminal provided with a boss portion is soldered to a circuit board;

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing the overall structure of an electrolytic capacitor 1 according to an embodiment of the invention, and FIG. 2 is a partially cut-away perspective view showing the internal structure. The electrolytic capacitor 1 of this embodiment is, for example, a so-called aluminum electrolytic capacitor used in electronic devices that serve as various controllers for automobiles. and a synthetic resin pedestal 4 attached to one end of the capacitor body 2 .

As shown in FIG. 2, the capacitor body 2 has a general structure in which an internal element 5 is housed in a case 3. The internal element 5 is made by winding an anode foil and a cathode foil made of aluminum foil together with insulating paper and impregnating them with an electrolytic solution. The case 3 is sealed by inserting a sealing material 6 made of synthetic rubber into the opening of the case 3 and crimping the end of the case 3 inward. By this caulking process, the concave groove portion 7 at the end of the case 3 is formed over the entire circumference. Strip-shaped metal plates 8 serving as electrodes are connected to the ends of the wound anode foil and cathode foil, respectively. It is led out to the outside of the main body 2 . Note that the internal structure of the capacitor body 2 is not an essential part of the present invention, and therefore any known structure may be used.

The pedestal 4 is integrally formed of hard synthetic resin as a whole, and as shown in FIG. and a total of four support pieces 12 provided on each of them. The four support pieces 12 are arranged so as to surround the cylindrical capacitor body 2 as a whole. It has a ridge portion 12a that engages with the concave groove portion 7 of the housing. Therefore, by pressing the capacitor body 2 into the pedestal 4 so that the cylindrical case 3 fits inside the four support pieces 12, the elastic deformation of the support pieces 12 causes the capacitor body 2 and the pedestal 4 to move. are assembled together. Then, the ridges 12a are engaged with the recessed grooves 7 to prevent them from slipping off. The strip-shaped metal plate 8, which serves as the electrode of the internal element 5, is further passed through the seat portion 11 and is bent into a substantially L-shape to form a terminal, which will be described later.

When combined with the pedestal 4 , the cylindrical capacitor main body 2 assumes a posture in which the central axis L (see FIG. 4 ) is perpendicular to the plate-like seat portion 11 . Therefore, by fixing the pedestal 4 to a circuit board or the like as will be described later, the capacitor body 2 is mounted in a posture orthogonal to the surface of the circuit board or the like (in other words, an upright posture).

In the illustrated example, two adjacent corners among the four corners of the pedestal 4 are obliquely cut off as tapered portions 13 . Therefore, the two support pieces 12 corresponding to the tapered portion 13 are thinner in radial dimension than the other two support pieces 12, but there is no difference in basic function.

Next, the essential part of the first embodiment will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 shows the bottom surface 11a of the seat portion 11 of the base 4. As shown in FIG. The bottom surface 11a is basically flat except for one projection 15 that serves as an auxiliary projection. Two terminals 16 (a positive electrode terminal 16A and a negative electrode terminal 16B) are arranged on the bottom surface 11a by bending the ends of the strip-shaped metal plate 8 along the bottom surface 11a. These terminals 16 are obtained by bending the end portions of the strip-shaped metal plate 8 led out from the bottom surface 11 toward the outer peripheral side, and are rectangular in plan view as shown in FIG. Also, basically, the two terminals 16 have similar dimensions.

In the first embodiment, a positive terminal 16A and a negative terminal 16B are arranged at the corners on both sides of one side (indicated by reference numeral 11b) of the bottom surface 11a, and extend along a direction perpendicular to the side 11b. , and parallel to each other. These terminals 16A and 16B are located near the outer periphery of the cylindrical capacitor body 2 and are spaced apart from each other so that the distance along the side 11b between the two terminals 16A and 16B is as large as possible. there is

In the illustrated example, the positive terminal 16A is arranged at the corner having the tapered portion 13, and the negative terminal 16B is arranged at the right-angled corner. In other words, the positive/negative polarity can be easily identified by the positional relationship with the tapered portion 13 on the pedestal 4 .

The projection 15 serving as an auxiliary projection is formed integrally with the base 4 made of synthetic resin as part of the base 4, and as is clear from FIGS. It is cylindrical or disk-shaped with a height equal to the volume. As shown in FIG. 3, the convex portion 15 is located in the middle portion of the side 11c facing the side 11b on which the terminal 16 is arranged. More specifically, it is arranged at a position intermediate the distance between the two terminals 16 so as to form an isosceles triangle together with the two terminals 16 .

The two terminals 16A and 16B and the convex portion 15 arranged in this manner locally come into contact with the surface of the circuit board, which is the mounting surface, when the electrolytic capacitor 1 is mounted on the circuit board. That is, the electrolytic capacitor 1 is supported by three points located at the vertices of the triangle, and can be mounted on the circuit board in an upright posture.

5 and 6 are explanatory diagrams for explaining in more detail the positional relationship between the terminals 16A, 16B and the projection 15 of the first embodiment. FIG. 6 shows the circuit board 21 together with the electrolytic capacitor 1. there is

Line L in FIG. 6 indicates the central axis of the cylindrical capacitor body 2 . The center of gravity G of the capacitor body 2 is on this central axis line L. As shown in FIG. Line M1 in FIG. 5 is a line that intersects central axis L and is parallel to sides 11b and 11c, and line M2 is a line that intersects central axis L and is orthogonal to line M1. Lines M1 and M2 are lines that bisect the bottom surface 11a, and the intersection of the two (the point on the central axis L) is the center of the rectangle when the bottom surface 11a is regarded as a rectangle without the tapered portion 13. approximately equivalent to

As shown in FIG. 5, the two terminals 16A and 16B on the bottom surface 11a are located on one side of the line M1, that is, within a range of 180° around the center axis L, and the protrusion 15 is located on the line M1. within the remaining 180°. The central axis L is included in the area of the triangle TR formed by the two terminals 16A and 16B and the convex portion 15. As shown in FIG. Therefore, when the electrolytic capacitor 1 is erected on the circuit board 21 as shown in FIG. 6, the center of gravity G is always within the area of the triangle TR.

Due to such a relationship, when the electrolytic capacitor 1 is soldered onto the circuit board 21, the electrolytic capacitor 1 is less likely to be tilted, and can be mounted in a correctly upright state with respect to the circuit board 21. - 特許庁Further, even if the electronic device for a vehicle or the like receives external vibrations, the electrolytic capacitor 1 is widely supported at three points, so that the electrolytic capacitor 1 does not vibrate and fall off the circuit board 21 . In particular, since the central axis L of the capacitor body 2 corresponding to the center of gravity G is located in the center of the triangle TR forming the isosceles triangle, the electrolytic capacitor 1 is less likely to tilt regardless of the direction of external force.

Next, the essential part of the second embodiment will be described with reference to FIGS. 7 and 8. FIG. In the second embodiment, dummy terminals 23 are provided as auxiliary projections instead of the projections 15 described above. The positions and configurations of the positive terminal 16A and the negative terminal 16B are the same as in the first embodiment described above, and are arranged at the corners on both sides of one side 11b of the bottom surface 11a of the base 4, respectively. The dummy terminal 23 is arranged in the middle of the side 11c facing the side 11b, and has a rectangular shape that intersects the side 11c. The dummy terminal 23 is a terminal-shaped metal piece that is not electrically connected to the capacitor main body 2. For example, a metal member bent into an L shape is molded on the base 4, or is formed on the flat bottom surface 11a. It can be formed by an appropriate method such as printing. The thickness of the dummy terminal 23 (the amount of protrusion from the bottom surface 11a) is basically equal to the amount of protrusion from the bottom surface 11a of the two terminals 16A and 16B.

The positive/negative terminals 16A and 16B and the dummy terminal 23 arranged in this manner locally come into contact with the surface of the circuit board, which is the mounting surface, when the electrolytic capacitor 1 is mounted on the circuit board. That is, the electrolytic capacitor 1 is supported by three points located at the vertices of the triangle, and can be mounted on the circuit board in an upright posture.

9 and 10 are explanatory diagrams for explaining in more detail the positional relationship between the terminals 16A and 16B and the dummy terminal 23 of the second embodiment, and these diagrams correspond to FIGS. 5 and 6 described above. there is Also in the configuration of the second embodiment, the two terminals 16A and the dummy terminal 23 are positioned at the vertices of an isosceles triangle TR. located in the center of

Therefore, when the electrolytic capacitor 1 is soldered onto the circuit board 21, the electrolytic capacitor 1 is less likely to be tilted, and can be mounted in a state of being properly upright with respect to the circuit board 21. - 特許庁Further, even if the electronic device for a vehicle or the like receives external vibrations, the electrolytic capacitor 1 is widely supported at three points, so that the electrolytic capacitor 1 does not vibrate and fall off the circuit board 21 . In particular, since the central axis L of the capacitor body 2 corresponding to the center of gravity G is located in the center of the triangle TR forming the isosceles triangle, the electrolytic capacitor 1 is less likely to tilt regardless of the direction of external force.

In the second embodiment, preferably, the circuit board 21 is provided with dummy land portions corresponding to the dummy terminals 23, and the dummy terminals 23 are soldered to the dummy land portions. That is, when the electrolytic capacitor 1 is mounted on the circuit board 21 using a technique such as reflow soldering, the positive terminal 16A and the negative terminal 16B are soldered to two lands that are part of the circuit of the circuit board 21. A dummy terminal 23 is soldered to a dummy land portion that does not constitute a circuit. In such a configuration, the electrolytic capacitor 1 is soldered to the circuit board 21 at three points forming the triangle TR, and is supported more firmly.

Next, the essential part of the third embodiment will be described with reference to FIGS. 11 and 12. FIG. In the third embodiment, as is clear from FIG. 11, the directions of the positive terminal 16A and the negative terminal 16B (the direction in which the rectangular terminals 16A and 16B extend) are different from those in the first and second embodiments. The terminal 16 is oriented along the winding direction of the aluminum foil (anode foil and cathode foil) in the internal element 5 of the capacitor body 2. The positive electrode terminal 16A located at the corner having the tapered portion 13 extends in a direction intersecting the side 11b, and the negative electrode terminal 16B located at the right-angled sharp corner extends along the side. It extends in a direction parallel to 11b. That is, the two terminals 16A and 16B extend in directions different from each other by 90°. In such a configuration, the terminals 16A and 16B can be configured by simply bending the ends of the strip metal plate 8 connected to the anode foil and the cathode foil into an L shape, and the strip metal plate 8, the anode foil and the cathode foil can be formed. The connection structure with is not complicated.

Although the illustrated third embodiment has dummy terminals 23 similar to those of the second embodiment as auxiliary projections, it is possible to combine them with the projections 15 similar to those of the first embodiment.

13 and 14 show modifications of the terminals 16 (positive terminal 16A and negative terminal 16B). As described above, the terminal 16 is exposed in a rectangular plate shape by bending the ends of the strip-shaped metal plate 8. A part of the terminal 16 has a mounting surface (that is, a land surface of the circuit board 21). ) is formed. In the illustrated example, the boss portion 25 protrudes from the surface of the terminal 16 so as to form a substantially hemispherical shape. Note that the shape of the boss portion 25 may be other shapes, such as a truncated cone shape, a conical shape, and the like.

By providing the boss portion 25 in this manner, the terminal 16 does not come into surface contact with the land surface, but is in a form close to point contact. Therefore, it becomes easy to manage dimensions so that the auxiliary projections (projections 15 and dummy terminals 23) have the same height. Further, by contacting the boss portion 25 with the land surface, as shown in FIG. 14, an appropriate gap is secured between the surface of the terminal 16 and the land surface. attached. Therefore, it is advantageous in terms of soldering stability.

A similar boss portion may be formed on the dummy terminal 23 as well.

Although several embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible. For example, the mounting structure of the pedestal 4 with respect to the capacitor body 2 is not limited to the fitting structure using the support pieces 12 described above, and any mounting structure may be used. Also, the tapered portion 13 of the base 4 is not essential, and a simple rectangular base may be used. Also, the relationship between the terminal 16 and the capacitor body 2 may be different from the above embodiment.

DESCRIPTION OF SYMBOLS 1... Electrolytic capacitor 2... Capacitor main body 3... Case 4... Base 8... Strip metal plate 11... Seat part 11a... Bottom surface 12... Support piece 15... Convex part 16... Terminal 16A... Positive electrode Terminal 16B Negative terminal 21 Circuit board 23 Dummy terminal 25 Boss portion L Central axis G Center of gravity TR Triangle.

Claims (9)

An electrolytic capacitor comprising a capacitor body having a cylindrical case and a synthetic resin pedestal having a square bottom surface attached to an end of the capacitor body,
Positive and negative terminals protruding from the bottom surface of the pedestal are provided so as to be in local contact with the mounting surface, and these two terminals extend along the central axis of the cylindrical capacitor body. within 180° of the center,
Within the remaining 180° range, one auxiliary projection protruding from the bottom surface is provided so as to be in local contact with the mounting surface,
The central axis is included in a triangular region formed by three points of the two terminals and the auxiliary projection,
Electrolytic capacitor. The positive and negative terminals are respectively arranged at the corners on both sides of one side of the bottom surface,
The auxiliary projection is arranged in the middle part of another side opposite to the side,
The electrolytic capacitor according to claim 1. Each terminal is formed by bending an end of a strip-shaped metal plate connected to an end of a metal foil wound with insulating paper into a substantially L shape so as to expand outward,
The two terminals extend in directions different from each other by 90° along the winding direction of each metal foil.
3. The electrolytic capacitor according to claim 1 or 2. The two terminals are located at corners on both sides of one side of the bottom surface and extend in directions parallel to each other.
3. The electrolytic capacitor according to claim 1 or 2. each of the terminals has a plate shape extending along the bottom surface;
A boss portion protruding toward the mounting surface is formed on a part of the terminal,
The electrolytic capacitor according to any one of claims 1 to 4. The auxiliary projection is a dummy terminal that is not electrically connected to the capacitor body,
The electrolytic capacitor according to any one of claims 1 to 5. The auxiliary projection is a projection integrally formed with the pedestal,
The electrolytic capacitor according to any one of claims 1 to 5. In the pedestal, two adjacent corners among the four corners are obliquely cut off as tapered parts,
Among the two positive and negative terminals, the positive terminal is located relatively close to the tapered portion, and the negative terminal is relatively distant from the tapered portion.
The electrolytic capacitor according to any one of claims 1-7. A circuit board to which the electrolytic capacitor according to claim 6 is attached,
The above positive and negative terminals are soldered to the land part that is part of the circuit,
A circuit board, wherein the dummy terminal is soldered to a dummy land portion that does not form a circuit.

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