JP3240009U - case for capacitor - Google Patents

Abstract

A capacitor case capable of suppressing swelling of the top surface portion during reflow without thickening a base material plate (particularly, a base material plate forming the top surface portion) is provided. Kind Code: A1 In a capacitor case 1 having a tubular portion 10 having a tubular shape and a top surface portion 20 closing one end of the tubular portion 10, the R dimension of a corner portion 22 of the top surface portion 20 is 0. It is larger than 0.5 mm and not more than three times the thickness of the top surface portion 20 . [Selection drawing] Fig. 1

Description

The present invention relates to a capacitor case.

2. Description of the Related Art Conventionally, a capacitor case having a cylindrical portion and a top portion closing one end of the cylindrical portion is widely known (see, for example, Patent Document 1). A capacitor can be manufactured by enclosing a capacitor element, an electrolytic solution, and the like in such a capacitor case.

Japanese Patent Application Laid-Open No. 2003-309047

By the way, as a method of mounting an electronic component such as a capacitor on a substrate, surface mounting is generally practiced. In surface mounting, reflow is used to fix electronic components with solder, but in recent years lead-free solder with a high melting point has come to be used from the viewpoint of environmental considerations, etc., and the temperature during reflow has to be raised. There is a circumstance that there is no

When the temperature during reflow rises, the internal pressure rises temporarily due to vaporization of the electrolyte inside the capacitor, and the top surface of the capacitor case may swell. A capacitor with a bulging top surface gives the consumer the impression that it is a defective product, even if there is no problem in performance or safety. Further, if the swelling of the top surface of the capacitor case causes the internal capacitor element to move significantly, it may lead to a short circuit. Therefore, in the technical field of capacitors, it is required to reduce swelling of the top surface of the capacitor case.

In order to suppress swelling of the top surface portion, it is conceivable to increase the strength of the capacitor case by increasing the thickness of the base material plate (particularly, the base material plate forming the top surface portion). However, increasing the thickness of the base plate causes new problems such as an increase in cost and a decrease in the storage area inside the case (a decrease in the capacitance value that can be achieved when used as a capacitor).

The present invention has been made in view of the above problems, and is a capacitor capable of suppressing swelling of the top surface during reflow without thickening the base material plate (particularly, the base material plate that constitutes the top surface). The purpose is to provide a case for

A capacitor case according to the present invention is a capacitor case having a tubular portion having a tubular shape and a top surface portion closing one end of the tubular portion, wherein the corner portion of the top surface portion has an R dimension of , larger than 0.5 mm, and three times or less the thickness of the top surface portion.

In the capacitor case of the present invention, since the R dimension of the corners of the top surface portion is larger than 0.5 mm, the top surface portion can be easily reflowed even if the base material plate is not thickened, as shown in Examples described later. Swelling can be suppressed.

In the conventional capacitor case, the R dimension of the corner portion of the top surface was set to 0.5 mm or less regardless of the size of the capacitor case. The reason for this is that conventionally, no attention has been paid to the element of "R dimension of the corner portion of the top surface", and an appropriate numerical value has been used.

It is a figure shown in order to demonstrate the case 1 for capacitor|condenser which concerns on embodiment. 4 is a graph showing test results in Example 1. FIG. It is a graph which shows the result of the test in a comparative example. 4 is a graph showing test results in Example 2. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION A capacitor case according to the present invention will be described below based on an embodiment shown in the drawings. Each drawing is a schematic diagram and does not necessarily strictly reflect the actual structure or configuration. The embodiments described below do not limit the inventions claimed in the utility model registration claims. Also, not all elements and combinations thereof described in the embodiments are essential to the present invention.

[Embodiment]
FIG. 1 is a diagram for explaining a capacitor case 1 according to an embodiment. 1(a) is a plan view of the capacitor case 1, FIG. 1(b) is a front view of the capacitor case 1, and FIG. 1(c) is a cross-sectional view taken along line AA of FIG. be. In FIG. 1, illustration of structural elements and structures that are less relevant to the present invention is omitted. Examples of such structural elements and structures include resin coatings and concave-convex structures in cylindrical portions, and descriptions thereof are also omitted.

1. Capacitor case 1
As shown in FIG. 1 , the capacitor case 1 according to the embodiment has a tubular portion 10 having a tubular shape and a top surface portion 20 closing one end of the tubular portion 10 . As a material constituting the capacitor case 1, a known suitable metal material such as aluminum or an aluminum alloy can be used.

In the capacitor case 1 , the R dimension of the corner portion 22 of the top surface portion 20 is larger than 0.5 mm and not more than three times the thickness of the top surface portion 20 . In the capacitor case 1, the R dimension is preferably 0.65 mm or more.

In this specification, the term "corner of the top surface" refers to the outer peripheral portion of the top surface. Further, the "R dimension of the corner" in this specification represents the degree of roundness of the corner on the outer surface of the capacitor case. Further, the term "base material plate" in this specification refers to a metal plate that constitutes the capacitor case. In this specification, the "thickness of the top surface" refers to the average value of the thickness of the top surface. The reduced amount is not included in the calculation. That is, when judging whether the R dimension of the corners of the top surface is three times or less the thickness of the top surface, the thickness of the top surface is calculated assuming that there is no explosion-proof groove.

An explosion-proof groove 24 is formed in the top surface portion 20 of the capacitor case 1 . The explosion-proof groove 24 consists of a plurality of grooves that are joined together. In the capacitor case 1 , three grooves forming the plurality of grooves are radially formed, and one end of each groove is connected at the center of the top surface portion 20 in a plan view. The explosion-proof groove 24 in the capacitor case 1 is formed on the inner surface side of the top surface portion 20 (on the side where the capacitor element is inserted).

In a capacitor case having an explosion-proof groove such as the capacitor case 1, in order to suppress swelling of the top surface, the strength (valve strength) at which the explosion-proof groove splits (the top surface operates as an explosion-proof valve) is adjusted. It is also conceivable to suppress a decrease in the strength of the top surface portion by increasing the height. However, as shown in Example 2, which will be described later, even if the strength of the valve is increased, the effect is smaller than when the R dimension of the corner portion of the top surface portion is increased. On the other hand, if the strength of the valve is too high, the explosion-proof groove will not split when necessary (the explosion-proof valve will not operate).

The capacitor case 1 according to the embodiment can be manufactured, for example, by drawing a plate material to form the tubular portion 10 and the top surface portion 20, and then forming the explosion-proof groove 24 in the top surface portion 20. A known method can be used for drawing. The explosion-proof grooves 24 are formed by any processing method capable of forming grooves in metal materials, such as processing using a mold (sheet metal processing), processing using a cutting tool (machine processing), electric discharge machining, etching, etc. can be formed.

2. Effects of the Capacitor Case 1 According to the Embodiment In the capacitor case 1 according to the embodiment, since the R dimension of the corner portion 22 of the top surface portion 20 is larger than 0.5 mm, even if the base material plate is not thickened, the capacitor case 1 can be easily reflowed during reflow. It is possible to suppress the swelling of the top surface portion 20 in .

By the way, as shown in Examples 1 and 2 which will be described later, basically, the larger the R dimension of the corner portion 22 of the top surface portion 20, the smaller the swelling of the top surface portion 20 becomes. However, as the radius R of the corners 22 of the top surface 20 increases, the internal storage area becomes smaller, and the inner surface of the corners 22 presses and stresses the capacitor element. On the other hand, according to the capacitor case 1 according to the embodiment, since the R dimension of the corner portion 22 of the top surface portion 20 is three times or less the thickness of the top surface portion 20, by setting the R dimension as the upper limit, the internal It is possible to prevent the storage area from becoming too small, and it is also possible to suppress pressure on the capacitor element by the inner surface of the corner portion 22 to such an extent that it does not pose a problem.

Further, according to the capacitor case 1 according to the embodiment, when the R dimension is 0.65 mm or more, it is possible to further suppress swelling of the top surface portion 20 during reflow.

Further, according to the capacitor case 1 according to the embodiment, since the explosion-proof groove 24 is formed in the top surface portion 20, the top surface portion 20 can be used as an explosion-proof valve. It is possible to prevent the capacitor from exploding due to an increase in internal pressure, or to reduce the intensity of the explosion.

[Example 1]
2 is a graph showing the results of the test in Example 1. FIG. The circular mark for each sample in FIG. 2 is the average value of swelling of the top surface portion, and the upper and lower lines indicate the maximum and minimum values. The circles and the lines above and below the circles are the same in FIGS. 3 and 4, which will be described later.

In Example 1, as a capacitor case according to the present invention, a capacitor case (hereinafter referred to as sample 1) having a diameter of the cylindrical portion of 10 mm and an R dimension of the corner portion of the top surface portion of 0.65 mm was used. ), and a capacitor case (hereinafter referred to as sample 2) having a cylindrical portion with a diameter of 10 mm and a corner portion of the top surface with an R dimension of 0.8 mm. As a capacitor case for comparison, a capacitor case (a capacitor case corresponding to a conventional product) having a diameter of a cylindrical portion of 10 mm and an R dimension of a corner portion of a top surface portion of 0.5 mm was used. Hereinafter, referred to as comparative sample 1) was also prepared. The thickness of the top surface of each sample was 0.33 mm. The number of each sample was 10, respectively. The explosion-proof grooves as described in the embodiment were formed in the top surface of each sample, and the valve strength was set to 3.3 MPa.

Next, capacitors were produced using the capacitor case described above, and their total lengths were measured. After that, each capacitor was heat-treated twice with a peak temperature of 250° C., a time of 217° C. or higher for 90 seconds, and a time of 245° C. or higher for 30 seconds. After confirming that the capacitors were sufficiently cooled after the heat treatment, the total length of each capacitor was measured again, and the difference from the total length before the heat treatment was taken as the swelling of the top surface.

As a result, as shown in FIG. 2, it was confirmed that Samples 1 and 2 had smaller swelling of the top surface portion than Comparative Sample 1 did. In a capacitor case having a cylindrical portion with a diameter of 10 mm, the bulge of the top surface portion is set to 0.4 mm from the viewpoint of appearance without problems and from the viewpoint of sufficiently suppressing the occurrence of short circuits caused by movement of the capacitor element. It is considered preferable to: Samples 1 and 2 had both the average value and the maximum value of swelling of the top surface portion of less than 0.4 mm. It was also confirmed that sample 2, which has a larger R dimension at the corners than sample 1, has a smaller bulge at the top surface.

[Comparative example]
FIG. 3 is a graph showing test results in a comparative example.
In the comparative example, the difference in swelling of the top surface portion was confirmed when the valve strength of the top surface portion was changed. In the comparative example, capacitor cases each having a cylindrical portion with a diameter of 10 mm and a corner portion of the top surface having an R dimension of 0.5 mm and having different valve strengths were prepared. Specifically, a capacitor case with a valve strength of 3.3 MPa (a capacitor case corresponding to a conventional product; hereinafter referred to as Comparative Sample 2) and a capacitor case with a valve strength of 3.6 MPa (hereinafter referred to as a comparative sample 2). A capacitor case having a valve strength of 4.0 MPa (hereinafter referred to as a comparative sample 4) was prepared. The thickness of the top surface of each sample was 0.33 mm. The number of each sample was 10, respectively.

A capacitor was produced using the prepared capacitor case, and under the same conditions as in Example 1, the total length was measured and heat treatment was performed. As a result, as shown in FIG. 3, in Comparative Sample 2, the average value of swelling of the top surface portion was about 0.4 mm, and in Comparative Samples 3 and 4, the average value of swelling of the top surface portion was 0.4 mm or less. However, in all of Comparative Samples 2, 3, and 4, the maximum value of swelling of the top surface portion was 0.4 mm or more. From the results of the comparative example, although there is a tendency for the swelling of the top surface to decrease as the valve strength increases, the effect is smaller than when the R dimension of the corner of the top surface is increased (compared to the risk of concern). It was confirmed that the effect obtained by

[Example 2]
4 is a graph showing the results of the test in Example 2. FIG.
In Example 2, a capacitor case having a diameter different from that of Example 1 was prepared. In Example 2, as a capacitor case according to the present invention, a capacitor case (hereinafter referred to as sample 3) having a diameter of a cylindrical portion of 18 mm and an R dimension of a corner portion of a top surface portion of 0.75 mm was used. ), and a capacitor case (hereinafter referred to as sample 4) having a diameter of the cylindrical portion of 18 mm and an R dimension of the corner portion of the top surface portion of 1.0 mm. As a capacitor case for comparison, a capacitor case (a capacitor case corresponding to a conventional product) having a cylindrical portion with a diameter of 18 mm and an R dimension of the corner portion of the top surface portion of 0.5 mm was used. Hereinafter, referred to as comparative sample 5.) was also prepared. The thickness of the top surface of each sample was 0.42 mm. The number of each sample was 10, respectively. The explosion-proof groove as described in the embodiment was formed on the top surface of each sample, and the valve strength was set to 1.6 MPa.

A capacitor was manufactured using the prepared capacitor case, and under the same conditions as in Example 1, the total length was measured and heat treatment was performed. As a result, as shown in FIG. 4, it was confirmed that Samples 3 and 4 had a smaller swelling of the top surface than Comparative Sample 5 did. In a capacitor case with a cylindrical portion having a diameter of 18 mm, the bulge of the top surface portion is set to 0.75 mm from the viewpoint of appearance without problems and from the viewpoint of sufficiently suppressing the occurrence of short circuits caused by movement of the capacitor element. It is considered preferable to: In samples 3 and 4, both the average value and the maximum value of swelling of the top surface portion were less than 0.75 mm. It was also confirmed that sample 4, which has a larger R dimension at the corners than sample 3, has a smaller swelling of the top surface.

Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments. It can be implemented in various aspects without departing from the spirit thereof, and for example, the following modifications are also possible.

(1) The shapes and the like of the constituent elements described in the above embodiments are examples, and can be changed within the scope that does not impair the effects of the present invention.

(2) For example, the explosion-proof groove 24 in the above embodiment is an example, and the length, depth, arrangement, cross-sectional shape, etc. of the grooves constituting the explosion-proof groove are not limited to those described in the embodiment.

(3) In the capacitor case of the present invention, the explosion-proof groove may be formed on the outer surface side of the top surface.

(4) In the capacitor case of the present invention, the explosion-proof groove may not be formed on the top surface.

DESCRIPTION OF SYMBOLS 1... Capacitor case 10... Cylindrical part 20... Top surface part 22... Corner part 24... Explosion-proof groove

Claims (3)

A capacitor case having a tubular portion having a tubular shape and a top surface portion closing one end of the tubular portion,
A capacitor case according to claim 1, characterized in that the R dimension of the corners of the top surface is larger than 0.5 mm and not more than three times the thickness of the top surface. 2. The capacitor case according to claim 1, wherein said R dimension is 0.65 mm or more. 3. The capacitor case according to claim 1, wherein an explosion-proof groove is formed in the top surface.

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