JPH088148A - Electrolytic capacitor and manufacturing method - Google Patents

Abstract

PURPOSE:To make it possible to estimate a life of an electrolytic capacitor easily and surely by storing an inner capacitor element in a case that can be confirmed visually from outside. CONSTITUTION:In an electrolytic capacitor, a capacitor element 1 impregnated with electrolytic solution is stored in a tightly sealed state in a storage case (A) made of a resin case 5 joined with a metallic case 6. The cylindrical metallic case 6 on one opened end has a step part with an engagement part. The metallic case 6 is molded in a body with the cylindrical resin case 5 with a bottom in a way that this step part is embedded in an opened end of the transparent resin case 5. Since the resin case 5 is transparent, the capacitor element in the storage case can be visually observed from outside. In addition, the storage case is tightly sealed in a one-body molding step and a deterioration of the capacitor element caused by outside air can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor whose life can be easily predicted by visually confirming deterioration over time due to use, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, electronic parts have been required to have smaller size, higher performance and improved reliability. The same applies to the electrolytic capacitor incorporated in the device and used.

Generally, in an electrolytic capacitor, a pair of lead terminals also made of aluminum are connected to a pair of anode foil and cathode foil made of high-purity aluminum foil, and a capacitor paper is provided between the pair of anode foil and cathode foil. It uses a capacitor element formed by interposing. The surface of this capacitor element is electrochemically roughened in order to increase the surface area of the aluminum anode foil / cathode foil. Furthermore, a dielectric oxide film is formed on the anode foil.

As an electrolytic capacitor using such a capacitor element, for example, there is one as shown in FIG. That is, the capacitor element 21 is housed in the housing case 25 made of a cylindrical metal that is impregnated with the driving electrolytic solution and has an opening on one side. The sealing plate 23, which is a sealing member for the opening of the housing case 25, is provided with a rivet portion 24. The lead-out terminal 22 of the capacitor element 21 is connected to the rivet portion 24 of the sealing plate 23, and the sealing plate 23 is bite into the opening of the housing case 25 to seal it. In the electrolytic capacitor configured as described above, by sealing the housing case 25, the capacitor element 2 is shielded from the outside air to be protected from moisture.
1 and the driving electrolyte are prevented from deteriorating.

[0005]

However, the conventional electrolytic capacitor has the following problems.
That is, it is known that the electrolytic capacitor deteriorates with time due to use. As the deterioration with time, along with the deterioration of the dielectric oxide film on the surface of the anode foil and the deterioration of the driving electrolyte,
Hydrogen gas is generated from the capacitor element. With such deterioration over time, the characteristics (electrostatic capacity, loss, leakage current) of the electrolytic capacitor also change over time. This generally means that the capacitance decreases as the usage time increases, resulting in increased loss and leakage current.

Such deterioration with time is inevitable for electrolytic capacitors. This is not only the deterioration of the capacitor characteristics. For example, when the equipment used is at a high temperature, the electrolytic solution evaporates and thermally decomposes as one of the deteriorations of the driving electrolytic solution. When the evaporated and pyrolyzed product is cooled, it may become a liquid containing an alkali component having a high hydrogen ion concentration, depending on the constituent components of the driving electrolytic solution.
It has been confirmed that when such a liquid adheres to the lead terminal and a voltage is applied to the capacitor in this state, an erosion reaction occurs on the anode side. If the lead-out terminal corrodes in this way, if the lead-out terminal is used without being noticed, the corrosion will progress further, and eventually the lead-out terminal will be disconnected and the function of the capacitor will be lost.

In recognition of such a decrease in the reliability of the capacitor, in a device in which the capacitor is incorporated and used, the function of the device is not lost due to the decrease in the reliability of the capacitor. It corresponds to. That is, the life of an electrolytic capacitor that is actually used by incorporating it into a device is calculated by a complex calculation from Arrhenius' law (10 ° C, double rule), and estimated according to the guaranteed life of the electrolytic capacitor as a product. are doing. Then, the capacitor is replaced based on the estimated life.

Since the electrolytic capacitor is used by incorporating it into a device, the deterioration rate varies depending on the operating conditions such as operating temperature (ambient temperature). Therefore, the estimated life is
Calculated corresponding to the maximum expected ambient temperature.
Therefore, the electrolytic capacitor will actually be replaced while still fully usable. This increases the number of times the electrolytic capacitor needs to be replaced, and also increases the cost of the device incorporating the electrolytic capacitor.

By the way, with regard to deterioration over time due to the use of electrolytic capacitors, it is known that the capacitor element discolors dark brown over time due to the deterioration of the driving electrolytic solution. Therefore, the internal state of the electrolytic capacitor in use,
That is, it is possible to easily determine the deterioration state of the electrolytic capacitor by examining the degree of color change of the capacitor element. However, in the conventional electrolytic capacitor, since the capacitor element is hermetically housed in the housing case made of opaque metal, it is difficult to confirm the degree of color change of the capacitor element from the outside of the case. Therefore, it is impossible to easily determine the life of the electrolytic capacitor by examining the degree of color change of the capacitor element.

The present invention has been proposed to solve such a problem, and the first object thereof is to confirm the state of the capacitor element housed in the case from the outside of the case.
It is an object of the present invention to provide an electrolytic capacitor which can easily and accurately predict the life of the electrolytic capacitor by making it distinguishable. A second object is to provide an electrolytic capacitor that allows the inside of the case to be confirmed and discriminated from the outside and at which the case is reliably sealed. A third object is to provide an electrolytic capacitor capable of confirming / distinguishing the inside of the case from the outside without increasing the size. A fourth object is to provide an electrolytic capacitor capable of confirming / determining the state of the capacitor element inside the case and enhancing the airtightness of the case. A fifth object is to provide a method for manufacturing an electrolytic capacitor whose life can be easily grasped.

[0011]

In order to solve the above-mentioned problems, according to the present invention, a capacitor element is formed by winding an anode foil made of a valve metal and a cathode foil with a spacer interposed therebetween. In the electrolytic capacitor in which the capacitor element is impregnated with the driving electrolytic solution and hermetically accommodated in the housing case, the housing case is formed by integrally connecting a transparent resin case and a metal case. And

The invention according to claim 2 is characterized in that at least the open end of the housing case according to claim 1 is made of a metal case.

In the invention according to claim 3, the resin case according to claim 1 is formed into a cylindrical shape having a bottom surface at one end and an opening at the other end. Is formed in a cylindrical shape with both ends open, and one end of the metal case is integrally molded and connected to the opening-side end of the resin case.

In the invention according to claim 4, the metal case end connected to the resin case according to claim 1 or claim 2 or claim 3 has a stepped portion or a mesh shape having a locking portion at the edge. It is characterized in that a formed step portion is provided.

In a fifth aspect of the invention, a capacitor element is formed by winding a spacer between an anode foil and a cathode foil made of a valve metal to form a capacitor element, and the capacitor element is impregnated with a driving electrolytic solution to be housed. In a method of manufacturing an electrolytic capacitor that is hermetically housed in a case, the housing case has a bottom surface at one end, and the other end is a cylindrical transparent resin case with an opening-side end, It is characterized in that one end of a cylindrical metal case with both ends open is connected by integral molding.

[0016]

The operation of the present invention having the above construction is as follows. That is, according to the first aspect of the invention, since the transparent resin is used for the case that houses the capacitor element, the inside can be visually confirmed. This makes it possible to predict the life of the electrolytic capacitor from the change with time of discoloration due to deterioration of the capacitor element.

According to the second aspect of the invention, since the opening of the housing case is made of a metal case, the sealing plate reliably seals and prevents deterioration of the capacitor due to outside air.

According to the third aspect of the present invention, the bottom surface side of the housing case is made of a transparent resin case and the opening side is made of a metal case, and both are connected in a highly airtight state by integral molding. With this, it is possible to easily form the housing case in which the life of the electrolytic capacitor can be visually predicted.

According to the fourth aspect of the invention, the metal case and the resin case are connected in a highly airtight state, and it is possible to prevent outside air from entering the housing case.

In a fifth aspect of the present invention, by using a transparent resin in the case for accommodating the capacitor element in an easy manner, it is possible to visually confirm the inside thereof. From the change, a method of manufacturing an electrolytic capacitor is obtained that allows the life of the electrolytic capacitor to be predicted.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the electrolytic capacitor according to the present invention will be specifically described below with reference to FIGS. Here, FIG. 1 is a front sectional view showing an example of the electrolytic capacitor according to the present embodiment, and FIG. Sectional drawing, FIG. 3 is a front sectional view showing a state where the metal case of FIG. 2 is connected to a resin case by integral molding, and FIG. 4 is a front sectional view showing a structure of a housing case including a resin case and a metal case. is there.

First, as shown in FIG. 1, in the electrolytic capacitor of this embodiment, a pair of lead terminals 2 also made of aluminum are connected to a pair of anode foil and cathode foil made of high-purity aluminum foil, and The capacitor element 1 formed by winding capacitor paper between the anode foil and the cathode foil is used. The surface of the capacitor element 1 is electrochemically roughened with an etching solution or the like in order to increase the surface area of the aluminum anode foil / cathode foil. Then, a dielectric oxide film is formed on the anode foil.

Such a capacitor element 1 is impregnated with a driving electrolytic solution, which is hermetically accommodated in a cylindrical accommodating case A, one of which is a bottom surface and the other of which is an opening, to form an electrolytic capacitor. Here, in order to hermetically house the capacitor element, as means for sealing the opening of the housing case A,
The sealing plate 3 is used. The sealing plate 3 is provided with the rivet portion 4 penetrating so as to project on both sides thereof. Then, first, after connecting the lead-out terminal 2 of the capacitor element to the rivet portion 4 protruding on the back surface of the sealing plate 3, the capacitor element is housed in the housing case A. Next, the capacitor element 1
The opening of the housing case A in which is stored is bited into the sealing plate 3 by a tightening process and sealed.

In the electrolytic capacitor as described above, the housing case A is formed by integrally molding a cylindrical resin case 5 having a bottom surface made of a transparent resin having a predetermined thickness and a cylindrical metal case 6 having openings at both ends. Configured by connecting with. That is, as shown in FIG. 2, first, a step portion 8 having a slightly smaller peripheral surface is formed at one opening end of the metal case 6 which is a connection portion with the resin case 5. The edge of the stepped portion 8 is a locking portion 9 that protrudes outward and has a semicircular cross section. Then, when the resin case 5 is formed, the stepped portion 8 of the metal case 6 is embedded in the transparent resin at the end of the resin case 5 on the opening side, and is integrally molded. Next, as shown in FIG. 4, after the resin case 5 and the metal case 6 are connected by integral molding, the opening side end portion 10 of the metal case 6 is connected.
Further, the locking groove 11 for locking the sealing plate 3 is formed by drawing.

In this embodiment, the metal case 6 and the resin case 5 are constructed so that their outer circumferences have the same diameter.
Further, the step portion 8 of the metal case 6 is configured such that the inner circumference thereof is larger than the inner circumference of the resin case 5. Further, the outer periphery of the locking portion 9 is configured to have a smaller diameter than the outer periphery of the resin case 5. As a result, the metal case 6 and the resin case 5 are integrally formed and connected in a state where the step portion 8 of the metal case 6 is embedded in the resin case 5.

Regarding the electrolytic capacitor according to the present embodiment as described above, by comparing the characteristics with the conventional electrolytic capacitor,
The effects will be described. That is, a conventional electrolytic capacitor (conventional product B) in which a capacitor element is housed in a metal case, together with the electrolytic capacitor according to the present embodiment (invention product A) as described above, is rated at 85V of 600V-5500 μF.
Manufactured for ℃. In the conventional product B, the configuration of the capacitor element and the sealing plate and the connection of the rivet portion and the lead-out terminal are exactly the same, but the configuration of the housing case that houses the capacitor element is different.

For both the product A of the present invention and the product B of the related art as described above, the results at the time of performing a life test by applying a voltage of 105 ° C. and 400 V for 2000 hours (h) were examined. The results are shown in Table 1.

[0028]

[Table 1]

In this table, the confirmation result of the capacitor element after the test for 2000 hours was conducted by inspecting the inside of the housing case by opening the sealing plate of the case. As a result, in both cases, the occurrence of corrosion is similarly detected in the internal lead terminal drawn from the capacitor element.

Here, in the conventional product B, since the housing case is made of metal, it is impossible to visually confirm the inside. Therefore, you will not notice the corrosion of the lead terminals,
If the test is continued, corrosion will progress, and eventually the internal lead terminals will be disconnected and the function of the capacitor will be lost. As described above, in the conventional product B, the deterioration state of the electrolytic capacitor cannot be grasped and the electrolytic capacitor is continuously used. When the function of the capacitor is lost, the reliability of the device used is deteriorated. .

On the other hand, in the product A of the present invention, since the case that houses the capacitor element is made of transparent resin, the state inside the case can be visually discriminated. Therefore, the state of the capacitor element inside the case can be confirmed.
In this case, it has been confirmed from the outside of the case that the surface of the capacitor element has turned quite brown.
Here, it is known that in the capacitor element, the driving electrolytic solution deteriorates with time due to the use of the electrolytic capacitor, and as a result, the color changes to brown with time. Therefore, in the product A of the present invention, it can be determined that the electrolytic capacitor is considerably deteriorated from the degree of color change of the capacitor element. This agrees with the confirmation result obtained by opening the sealing plate of the housing case.

As can be seen from the above test results, according to the electrolytic capacitor of this embodiment, since the transparent resin is used in a part of the case in which the capacitor element is housed, the state inside the case can be changed from the outside. You can check. As a result, the degree of color change of the capacitor element can be confirmed from the outside of the housing case, and the degree of deterioration over time can be easily visually determined.

Moreover, since the housing case A is integrally molded so that the metal case 6 is embedded in the resin case 5 made of a transparent resin having a predetermined thickness, the resin case 5 and the metal case 6 are connected. , Its connection is sealed tightly. In particular, since the metal case 6 has the step portion 8 formed on the side of the connection portion with the resin case 5, the contact area with the resin case 5 is increased, and the airtightness is accordingly increased.

Further, at this connecting portion, an outwardly projecting locking portion 9 is formed at the end edge of the stepped portion 8 of the metal case 6, and this is embedded in the resin case 5. For this reason, even when a force is applied in the direction of separating the resin case 5 and the metal case 6, the locking portion 9 and the resin of the resin case 5 are in a state of meshing with each other, so that the resin case 5 and the metal case 6 are separated from each other. The connection does not easily come off, and the airtightness can be improved.

As described above, the housing case A including the resin case 5 and the metal case 6 of this embodiment can maintain high airtightness. Further, since the opening side of the housing case A is made of the metal case 6, it is possible to surely perform the sealing by biting the sealing plate 3.

Therefore, in this embodiment, the life of the electrolytic capacitor can be accurately and easily predicted without complicated calculation, and a new capacitor is replaced at an appropriate time before the function of the capacitor is lost. It becomes possible. As a result, the number of times the capacitor needs to be replaced can be reduced, and the cost can be reduced for the device incorporating the electrolytic capacitor. Moreover, in the electrolytic capacitor of the present embodiment, since the airtightness of the housing case A is maintained, it is possible to prevent the deterioration of the capacitor element 1 and the like inside the case due to the outside air. As a result, in a device incorporating an electrolytic capacitor, excellent capacitor characteristics and reliability can be secured without losing the function of the capacitor, and the device can be used with peace of mind.

The present invention is not limited to the above-mentioned embodiment, and the specific structure of the housing case can be changed as appropriate. For example, it is possible to configure the connecting means having high airtightness between the resin case 5 and the metal case 6 as follows. That is, as shown in FIG. 5, the stepped portion 8 of the metal case 6 is provided with the knurled portion 12 whose entire surface is in a mesh shape. As a result, when the metal case 6 is connected to the resin case 5 by integral molding, the resin enters inside the mesh of the knurled portion 12. Therefore, the contact area of the metal case inside the resin case can be increased, and the mesh of the knurled portion 12 meshes with the resin of the resin case, so that the airtightness can be improved. In this case, a locking portion can be formed on the edge of the stepped portion 8 and the airtightness can be further improved.

Further, in the present invention, the housing case A is not limited to having the same outer diameter as the metal case 6 and the resin case 5, but the outer diameter of the metal case 6 is smaller than that of the resin case 5. It can also have a large diameter. For example, the connecting means for increasing the airtightness between the metal case 6 and the resin case 5 may be configured as shown in FIG. That is, the inner diameter of the metal case 6 is formed to be the same as the inner peripheral surface of the resin case or smaller than the outer diameter of the resin case, and the outer peripheral surface of the metal case 6 serving as the connecting portion with the resin case 5 is the resin case. A step portion 13 is formed that is smaller than the outer peripheral surface of 5 and projects outward. The edge of the stepped portion 13 is a locking portion 14 that projects inward and has a semicircular cross section. The inner circumference of the locking portion 14 is configured to have a larger diameter than the inner circumference of the resin case 5. The metal case 6 configured as described above is integrally molded with the step portion 13 embedded in the resin of the resin case 5, and is connected to the resin case. In addition,
Even when the step portion is projected outward as described above, it is possible to provide the step portion 13 with the mesh-shaped knurled portion 12 as described above. Even with such a configuration, the connecting portion between the resin case 5 and the metal case 6 can ensure high airtightness as in the above-described embodiment.

Further, according to the present invention, the housing case A is not limited to the structure in which the bottom surface side of the housing case is the resin case 5, and may be composed of a plurality of metal cases and resin cases. For example, it is possible to connect the metal case, which is the bottom side of the housing case and the metal case, which is the opening side, to both opening ends of the cylindrical resin case having openings at both ends. In this case as well, the resin case and the metal case are connected to each other to be highly airtight by integral molding. Also in the electrolytic capacitor using the housing case thus configured, the inside of the housing case can be visually confirmed. Thereby, the degree of color change of the capacitor element can be determined, and the deterioration state of the electrolytic capacitor can be determined.

Furthermore, in the electrolytic capacitor and the method of manufacturing the same according to the present invention, the internal structure of the housing case can be appropriately changed. For example, the electrodes and lead terminals of the capacitor element are not limited to being made of aluminum, and other materials,
For example, the same effect can be obtained even when an electrode or terminal made of tantalum, niobium, titanium, magnesium, zirconium, or the like is used.

[0041]

As described above, according to the present invention, since the case for accommodating the capacitor element is connected by integrally molding the metal case and the transparent resin case, the degree of deterioration of the electrolytic capacitor with time is reduced. By visually observing
It is possible to provide a highly reliable electrolytic capacitor whose life can be easily predicted and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a front sectional view of an essential part showing an embodiment of an electrolytic capacitor of the present invention.

FIG. 2 is a front cross-sectional view showing a state of the metal case constituting FIG. 1 before being integrally molded with a resin case.

3 is a front cross-sectional view showing a state in which the metal case of FIG. 2 is connected to a resin case by integral molding.

FIG. 4 is a front cross-sectional view showing a housing case in which a locking groove for a sealing body is formed in the integrally molded metal case of FIG.

FIG. 5 is a front view showing, as another embodiment of the present invention, a metal case in which a connecting portion with a resin case is knurled into a mesh shape.

FIG. 6 is a front cross-sectional view showing a metal case in which a step portion protruding outward is formed at a connection portion with a resin case as another embodiment of the present invention.

FIG. 7 is a front cross-sectional view of an essential part showing a conventional electrolytic capacitor.

[Explanation of symbols]

 A: Housing case 1, 21 ... Capacitor element 2, 22 ... Lead-out terminal 3, 23 ... Sealing plate 4, 25 ... Rivet part 5 ... Transparent resin case 6, 25 ... Metal case 8, 13 ... Step part 9, 14 ... Stop portion 10 ... Opening side end portion 11 ... Locking groove 12 ... Knurled portion

Claims (5)

[Claims] 1. A capacitor element is formed by winding an anode foil made of a valve metal and a cathode foil with a spacer interposed therebetween to form a capacitor element.
In an electrolytic capacitor in which the capacitor element is impregnated with a driving electrolytic solution and hermetically accommodated in a housing case, the housing case is formed by integrally molding and connecting a transparent resin case and a metal case. Electrolytic capacitor. 2. The electrolytic capacitor according to claim 1, wherein at least the open end of the housing case is made of a metal case. 3. The resin case is formed in a cylindrical shape having a bottom surface at one end and the other end opened, and the metal case is formed in a cylindrical shape opened at both ends. 2. The electrolytic capacitor according to claim 1, wherein the housing case has one end of the metal case integrally connected to an end of the resin case on the opening side. 4. An end portion of the metal case connected to the resin case is provided with a step portion having a locking portion at an edge or a step portion formed in a mesh shape. The electrolytic capacitor according to claim 1, claim 2, or claim 3. 5. A capacitor element is formed by winding an anode foil and a cathode foil made of a valve metal with a spacer interposed therebetween to form a capacitor element.
In a method of manufacturing an electrolytic capacitor in which this capacitor element is impregnated with a driving electrolytic solution and hermetically accommodated in a housing case, the housing case has a bottom surface at one end and an opening at the other end. A method for manufacturing an electrolytic capacitor, characterized in that one end of a cylindrical metal case having both ends open is connected to the opening-side end of a transparent resin case by integral molding.