JP2019096847A - Capacitor - Google Patents

Abstract

To provide a capacitor capable of restraining occurrence of poor soldering at the time of reflow mounting due to internal-pressure rise.SOLUTION: A capacitor includes a capacitor element where lead-out lead wires are connected with an anode foil and a cathode foil, respectively, and the anode foil and cathode foil are wound via a separator, a bottomed cylindrical outer case for receiving the capacitor element impregnated with polymer electrolyte, a sealing body for sealing the opening end of the outer case and having an insertion hole into which the lead-out lead wires connected with the capacitor element are inserted, and a seat plate attached to the opening end side of the outer case, and supporting the lead-out lead wires. In the inner peripheral surface of the cylindrical part of the outer case, a recess is formed in the hoop direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a capacitor, and more particularly to a surface-mounted capacitor mounted on the surface of a substrate by a reflow process.

  As shown in FIG. 7, there is a conventional electrolytic capacitor 1 mounted on a substrate by a reflow process. In the manufacturing process of this electrolytic capacitor, high purity aluminum foil is subjected to etching treatment to enlarge the surface area. Then, the aluminum foil is subjected to a chemical conversion treatment to manufacture an anode foil and a cathode foil on which an oxide film to be a dielectric of a capacitor is formed. The anode foil and the cathode foil (hereinafter collectively referred to as electrode foils) are wound via a separator, and the lead wires 4 for taking out the electrodes from the electrode foils are crimped by needle holes or ultrasonic waves. The capacitor element 2 is manufactured by bonding using a method such as welding.

  Subsequently, the capacitor element 2 is impregnated with an electrolyte, and the impregnated capacitor element 2 is housed in the bottomed cylindrical outer case 3. An aluminum case is mainly used for the exterior case 3.

  The open end of the outer case 3 is sealed by a sealing body 5 having an insertion hole through which the lead wire 4 is inserted. As the sealing member 5, an elastic rubber such as isobutylene-isoprene rubber (IIR) or ethylene propylene terpolymer (EPT) is mainly used.

  The gap between the lead wire insertion hole of the sealing body 5 is sealed by inserting the lead wire 4.

  A seat plate 6 made of resin or the like, having an insertion hole through which the lead wire 4 can be inserted, is attached to the sealing body of the capacitor body, and a terminal groove provided in the seat plate is attached to the capacitor body thus manufactured. The lead wire 4 is bent along it to form a shape compatible with surface mounting.

  As described above, the electrolytic capacitor 1 uses, as the electrolyte, an electrolytic solution containing γ-butyrolactone or ethylene glycol as a main solvent, or a solid electrolyte such as polythiophene or polypyrrole.

  In the electrolytic capacitor 1, when temperature, voltage, ripple current, etc. exceeding specifications / standards are applied, gas or liquid vaporization occurs due to the reaction of the electrolyte, and the internal pressure of the exterior case 3 gradually increases. There is a risk of explosion. Therefore, as shown in Patent Document 1, by providing a pressure valve on the bottom surface of the outer case of the electrolytic capacitor, when the internal pressure of the outer case reaches the valve operating pressure, the internal pressure is increased by operating the pressure valve. It escapes and prevents the electrolytic capacitor from bursting.

Unexamined-Japanese-Patent No. 2003-309047

  By the way, the electrolytic capacitor 1 is surface-mounted by a reflow process at the time of substrate mounting. In this reflow process, a cream solder is applied to the substrate land pattern using a screen mask, and in a state in which other surface mount components including the electrolytic capacitor 1 are mounted, the substrate itself is in a high temperature atmosphere above the solder melting temperature. Solder inside.

  In this reflow process, although the pressure condition is set so as not to operate, when the electrolytic capacitor 1 itself mounted on the substrate is placed in a high temperature atmosphere, the electrolytic solution contained inside or the unpolymerized solid electrolyte or The evaporation of the solvent takes place and the internal pressure of the condenser body rises. As shown in FIG. 8 (b), only the outer case 3 and the seat plate 6 of the electrolytic capacitor 1 are schematically shown by the increase of the internal pressure P (the pressure represented by the arrow P in FIG. 8 (b)). The deformation of the sealing body may be caused, and the deformation due to the pressure of the seat plate 6 may occur. As a result, as shown in FIG. 7 (b), there is a problem that the lead wire lead 4 is lifted from the bottom surface of the seat plate 6 and causes a soldering defect with the substrate on which the electrolytic capacitor 1 is mounted. there were.

  The present invention has been made in consideration of the above points, and it is an object of the present invention to provide a capacitor capable of suppressing the occurrence of a soldering defect due to an increase in pressure inside an outer case at the time of reflow mounting.

  The capacitor according to the present invention includes a capacitor element in which a lead wire is connected to each of an anode foil and a cathode foil, and the anode foil and the cathode foil are wound via a separator, and the capacitor element impregnated with an electrolyte. A bottomed cylindrical exterior case to be stored, a sealing body having an insertion hole for sealing the open end of the exterior case and inserting the lead wire connected to the capacitor element, and the opening of the exterior case A seat plate attached to the end side and supporting the lead-out lead wire is provided, and a concave portion is formed along the circumferential direction on the inner peripheral surface of the cylindrical portion of the outer case.

  According to this configuration, deformation of the seat plate is suppressed by making it easy to deform the peripheral side surface portion of the outer case in response to an increase in internal pressure, and a soldering defect between the mounting target and the substrate to be mounted is prevented. Can be prevented.

  Further, in the capacitor of the present invention according to the above-mentioned configuration, the recess is continuously formed in the circumferential direction of the inner peripheral surface on the inner peripheral surface of the cylindrical portion of the outer case.

  According to this configuration, the concave portion is continuously formed, thereby avoiding concentration of the internal pressure of the outer case at one position as compared with the case where the concave portion is locally formed at one position. As a result, it is possible to absorb an increase in internal pressure due to the deformation of the peripheral side surface portion of the cylindrical portion while avoiding the formation of a hole in the concave portion.

  ADVANTAGE OF THE INVENTION According to the capacitor | condenser of this invention, the electrolytic capacitor which can suppress generation | occurrence | production of the soldering defect by the raise of the exterior case internal pressure at the time of reflow mounting can be provided.

It is a sectional view showing the composition of the electrolytic capacitor concerning the embodiment of the present invention. It is a perspective view showing a capacitor element concerning an embodiment of the present invention. It is an approximate line perspective view showing composition of a crevice concerning an embodiment of the present invention. It is a fragmentary sectional view showing composition of a crevice concerning an embodiment of the present invention. It is a schematic diagram by which it uses for explanation of operation of an embodiment of the present invention. FIG. 10 is a perspective view showing the configuration of a recess according to another embodiment. It is sectional drawing which shows the conventional electrolytic capacitor. It is a schematic diagram by which it uses for description of the problem of the conventional electrolytic capacitor.

Hereinafter, embodiments of the present invention will be described in detail based on the attached drawings.
FIG. 1, in which parts corresponding to those in FIG. 7 are assigned the same reference numerals, shows a partial cross-sectional view of the electrolytic capacitor 10 of the present embodiment, and FIG. 2 is a perspective view showing the capacitor element 2 of the electrolytic capacitor 10. is there.

  As shown in FIG. 1 and FIG. 2, the electrolytic capacitor 10 in this embodiment connects the lead-out lead wire 4 for electrode extraction to the anode foil 7a and the cathode foil 7b which formed the chemical conversion film in aluminum foil, 7c, a closed-end cylindrical metal outer case 13 for containing the capacitor element 2 wound through 7c and the electrolytic solution impregnated capacitor element 2, and the open end of the outer case 13 sealed A capacitor body formed of an elastic sealing body 5 having an insertion hole through which the lead wire 4 connected to 2 is inserted, and a resin, and an insertion hole and a lead wire through which the lead wire 4 is inserted A seat plate 6 having a terminal groove for receiving 4 is attached.

The seat plate 6 is fixed by bending the lead wire 4 inserted through the insertion hole of the seat plate 6 and storing it in the terminal groove of the seat plate 6.
A part of the lead wire 4 supported by the seat plate 6 is supported in a state of being exposed from the lower surface of the seat plate 6, and this part is soldered to a substrate which is a real object at the time of reflow mounting.

  The exterior case 13 is a case manufactured using aluminum as a raw material. On the other hand, the sealing body 5 is made of an elastic rubber such as isobutylene-isoprene rubber (IIR) or ethylene propylene terpolymer (EPT).

  A recess 8 acting as a pressure valve is formed on the inner surface of the bottom portion 13a of the outer case 13 having a bottomed cylindrical shape, and the recess 8 operates with an increase in the internal pressure, whereby the internal pressure is externally output. It is configured to escape.

  In addition, as shown in FIGS. 1 and 3, the inner peripheral surface of the cylindrical portion (peripheral side surface portion 13b) of the outer case 13 has a circumferential direction (direction of arrow a) over the entire inner peripheral surface (one turn). The recessed part 18 which follows (1) is formed by cutting or pressing. As shown in FIG. 4A, this recess 18 is formed so that the cross-sectional shape of a predetermined depth D and width W is a quadrangle, and is continuously formed so as to go around the inner peripheral surface of the outer case 13 It is done.

  The central portion of the peripheral side surface portion 13b of the outer case 13 in the height direction (the winding axis direction of the capacitor element 2, the direction of the arrow b) is formed with the concave portion 18 so that the thin portion easily deformed by the concave portion 18 Will have. Thereby, when the internal pressure of the exterior case 13 rises, the circumferential side surface portion 13b is easily deformed outward. The relationship between the internal pressure and the deformation of the peripheral side surface portion 13b is determined by the depth D and the width W of the recess 18 with respect to the size (including the thickness of the peripheral side surface portion 13b) and shape of the outer case 13 The size is determined by the size and shape of the electrolytic capacitor 10 and the reflow conditions such as the temperature at the time of mounting the electrolytic capacitor 10 on a substrate.

Next, a method of manufacturing the present electrolytic capacitor will be described.
First, an etching process is performed on a high purity aluminum foil to enlarge a surface area, and an anode foil on which an oxide film to be a dielectric of a capacitor is formed by performing a conversion process on the aluminum foil, and an etching processed cathode foil Make The lead wire 4 is joined to the anode foil and the cathode foil (hereinafter both are collectively referred to as “electrode foil”) by needle hole caulking, ultrasonic welding or the like, and wound through a separator. , And capacitor element 1 are manufactured.

  Subsequently, the capacitor element 2 is impregnated with an electrolytic solution, and the impregnated capacitor element 2 is accommodated in the outer case 13. Thereafter, the opening end of the exterior case 13 in which the capacitor element is stored is sealed by the sealing body 5.

  In addition, the clearance gap is sealed by making the extraction | lead-out lead wire penetration hole of the sealing body 5 penetrate the extraction lead wire 4 joined to electrode foil. At this stage, the capacitor body is completed.

  Then, after inserting the lead wire 4 drawn from the capacitor body into the insertion hole of the seat plate 6, the seat plate 6 is inserted into the capacitor body by bending the lead wire 4 along the terminal groove communicating with the insertion hole. Fix it and make it a shape that can be used for surface mounting.

  The electrolytic capacitor 10 manufactured as described above is surface-mounted by a reflow process at the time of substrate mounting. In this reflow mounting, in a state where cream solder is applied to a substrate land pattern using a screen mask and a component is mounted, the substrate itself is soldered in a high temperature atmosphere higher than the solder melting temperature.

  In the reflow process, the electrolytic capacitor itself mounted on the substrate is placed in a high temperature atmosphere, so that the electrolytic solution contained inside is vaporized, and the internal pressure of the capacitor body rises. The rise of the internal pressure may cause deformation of the outer case 13.

  As the external case 13 and the seat plate 6 are schematically shown in FIG. 5, when the internal pressure of the electrolytic capacitor 10 (FIG. 5 (a)) rises (FIG. 5 (b)), the external case 13 and the sealing member 5 An internal pressure indicated by an arrow P in FIG. 5B is applied to (FIG. 1). The outer case 13 is formed in a cylindrical shape with a bottom, the open end is sealed by the sealing body 5 (FIG. 1), and the internal pressure P is absorbed by the deformation of the outer case 13.

  Here, the exterior case 13 is sealed by the cylindrical peripheral side surface portion 13b, the flat bottom portion 13a, and the sealing member 5 provided at the opening end, so that the internal pressure P has a curved surface configuration. The peripheral side surface portion 13b is basically shaped so as to have high strength and is less likely to be deformed than the bottom portion 13a of the plane configuration, but in the case of this embodiment, the recess 18 is circumferentially formed on the inner peripheral surface of the peripheral side surface portion 13b By being formed along, the circumferential side surface portion 13b is easily deformed as compared with the case where the recess 18 is not formed, since the thickness of the portion where the recess 18 is formed is smaller. It has become.

  As a result, as shown in FIG. 5 (b), deformation due to the internal pressure P is generated in the peripheral side surface portion 13 b of the outer case 13, and deformation of the sealing body 5 (seat plate 6) is suppressed. It is possible to suppress the occurrence of soldering defects with the substrate to be mounted.

Incidentally, the concave portion 18 is continuously formed so as to make a round on the inner peripheral side surface of the outer case 13, so that the internal pressure is generated in the concave portion 18 compared with, for example, one local location. A concentrated action can be avoided, and an increase in internal pressure can be absorbed by the deformation of the peripheral side surface portion 13b while avoiding the formation of a hole in the peripheral side surface portion 13b.
Further, by forming the concave portion 18 on the inner peripheral surface side of the peripheral side surface portion 13 b, it is possible to suppress the formation of a hole in the peripheral side surface portion 13 b as compared to the case where it is formed on the outer peripheral surface side. .

  The outer case 13 according to the present embodiment has a height of 10.6 mm, a diameter of 10.0 mm, a wall thickness of 0.28 mm, and a recess formed in the peripheral side surface portion 13b has a width W of 0.30 mm and a depth D It is 0.2 mm (FIG. 4A), and the size and shape of the recess 18 are determined in accordance with these dimensions and the reflow conditions at the time of mounting. There are various sizes and shapes of the electrolytic capacitor 10, and accordingly, the recess 18 can have various dimensions.

  In the above embodiment, as shown in FIG. 4A, the case where the recess 18 is formed to have a quadrangular cross-sectional shape has been described. However, the present invention is not limited to this. Recesses of various shapes can be applied, such as forming a semicircular cross-sectional shape as shown in b) or a triangular cross-sectional shape as shown in FIG. 4 (c).

  Moreover, in the above-mentioned embodiment, although the case where the recessed part 18 continuous over the perimeter was formed in the inner skin of peripheral side part 13b of exterior case 13 was described, it is not restricted to this, for example As shown in 6, as the configuration of the recess 18, it may be configured to be intermittently connected to the inner peripheral surface of the peripheral side surface portion 13 b. In this configuration, it is preferable that the total of forming the recesses 18 with respect to the circumferential length be at least half or more.

  In the above embodiment, although the present invention is applied to the electrolytic capacitor 10, the present invention is not limited to this, and the present invention is not limited to this. It can be widely applied.

DESCRIPTION OF SYMBOLS 1 and 10 Electrolytic capacitor 2 Capacitor element 3 and 13 Outer case 13a Bottom part 13b Peripheral side part 4 Lead wire 5 Sealing body 6 Seat plate 7a Anode foil 7b Cathode foil 7c Separator 8 and 18 Concave part

Claims (2)

A capacitor element in which a lead wire is connected to each of the anode foil and the cathode foil, and the anode foil and the cathode foil are wound via a separator;
A bottomed cylindrical outer case for housing the capacitor element impregnated with electrolyte;
A sealing body having an insertion hole for sealing the open end of the outer case and inserting the lead wire lead connected to the capacitor element;
A seat plate attached to the open end of the outer case and supporting the lead wire;
A recess is formed along the circumferential direction on the inner peripheral surface of the cylindrical portion of the outer case. The said recessed part is continuously formed in the circumferential direction of the said internal peripheral surface in the internal peripheral surface of the cylindrical shape part of the said exterior case. The capacitor | condenser of Claim 1 characterized by the above-mentioned.

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