JPH0614504B2 - Aluminum electrolytic capacitor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum electrolytic capacitor, and more specifically to a so-called vertical surface-mounted aluminum electrolytic capacitor.

Structure of conventional example and its problems Conventional surface mounting aluminum electrolytic capacitors of this type are
It is configured as shown in FIGS. That is, an anode foil having a roughened aluminum foil and further formed with a dielectric oxide film by anodic oxidation, and a cathode foil formed by roughening the aluminum foil are wound around a separator and impregnated with a driving electrolytic solution. To form an aluminum electrolytic capacitor element 1, and the aluminum electrolytic capacitor element 1 is housed in a cylindrical metal case 2 having a bottom, and the open end is sealed with a sealing material 3 having elasticity such as rubber so that the aluminum electrolytic capacitor element 1 is sealed. A capacitor body is configured, and the lead wire 4 drawn out from the aluminum electrolytic capacitor body is electrically and mechanically connected to the comb-shaped terminal 5 by a method such as welding, and the whole excluding the comb-shaped terminal 5 is molded. A resin exterior 6 was applied to complete the aluminum electrolytic capacitor.

Such an aluminum electrolytic capacitor is provided with the mold resin sheath 6 as described above in order to have solder heat resistance when mounted on a printed circuit board. Generally, the mold resin sheath has a temperature of 100 ° C. to 150 ° C. in, and pressurized at a pressure of about 5 minutes 10 kg / cm ^2, in such severe conditions, and transpiration driving electrolyte for aluminum electrolytic capacitor body, such as an increase of loss and tanδ of the capacitance However, there is a problem in that it becomes extremely expensive because of the deterioration of the characteristics described above and because of the molding resin exterior 6. Furthermore, since it is a horizontal type, when it is mounted on a printed circuit board, it occupies a large area of the printed circuit board, which is a factor that hinders miniaturization of various devices.

OBJECT OF THE INVENTION The present invention eliminates such conventional drawbacks, and an object of the present invention is to provide an inexpensive vertical type surface mount aluminum electrolytic capacitor which is free from characteristic deterioration.

According to the present invention, in order to achieve the above object, an aluminum electrolytic capacitor element is housed in a case, and the aluminum electrolytic capacitor element has a thickness of 0.5 mm or more and a value of 0.
An elastic body made of any one of styrene butadiene rubber having a thickness of 7 mm or less, ethylene propylene terpolymer, isobutyl isopropylene rubber, isobutyl rubber, and fluororubber, and a polyimide having a thickness of 1.0 mm or more and 1.5 mm or less. An aluminum electrolytic capacitor body which is constructed by sealing using a non-elastic two-layer structure sealing member made of any one of polyamide-imide, and which has lead wires connected to the aluminum electrolytic capacitor element drawn out from the same end face. , An insulating plate having a through hole through which the lead wire penetrates, which is arranged so as to abut the end surface of the lead wire of the aluminum electrolytic capacitor body, and penetrates the through hole of the insulating plate. The tip of the lead wire is bent along the outer surface of the insulating plate.

With such a configuration, the mounting work when mounting the aluminum electrolytic capacitor on the surface of the printed circuit board can be performed extremely well, and the speed can be increased.

Moreover, since polyimide and polyamide-imide have excellent heat resistance, it is possible to provide a surface mount aluminum electrolytic capacitor having improved solder heat resistance.

Description of Embodiments An aluminum electrolytic capacitor according to an embodiment of the present invention will be described below with reference to the drawings of FIGS. 2 to 4. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals.

In the figure, reference numeral 1 is an aluminum electrolytic capacitor element similar to the conventional one, in which a high-purity aluminum foil is electrochemically roughened and then anodized to form a dielectric oxide film. It is constituted by winding the formed cathode aluminum foil with an insulating paper in between, and impregnating the wound product with a driving electrolytic solution. The aluminum electrolytic capacitor element 1 is housed in a cylindrical metal case 2 having a bottom. Also, the aluminum electrolytic capacitor element 1
The lead wire 4 is connected to the anode foil and the cathode foil.

The open end of the metal case 2 has an elastic body 7a made of styrene-butadiene rubber having a thickness of 0.6 mm and a non-elastic body 7 made of polyimide having a thickness of 1.1 mm.
The sealing member 7 having a double-layered structure with b is mounted and drawn by performing a drawing process, thereby forming the aluminum electrolytic capacitor body. The lead wire 4 connected to the aluminum electrolytic capacitor element 1 penetrates the sealing member 7 and is drawn out from the same end face to the outside.

Reference numeral 8 denotes an insulating plate arranged so as to come into contact with the end surface of the lead wire 4 of the aluminum electrolytic capacitor main body, and the insulating plate 8 is provided with a through hole 8a through which the lead wire 4 penetrates.

Further, a concave portion 8b connected to the through hole 8a is provided on the outer surface of the insulating plate 8, and the tip end portion 4a of the lead wire 4 penetrating the through hole 8a is bent so as to fit in the concave portion 8b. ing. In this case, as shown in FIGS. 4A and 4B, the lead wire 4 of the round bar may be a bent tip wire having a flattened end 4a, or may be the lead wire of the round bar as it is. good.

A solder heat resistance test of the surface-mount type aluminum electrolytic capacitor having the above configuration was conducted. The sample was placed on a hot plate at 250 ° C. for 1 minute, and then the characteristics of capacitance, tan δ, and leakage current were measured, but normal values were shown.

In the above embodiment, the elastic member 7a made of styrene-butadiene rubber that constitutes the sealing member 7 has a thickness of 0.6 mm, but the thickness is not limited to 0.6 mm. When it is used in a device to which little vibration is applied, 0.2 mm or more is sufficient. That is, the function of the elastic body 7a is to prevent liquid leakage in the aluminum electrolytic capacitor in a heat cycle test in which the aluminum electrolytic capacitor using the sealing member 7 is repeated 200 times at -40 ° C and + 150 ° C for 30 minutes each. However, as a result of confirming experimentally, the minimum thickness at which the leakage preventing effect is obtained is 0.
It is 2 mm, and when it is 0.2 mm or less, the liquid leakage occurrence rate rapidly increases from 1% or less to nearly 30%. Also, when using an aluminum electrolytic capacitor in a state where a vehicle is constantly vibrated, it is necessary to prevent leakage by applying a vibration stress to the aluminum electrolytic capacitor for twice the time determined by Japanese Industrial Standards in a vibration test. The thickness where the effect is greatly recognized is 0.7 mm, and even if the thickness is 0.7 mm or more, the leakage prevention effect does not change, and conversely, the size in the height direction of the aluminum electrolytic capacitor is increased more than necessary. . Also,
Under this condition, the leakage rate of 75% is 75% when the thickness of the elastic body 7a is 0.3 mm, 25% when the thickness is 0.5 mm, and 1% when the thickness is 0.7 mm or more. It can be said that the thickness of the elastic body 7a satisfying both the conditions of vibration stress and vibration stress is 0.5 mm or more and 0.7 mm or less.

Further, in the above-mentioned embodiment, the case where the thickness of the non-elastic body 7b constituting the sealing member 7 is 1.1 mm has been described, but this thickness is not limited to 1.1 mm,
It should be 1.0 mm or more. That is, the function and role of the non-elastic body 7b is to maintain the rigidity and strength of the sealing member 7, but as a result of measuring the thermal expansion deformation dimension with the reflow soldering temperature of 230 ° C., the non-elasticity of the sealing member 7 is measured. When the thickness of the body 7b is 0.5 mm, it is 0.08 mm, and when the thickness is 0.5 mm or less, it is 0.10 mm or more and the rigidity cannot be maintained, and when the thickness is 0.5 mm or more, the thermal expansion deformation dimension is 0. There was almost no change from 08 mm to 0.07 mm.

On the other hand, in the overvoltage test and the experiment of abnormal heat stress of 250 ° C in the reflow soldering process, the thickness of the non-elastic body 7b that withstands the internal pressure of the aluminum electrolytic capacitor is 1.0 mm
In the following, the thermal expansion deformation dimension is 0.10 mm or more and the rigidity cannot be maintained. When the thickness is 1.0 mm, the thermal expansion deformation dimension is 0.10 mm, and when the thickness is 1.5 mm, the thermal expansion deformation dimension is 0.08 mm. When the thickness was 1.5 mm or more, the thermal expansion deformation dimension was 0.08 mm, which was almost unchanged. Therefore, the thickness of the non-elastic body 7b satisfying both the reflow soldering temperature of 230 ° C. and the abnormal heat stress of 250 ° C. is 1.0 mm or more and 1.5 mm.
The following are appropriate and practically effective.

Further, in the above-mentioned embodiment, the one in which styrene-butadiene rubber is used as the elastic body 7a of the sealing member 7 has been described, but ethylene propylene terpolymer, isobutyl isopropylene rubber, isobutyl rubber, fluororubber may be used instead. .

Further, as the non-elastic body 7b, polyamideimide may be used instead of polyimide.

With such a structure, when mounting on a printed circuit board, as shown in FIG. 5, the surface mount type aluminum electrolytic capacitor 21 of the present invention is mounted on the printed circuit board 22 so that the terminal portion by the lead wire is conductive. The terminal part of the aluminum electrolytic capacitor 21 is connected and fixed to the conductive pattern 23 of the printed circuit board 22 by the solder 25 by arranging so as to contact the pattern 23, temporarily fixing it with the adhesive 24, and then using a soldering method such as reflow. do it. Further, if cream solder is used as the solder, it can be temporarily fixed without using an adhesive, and in this case, mounting becomes easy.

As described above, according to the aluminum electrolytic capacitor of the present invention,
Since the insulating plate is used, there is no inclination or wobbling during surface mounting on the printed circuit board, which allows the mounting work to be performed extremely favorably and also speeds up. Also, because the mold resin exterior is not done,
An aluminum electrolytic capacitor without characteristic deterioration can be manufactured at low cost, and since a sealing member made of polyimide or polyamide-imide is used, the heat resistance can be improved.

[Brief description of drawings]

1a and 1b are a sectional view and a side view showing a conventional aluminum electrolytic capacitor, FIG. 2 is a perspective view showing an aluminum electrolytic capacitor according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. 4A and 4B are perspective views showing a lead shape according to an embodiment of the present invention, and FIG. 5 is a front view showing a surface mounting state of the aluminum electrolytic capacitor on a printed circuit board. 1 ... Capacitor element, 2 ... Metal case, 4 ... Lead wire, 7 ... Sealing member, 7a ... Elastic body, 7b ... Inelastic body, 8 ... Insulating plate, 8a ... Through hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kinfumi Saeki Kinbumi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Within

Claims (2)

[Claims] 1. A styrene butadiene rubber, ethylene propylene terpolymer, isobutyl isopropylene rubber, isobutyl rubber, fluororubber having a thickness of 0.5 mm or more and 0.7 mm or less in which an aluminum electrolytic capacitor element is housed in a case. An elastic body made of any of the following:
It is constituted by sealing using a non-elastomeric two-layer structure sealing member made of either polyimide or polyamide-imide having a thickness of 0 mm or more and 1.5 mm or less, and is connected to the aluminum electrolytic capacitor element. An aluminum electrolytic capacitor body having lead wires drawn from the same end surface, and an insulating plate provided so as to come into contact with the lead wire drawn end surface of the aluminum electrolytic capacitor body and having a through hole through which the lead wire passes. And an end portion of a lead wire penetrating a through hole of the insulating plate, which is bent along an outer surface of the insulating plate. 2. The aluminum electrolytic capacitor according to claim 1, wherein the bent lead wire has a plate-shaped tip portion.