JPH0119247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chip type electrolytic capacitor.

In recent years, with advances in semiconductor technology such as ICs and LSIs, electronic devices have become increasingly smaller and more sophisticated, and automatic insertion and mounting of components are also being implemented in terms of assembly and mounting technology. In capacitors, chip components without lead wires are now in practical use, such as multilayer ceramic capacitors and tantalum capacitors. However, since electrolytic capacitors use an electrolytic solution, there are problems such as the structure of the sealing part becoming complicated and expensive when trying to make it into a chip.
Therefore, relatively small electrolytic capacitors with lead wires were used, and they were shared with other chip components, making the mounting method complicated. Therefore, as shown in FIG. 1, an insulating container 2 made of synthetic resin or the like that houses a capacitor element 1 is capped with a crown-shaped metal cap 4 having a solderable metal surface 3 on the outside at both ends. However, since the electrolyte leaks from the fitting part between the insulating container 2 and the crown-shaped metal cap 4, it is necessary to apply the adhesive with an elastic body interposed, and the fitting part is connected to the two ends of the cap. In some places, it lacked airtightness.

The present invention eliminates the above-mentioned drawbacks and provides a small and highly reliable chip electrolytic capacitor.

The present invention will be described below with reference to embodiments shown in FIGS. 2 to 12.

Figure 2 is a cross-sectional view of the case of a chip-type electrolytic capacitor, in which a solderable metal layer 6 of nickel, copper, etc. is electrolessly plated or vapor-deposited on the bottomed peripheral edge of a bottomed cylindrical metal case 5 made of aluminum or the like. A solder layer 7 is formed thereon by solder plating. FIG. 3 shows a metal terminal 8 for an anode, which is formed by press-molding a chemically convertible metal such as aluminum to form a T-shaped cross section consisting of a small diameter part 8a and a large diameter part 8b, and the periphery of the large diameter part 8b. A solderable metal layer 6 of nickel, copper, etc. is formed on the surface by electroless plating, vapor deposition, etc., and a solder layer 7 is formed thereon by solder plating. Further, the outer diameter of the large diameter portion 8b is approximately equal to or slightly larger than the outer diameter of the metal case 5. FIG. 4 shows an annular elastic body 9 made of silicone rubber, etc., with a hole 9a provided in the center for mounting the small diameter part 8a of the metal terminal 8, and the outer diameter of the elastic body 9 is set in the hole 9a. The metal case 5 is configured such that it can be attached to the metal case 5 and inserted into the opening of the metal case 5. Figure 5 is a cross-sectional view of a chip-type electrolytic capacitor, which is made of aluminum, etc., in the form of a plate with a thickness of 0.1 to 0.2 mm or a wire with a diameter of about 0.6 mm, by welding and caulking the electrode foil for the anode and the electrode foil for the cathode. The anode tab 10 and the cathode tab 11 are connected to each other and wound through a separator such as electrolytic paper to form a capacitor element 12. Next, an elastic body 9 is attached to the periphery of the small diameter portion 8a of the metal terminal 8, and the anode metal terminal 8, anode tab 10,
After welding the metal case 5 and the cathode tab 11, the capacitor element 12 is impregnated with an electrolytic solution,
This is stored in a metal case 5, and the small diameter part 8a of the metal terminal 8 is attached to the opening of the metal case 5, and the opening of the metal case 5 is sealed by winding.
It is completed by covering with insulating material 13. The insulating material 13 may be coated with a relatively heat-resistant heat-shrinkable tube such as polyester, or may be coated with epoxy resin. Further, the electrolytic solution may be impregnated with the above-described anode tab 10 and cathode tab 11 before welding.

The chip type electrolytic capacitor of the present invention is manufactured as described above.

Therefore, the T-shaped large diameter portion 8b of the metal terminal 8 has a solderable metal surface that can be directly connected to a printed circuit board, and the small diameter portion 8a is connected to the opening of the bottomed metal case 5 via the elastic body 9. Since the parts are sealed and sealed, the airtightness is significantly improved, and the electrolyte will not leak out due to heating when mounted on a printed circuit board and soldered.
Extremely stable characteristics can be maintained without any increase in tan δ. In addition, since the anode side of the metal terminal 8 and the cathode side at the bottom of the metal case 5 are configured to be symmetrical in terms of weight, they can be easily aligned in the same direction when automatically supplying capacitors, so polarity can be determined. There is no need to provide a mechanism, and productivity can be significantly improved.

Figures 6 to 11 show other embodiments of the components of chip-type electrolytic capacitors, and Figure 6 shows the bottom and part of the periphery of a metal case made of aluminum or other metals made of solderable metals such as nickel or copper. The metal layer 6 may be formed on the entire peripheral portion. FIG. 7 shows a cap 14 whose outer surface is plated with solder, tin, etc. and is connected to the bottom of the metal case 5 by fitting and welding, and FIGS. 8 and 9 show a metal terminal 8 in the same manner. A metal layer 6 or a metal cap 14 is integrally formed on the outer surface of the cap, and can be manufactured in the same manner as in the embodiments described above. Moreover, FIGS. 10 and 11 show a structure in which a convex portion 8c having an outer diameter larger than the small diameter portion 8a and smaller than the large diameter portion 8b is integrally formed on the inside of the metal terminal 8, and the cross section is formed into a square shape. When the small diameter portion 8a of the metal terminal 8 is attached to the opening of the metal case 5 through the wire 9 and tightened, the airtightness is further improved and the operating temperature range can be expanded. In this case, an explosion-proof mechanism may be added by providing a plurality of linear grooves along the outer peripheral surface or inner peripheral surface of the metal case 5 in the axial direction. Further, the shape of the metal case 5 is not limited to a cylindrical shape, but can be set to an elliptical shape, a polygonal shape, etc. as necessary.

In addition, in the above-mentioned embodiment, the embodiment in which the elastic body 9 and the anode metal terminal 8 are integrally formed is also included.

The table below shows the results of a 96-hour pressure vacuum test on a chip-type electrolytic capacitor with a rating of 16 V and 10 μF at 120°C and 2 atmospheres. It was demonstrated that the increase in tan δ was small and extremely stable, there was no electrolyte leakage, and the airtightness was high.

As mentioned above, the chip-type electrolytic capacitor of the present invention is small and can be produced at low cost, and has extremely advantageous effects in terms of quality and assembly and mounting, and has great industrial and practical value. It is.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional chip type electrolytic capacitor, and Figures 2 to 12 are examples of the present invention.
Figures 6 and 7 are cross-sectional views of the metal case;
Figure 3 shows the metal terminal for the anode, A is a bottom view, B is a cross-sectional view, Figure 4 is a perspective view of the elastic body, Figures 5 and 12 are cross-sectional views of the chip type electrolytic capacitor, and Figure 8 is a cross-sectional view of the chip type electrolytic capacitor.
9 and 9 are cross-sectional views of other metal terminals for anodes,
Figures 10 and 11 are cross-sectional views of other anode metal terminals and elastic bodies attached, and Figure 13 is a tan δ characteristic diagram before and after the pressure-jerker test comparing the conventional product and the product of the present invention. . 5: Metal case, 8: Metal terminal for anode, 8a:
Small diameter part, 8b: Large diameter part, 9: Elastic body, 10: Anode tab, 11: Cathode tab, 12: Capacitor element.

Claims (1)

[Claims] 1 A metal case made of aluminum or the like in a bottomed cylindrical shape having solderable metal at least on the bottomed peripheral edge, and a T-shaped or square-shaped cross section consisting of a small diameter part and a large diameter part, A metal terminal for an anode made of aluminum or the like having a solderable metal on at least the peripheral edge of the diameter part, and an elastic body attached to the peripheral edge of the small diameter part of the metal terminal,
The anode tab led out from the capacitor element is connected to the metal terminal, the cathode tab led out from the capacitor element is connected to the metal case, the capacitor element is housed in the metal case, and the capacitor element is inserted into the opening of the metal case. Attach the small diameter part of the metal terminal,
A chip-type electrolytic capacitor characterized by a metal case whose opening is sealed by seaming.