JPS6116680Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid electrolytic capacitor in which a cathode lead member is directly bonded to a graphite layer without providing a metal layer or a solder layer.

A conventional general solid electrolytic capacitor consists of a metal substrate, an anodized film, a semiconductor metal oxide layer, a graphite layer, a metal layer made of silver paint, a solder layer for bonding the cathode lead member, and an exterior insulating layer. It is made up of things. However, there was a risk that cracks would occur in the oxide film due to thermal stress during soldering to connect the cathode lead members, causing leakage current. Furthermore, there was also a risk that the solder bonding the cathode lead members would melt and blow out during heating for soldering to a printed circuit board. Furthermore, expensive silver paint must be used, which necessarily increases the cost of the device.

In order to solve the above-mentioned drawbacks, solid electrolytic capacitors have been proposed in which cathode lead members are connected without using silver paint or solder. FIG. 1 is an explanatory diagram of this type of solid electrolytic capacitor, which consists of a metal substrate 1 made of a metal plate or powder sintered body of tantalum, aluminum, titanium, niobium, etc., on which an anodized film can be formed. , an anode lead member 2 fixed to the metal substrate 1 by welding or embedding, an anodic oxide film 3 formed on the outer circumferential surface of the metal substrate 1 by electrolytically etching the surface to provide unevenness, and the anodic oxide film 3. Film 3
A semiconductor metal oxide layer 4 made of, for example, manganese dioxide, is formed so as to be in close contact with the surface of the metal substrate 1 and to fill the recesses in the uneven surface of the metal substrate 1.
, a graphite layer 5 formed on this metal oxide layer 4, a cathode lead member 6 in which a portion of the graphite layer that has been baked in advance is embedded in the graphite layer 5, and a two-liquid layer formed by a dip. The first coating for coating with excellent moisture resistance properties is made of polyester epoxy resin, etc.
and a second insulating layer 8 formed using powdered epoxy resin or the like to increase mechanical strength.

Note that 9 is a protective coating for the anode lead member made of, for example, a silicone coating. That is, it prevents the anode lead member from being corroded by acid during etching or chemical formation. Therefore, this protective coating 9 is
The purpose can be achieved by providing the anode lead member 2 and the metal substrate 1 in a limited manner in the boundary area, but the dimensions of the metal substrate 1 are, for example, 1 mm in thickness, 4 mm in vertical width,
Since the width is extremely small, such as 4 mm, during mass production, a protective film 9 is formed on the underside of the metal substrate 1 to a depth of about 1 mm, as shown by the chain line 10 in FIG. 2, resulting in a reduction in capacity.

By the way, in the case where the cathode lead member 6 is directly bonded to the graphite layer 5 as shown in FIG.
The disadvantage was that the series resistance between the

Therefore, an object of the present invention is to provide a solid electrolytic capacitor in which a cathode lead member is embedded in a graphite layer, which can reduce series resistance and increase capacitance. be.

To achieve the above object, the solid electrolytic capacitor according to the present invention will be described with reference to the drawings showing the embodiments. A through hole 11 is provided in the through hole 11, and an anodic oxide film 3, a semiconductor metal oxide layer 4, and a graphite layer 5 are also provided on the wall surface of the through hole 11. The size of the through hole 11 was determined so that the surface side and the other main surface side were electrically connected, and the surface area of the anodic oxide film 3 was larger when the through hole 11 was provided than when it was not provided. It is characterized by this.

According to the present invention, the graphite layer embedded in the through-hole portion electrically couples the graphite layer on one main surface side of the metal substrate with the graphite layer on the other main surface side, and The series resistance up to the lead member is reduced, and tan δ is reduced. Further, since the through-hole portion is also used as an effective surface area for forming a capacitor, it is possible to increase the capacitance with the same external dimensions.

Embodiments of the present invention will be described below with reference to the drawings.

In the solid electrolytic capacitor according to this embodiment shown in FIGS. 3 to 6, a metal substrate 1 made of an aluminum plate is made into a special shape. That is, a through hole 11 is formed in the metal substrate 1 from one main surface 1a to the other main surface 1b, and the width W of the through hole 11 is twice the thickness of the anodic oxide film 3. The thickness of the through hole 11 is determined to be greater than or equal to the sum of twice the thickness of the semiconductor metal oxide layer 4 and the thickness of the graphite layer 5, and the size of the through hole 11 is determined to be greater than or equal to twice the thickness of the semiconductor metal oxide layer 4 and the thickness of the graphite layer 5. It is determined that the surface area of the anodic oxide film 3 formed when the through hole 11 is provided in the metal substrate 1 is larger than the surface area of the anodic oxide film 3 that is formed when the through hole 11 is provided in the metal substrate 1.

More specifically, the metal substrate 1 has a thickness of 1 mm, a vertical width a excluding the protrusion 12 of 3.5 mm, a horizontal width b of 4.5 mm,
The width of the through hole 11 is 0.7 mm, the depth f of the cut of this through hole 11 is 2 mm, and the through hole 1 is
Width c to 1 and width from right end to through hole 11
d is determined to be 1.9 mm, and the length e of the protruding portion 12 is determined to be 1 mm.

When making a capacitor using such a metal substrate 1, a silicone retention coating is provided below the portion of the metal substrate 1 indicated by the chain line 10 in the same manner as in FIG. 1 to protect the lead members 2. On this occasion,
Since the protrusion 12 is provided, it is possible to prevent a silicone protective film from being formed on the bottom surface 1d.

The manufacturing method of the electrolytic capacitor is the same as that shown in FIG. 1, in which the metal substrate 1 is electrolytically etched to provide an uneven surface, and then the anodic oxide film 3 and the semiconductor metal oxide layer 4 are formed in the same manner as shown in FIG. Form sequentially.
In this example, the graphite layer 5 on the semiconductor metal oxide layer 4 is formed of a first graphite layer 5a and a second graphite layer 5b, of which the first graphite layer 5a is a graphite suspension. The metal oxide layer 4 is immersed in the metal oxide layer 4 and then heated and dried. After the formation of the first graphite layer 5a is completed, a flat connecting portion 6a is formed by baking a thin graphite layer (not shown) onto the cathode lead member 6.
is brought into close contact with the first graphite layer 5a, and graphite is applied again and dried to form a second graphite layer 5b, and the bonding portion 6a is embedded in the first and second graphite layers 5a, 5b. state. Since the cathode lead member 6 cannot be mechanically bonded with graphite alone, the cathode lead member 6 is positioned and held in a predetermined position relative to the metal substrate 1 and anode lead member 2 using a jig. proceed. As is clear from FIGS. 3 and 6, the cathode lead member 6 includes a flat joint part 6a, a lead member 6b extending along a line parallel to the flat joint part 6a, and a bent part 6c interposed between them. It consists of After embedding the cathode lead member 6 into the graphite layer 5, a first insulating layer 7 and a second insulating layer 8 similar to those shown in FIG. 1 are formed. At this time, the bent portion 6c of the cathode lead member 6 is embedded in the first and second insulating layers 7 and 8.
When the second insulating layer 8 is formed of epoxy resin, the element is completed by curing it,
It becomes possible to remove the cathode lead member 6 from the jig. Anode lead member 2 and cathode lead member 6
If it is in the form of a lead frame, it is made into an independent element by cutting it.

In the case of this embodiment, also in the through hole 11,
As illustrated in FIG. 5, a layer 13 consisting of an anodic oxide film 3 and a semiconductor metal oxide layer 4 is formed, and a graphite layer 5 is further formed to fill the remaining portion. Therefore, the graphite layer on one main surface 1a side of the metal substrate 1 and the other main surface 1b
is electrically coupled to the graphite layer through the through hole 11, the electrical resistance from the surface of the semiconductor metal oxide layer 4 to the cathode lead member 6 is reduced, and tan δ is reduced. Also, the through hole 11
Since the effective surface area of the capacitor is increased by providing the silicone protective coating, and the effective surface area of the capacitor is increased by reducing the area where the silicone protective coating is provided, the capacitance also increases.

For comparison, the dimensions of the conventional substrate 1 in FIG. 2 are 4.5 mm in length, 4.5 mm in width, and 1 mm in thickness, and the width of the silicone protective coating 9 up to the chain line 10 is 0.9 mm.
When we measured the capacitance and tan δ of the capacitor of this example constructed using the substrate 1 of FIG. The capacity of is 0.32μ
F, whereas the capacitance of the capacitor in this example was 0.335 μF. In addition, the tan δ of the conventional capacitor at 1 kHz is 3.1, while the tan δ of the capacitor in this example is 2.6, and at 120 Hz
The tan δ of the conventional capacitor at 10 kHz is 1.2, whereas the tan δ of the capacitor of this example is 1.1, and the tan δ of the conventional capacitor at 10 kHz is 1.2.
8.6, whereas the tan of the capacitor in this example is
δ was 7.8.

FIG. 7 shows a metal substrate 1 according to another embodiment of the present invention. In this embodiment, through hole 1
1 is formed so that the entire circumference thereof is surrounded by the substrate 1. The thickness of the substrate 1 is 1 mm, the vertical width a is 3.5 mm, the horizontal width b is 4.5 mm, the length e of the protrusion 12 is 1 mm, the width c of the protrusion 112 is 1 mm, and the width w of the through hole 11 is 0.7.
mm, and the length f of the through hole 11 is 2 mm. Even if such a substrate 1 is used, a capacitor substantially similar to the embodiments shown in FIGS. 3 to 6 can be obtained, and the same effects can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be further modified. For example, a plurality of through holes 11 may be provided.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view illustrating a conventional solid electrolytic capacitor, Fig. 2 is a front view of a metal substrate of the capacitor shown in Fig. 1, and Fig. 3 is a metal substrate of a solid electrolytic capacitor according to an embodiment of the present invention. 4 is a sectional view of the portion corresponding to the - line in FIG. 3, FIG. 5 is a sectional view of the portion corresponding to the - line in FIG. 3, and FIG. 6 is a perspective view of the cathode lead member. , FIG. 7 is a front view of a metal substrate according to another embodiment. In the symbols used in the drawings, 1 is a metal substrate, 2 is an anode lead member, 3 is an anodic oxide film, 4 is a semiconductor oxide layer, 5a is a first graphite layer, and 5b is a second graphite layer. 6 is a cathode lead member, 7 is a first insulating layer, 8 is a second insulating layer, and 11 is a through hole.

Claims (1)

[Claims for Utility Model Registration] A metal substrate 1 on which an anodic oxide film can be formed, an anode lead member fixed to the metal substrate 1, and an anodic oxide film 3 formed on the outer peripheral surface of the metal substrate 1.
, a semiconductor metal oxide layer 4 formed on the anodic oxide film 3, a graphite layer 5 formed on the semiconductor metal oxide layer 4, and the metal substrate 1.
The graphite layer 5 is covered with a cathode lead member partially embedded in the graphite layer 5, and a part of the anode lead member and the cathode lead member exposed on one main surface side of the graphite layer 5. In a solid capacitor consisting of insulating coating layers 7 and 8 surrounding each other, the metal substrate 1 is provided with a through hole 11 extending from one main surface 1a to the other main surface 1b; One and the other main surfaces 1a, 1
an anodic oxide film 3 also on the wall surface of the through hole 11 so as to be continuous with the anodic oxide film 3, the semiconductor metal oxide layer 4 and the graphite layer 5 on b;
When the semiconductor metal oxide layer 4 and the graphite layer 5 are provided, and the surface area of the anodic oxide film 3 is larger than the surface area of the anodic oxide film 3 when the metal substrate 1 is provided with the through holes 11, the metal substrate 1 is provided with the through holes 11. A solid electrolytic capacitor characterized in that the size of the through hole 11 is determined so that the surface area of the anodic oxide film 3 becomes large.