JP3433490B2 - Chip-shaped solid electrolytic capacitors - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip solid electrolytic capacitor. [0002] A conventional chip-shaped solid electrolytic capacitor is
As shown in FIGS. 4 and 5, the surface of a flat plate-shaped anode substrate 1 made of a valve metal such as aluminum, tantalum, or niobium having a dielectric oxide film layer 2 on the surface thereof except for a part serving as an anode portion is formed of a semiconductor. Solid electrolytic capacitor element 5 in which layer 3 and conductor layer 4 are sequentially laminated (hereinafter referred to as capacitor element)
Is formed, and this capacitor element 5 is connected to a lead frame 6.
a and 6b are opposed to each other with an interval, and
The anode part 7 and the conductor layer forming part 8 of the capacitor element 5 are mounted on a and 6b. [0003] The former is a welding 9 or the like, and the latter is a conductive material 10 such as silver paste or the like.
After being electrically and mechanically connected to b, the chip-shaped solid electrolytic capacitor is formed by sealing with an exterior resin.
The sealed solid electrolytic capacitor is required to satisfy electrical performance such as capacity and the like, and is a product that has passed a sampling test such as a load test and a moisture resistance test. In the above-described capacitor element, during the moisture resistance test, moisture enters from the lead frame and approaches the dielectric oxide film layer of the capacitor element. There was the disadvantage of increasing the value. In order to prevent such a drawback, it has been considered to cover the capacitor element with a water-resistant resin. However, there is a problem in workability and cost. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is to provide a solid electrolytic capacitor element having an anode part and a conductor layer forming part. In the chip-shaped solid electrolytic capacitor, the anode portion and one surface of the conductor layer forming portion are respectively mounted and joined to the protrusions of the lead frame having a pair of opposedly disposed protrusions. The chip-shaped solid electrolytic capacitor has a notch provided at the tip of the convex portion on the side where the anode portion of the lead frame is mounted, and the remaining portion to which the anode portion of the capacitor element is mounted and joined. . Hereinafter, the present invention will be described in detail. In the present invention, as the anode base having a valve action used as the anode of the solid electrolytic capacitor, any metal having a valve action such as aluminum, tantalum, and alloys using these as a substrate can be used. Examples of the shape of the anode substrate include a flat aluminum foil and plate. The dielectric oxide film layer provided on the surface of the anode substrate may be an oxide layer of the valve action metal itself provided on the surface portion of the valve action metal, or may be provided on the surface of the valve action metal foil. Alternatively, a layer of another dielectric oxide may be used, but a layer made of an oxide of the valve metal itself is particularly desirable. In the present invention, the anode portion is provided in one section of the end portion of the plate-shaped anode substrate having the dielectric oxide film layer formed on the surface, and the remaining dielectric oxide film other than the anode portion is provided. Although a semiconductor layer is formed on the layer, the type of the semiconductor layer is not particularly limited, and a conventionally known semiconductor layer can be used. Among them, a semiconductor layer composed of lead dioxide and lead sulfate, which was filed by the present applicant (JP-A-62-256423).
JP-A-63-51621) is preferable because the high frequency performance of the manufactured solid electrolytic capacitor is good. Also, a method of forming a complex of tetrathiotetracene and chloranil as a semiconductor layer (JP-A-62-2912)
No. 3) and a semiconductor layer composed of a conductive polymer compound obtained by doping a dopant into a 5-membered heterocyclic polymer compound (Japanese Patent Application Laid-Open No. 60-37114) are also examples. On the semiconductor layer, a conductive layer is formed by laminating a conventionally known conductive paste such as a carbon paste and / or a silver paste to form a conductive layer forming portion. In the present invention, if a resin layer portion is formed in advance in a spiral shape with an insulating resin at the interface between the above-described anode portion and the conductor layer forming portion, the semiconductor layer is formed when the semiconductor layer is formed. Can be obtained with a constant area and a small variation. Next, a method of connecting the capacitor element formed up to the conductor layer in this way to a pair of opposing lead frames will be described. FIG.
FIG. 5 is a plan view showing a state where the solid electrolytic capacitor element 5 is connected to a lead frame 6. In FIG. 1, a dielectric oxide film layer 2 is formed on the surface of an anode substrate 1, a semiconductor layer 3 is further formed thereon, and a conductive layer 4 is further formed thereon. And the conductor layer forming portion 8 are mounted and joined to the respective protruding portions 6a and 6b of the lead frame 6, but the anode portion 7 is provided with a notch portion 11 at the tip of the protruding portion 6a of the lead frame. It is mounted and joined to the remaining portion 12. FIG. 2 is a sectional view of FIG. In the present invention, the notch is provided at the tip of the projection on the side on which the anode of the lead frame is mounted, because the ingress of moisture from the anode side causes the conductor layer forming section to enter. This is because the effect of providing more cutout portions is greater than that of the above. Therefore, it is needless to say that a notch may be provided also at the tip of the lead frame convex portion on the side where the conductor layer forming portion is mounted, if necessary. The shape and size of the notch 11 provided at the tip of the protrusion 6a of the lead frame vary depending on the size of the solid electrolytic capacitor element 5, the size of the anode 7, the size of the protrusion of the lead frame, and the like. Although it cannot be determined unconditionally, the shape and size of the remaining portion 12 after the notch portion 11 is provided should be reduced as much as possible in order to alleviate the invasion of moisture from the outside after the sealing described later. It is important that the design is carefully examined in consideration of both the conflicting problem of the occurrence of a failure in the connection of the anode part due to the reduction of the diameter. FIG. 3 shows four examples of the shape of the notch 11 provided at the tip of the protrusion 6a of the lead frame, but the present invention is not limited to these. In FIG. 3, the anode part 7 of the capacitor element 5 is mounted on the remaining part 12 after the notch is provided. The number of cutouts provided in the lead frame protrusion 6a may be plural. In the capacitor element thus mounted on the lead frame, the anode portion is connected by welding, conductive paste, solder, or the like, while the conductor layer forming portion is connected by conductive paste, solder, or the like, and then connected to the lead. After sealing molding with a transfer molding machine or the like using an exterior resin 13 such as an epoxy resin while leaving a part of the frame, a convex portion of the lead frame is cut near the capacitor element to form a chip-shaped solid electrolytic capacitor. And Since the connection between the anode of the capacitor element and the lead frame is made at the remaining portion of the notch provided at the tip of the protrusion of the lead frame, moisture is radiated through the lead frame. Penetration into the body oxide layer is mitigated. The present invention will be described below in more detail with reference to examples and comparative examples. Examples 1 to 4 Small pieces of a 45 μF / cm ² aluminum etching foil (hereinafter referred to as a chemical conversion foil) having a surface formed with a dielectric oxide film layer by a chemical conversion treatment in an aqueous solution of phosphoric acid and ammonium phosphate, 4 mm × 3 mm Was prepared. 1 from the end of this chemical foil
A part of 3 mm x 3 mm is used as an anode part with the remaining 3 mm x 3 mm.
The part m is immersed in a mixed solution of a 2.4 mol / l aqueous solution of lead acetate trihydrate and an aqueous solution of 4.0 mol / l ammonium persulfate and left at 60 ° C. for 20 minutes to obtain a semiconductor composed of lead dioxide and lead sulfate. A layer was formed. After performing these operations three times,
A carbon paste and a silver paste were sequentially laminated on the semiconductor layer to form a conductor layer, thereby producing a capacitor element. On the other hand, a separately prepared lead frame (material 42 alloy, solder plating, thickness 0.1 mm, size of protrusion: width 3.
(0 mm, the interval between the tips of the projections is 0.5 mm). One surface of the conductive layer forming portion was mounted, and the former was connected by welding and the latter was connected by silver paste. After that, transfer molding is performed using epoxy resin, and the outer dimensions are 7 mm x 4
A 3 mm × 3 mm chip-shaped solid electrolytic capacitor was produced. Examples 5 to 8 In Examples 1 to 4, a chemical conversion foil was immersed in a 2.0 mol / l aqueous solution of lead acetate trihydrate to form a semiconductor layer. Except for the lead dioxide formed
In the same manner as in Examples 1 to 4, chip-shaped solid electrolytic capacitors were produced. Comparative Example 1 In the same manner as in Example 1, except that the notch was not provided in the lead frame and the anode of the capacitor element was mounted and connected to the protrusion of the lead frame, the solid electrolytic capacitor was used in the same manner as in Example 1. A capacitor was manufactured. Table 2 shows the performance of the solid electrolytic capacitor immediately after being manufactured as described above and the performance of the capacitor after a humidity resistance test at 85 ° C. and 85% RH for 200 hours. In addition, each Example or Comparative Example is an average value of all numerical values n = 50 points. Although the content of the present invention has been specifically described above by taking a single-layer solid electrolytic capacitor as an example,
It goes without saying that the present invention can be applied to a laminated solid electrolytic capacitor. [Table 1] [Table 2] According to the chip-shaped solid electrolytic capacitor of the present invention, the anode of the capacitor element is provided with a notch at the tip of the projection of the lead frame and is connected to the remainder.
The increase in the capacity and the tan δ value after the moisture resistance test is suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a state where a solid electrolytic capacitor element is connected to a lead frame. FIG. 2 is a cross-sectional view showing a state where a solid electrolytic capacitor element is connected to a lead frame. FIG. 3 is a sectional view of another example showing a state where the solid electrolytic capacitor element is connected to a lead frame. FIG. 4 is a plan view showing a state in which a conventional chip-shaped solid electrolytic capacitor is mounted on a lead frame. FIG. 5 is a cross-sectional view showing a state where a conventional chip-shaped solid electrolytic capacitor is mounted on a lead frame. [Description of Signs] 1 Anode substrate 2 Dielectric oxide film layer 3 Semiconductor layer 4 Conductor layer 5 Solid electrolytic capacitor element 6a Protrusion 6b on the side on which anode part of lead frame is mounted Lead conductor layer forming part of lead frame The convex part 7 on the side on which is mounted The anode part 8 The conductor layer forming part 9 The welding 10 The conductive material 11 The notch part 12 The remaining part 13 The exterior resin

Claims (1)

(57) Claims 1. A solid electrolytic capacitor element having an anode portion and a conductor layer forming portion, wherein the anode portion and one surface of the conductor layer forming portion are arranged in a pair facing each other. In the chip-shaped solid electrolytic capacitor which is mounted on and bonded to the protrusion of the lead frame having the formed protrusion, a notch is formed at the tip of the protrusion on the side where the anode of the lead frame is mounted. Wherein the anode portion of the capacitor element is placed and joined to the remaining portion.