JPS6135691B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for packaging a solid electrolytic capacitor, and in particular to improving the coverage of the root portion of a specific external lead member with a resin material when a water-repellent coating is formed on the external lead member. be.

Generally, this type of solid electrolytic capacitor is
As shown in the figure, a metal wire having a valve action is attached in advance to a capacitor element A which is formed by press-molding metal powder having a valve action into a cylindrical shape and sintering the anode lead B.
The first external lead member C is welded to the lead-out portion of the anode lead B, and the second external lead member D is soldered to the electrode lead-out layer E formed on the circumferential surface of the capacitor element A. After that, the entire circumferential surface of the capacitor element A is covered with a resin material F.

By the way, the resin material F of the capacitor element A
The coating is carried out, for example, by a dipping method as shown in FIG. That is, as shown in FIG. 1A, first, the capacitor element A is immersed in a thixotropic resin material F' to a level such that it is completely immersed. Usually, this resin material F' has a high viscosity of 20,000 CPS or more, so the wettability of the resin material F' to the capacitor element A is poor immediately after immersion.
The resin material F' is not applied to the top surface of the resin material F'. Therefore, the immersion level of the capacitor element A is subsequently made deeper, as shown in FIG. Then, the entire circumference of capacitor element A is made of resin material.
completely covered by F′. After pulling up the capacitor element A from the resin material F',
The exterior is completed by heat treatment.

However, when pulling up capacitor element A from resin material F',
The immersion level in the resin material F' is deeper than necessary, and the resin material F' existing between the first and second external lead members C and D hangs down. The external lead members C and D are made of resin material.
F' is deposited thinly, as if it were creeping up, and the appearance characteristics are significantly impaired. As well,
As shown in FIG. 3, when mounting on a printed board, the creeping up resin material G protrudes to the back surface of the printed board H, so the first and second external lead members C, D and the printed conductor are This also impairs the reliability of soldering.

On the other hand, as shown in Figure 2a, if the immersion time of the capacitor element A into the resin material F' is made long enough, the liquid level of the resin material F' will gradually rise until it reaches the position indicated by the dotted line in the figure. Return until. Therefore, if the capacitor element A is pulled up at this point, the first and second external lead members C and D
The creeping up of the resin material F' against the printed board H can be suppressed to a level that does not pose a practical problem.
However, it has the disadvantage of significantly reducing workability, and has not yet been put into practical use.

Therefore, various solutions have been proposed in the past. For example, in Japanese Patent Application Laid-Open No. 55-145328, prior to coating a component body with a plurality of external lead members extending in the same direction by immersion in a resin material, By immersing the component body in a chlorinated hydrocarbon solution in which hydrocarbons or higher fatty acids are dissolved, so that the external lead member is immersed,
A method for packaging electronic components includes forming a water-repellent coating on the component body and external lead members, and then immersing only the component body in a solvent such as trichloroethylene trichloroethane to remove the coating from undesired areas. Disclosed.

According to this method, even if the immersion level of the component body into the resin material is deep as shown in FIG. As a result, the resin material is repelled and unwanted creep-up and adhesion can be effectively suppressed.

By the way, when this method is applied to, for example, the solid electrolytic capacitor described above, it is possible to effectively suppress the creeping up and adhesion of the resin material F to the first and second external lead members C and D. As shown in FIG. 4, for example, the root portion of the external lead member D of No. 2 is insufficiently covered with the resin material F, resulting in a problem that not only the appearance but also the moisture resistance is significantly impaired.

To explain this point in detail, when the capacitor element A is immersed in the resin material F' and pulled up, the resin material F' existing between the first and second external lead members C and D hangs down. In particular, since the first external lead member C has a bent portion in the vicinity of the top surface of the capacitor element A, the resin material F' can be physically held in this portion. This can suppress the sagging to some extent.

However, since the second external lead member D has a straight shape, it has no function of preventing the resin material F' from hanging down. For this reason, together with the water-repellent effect of the water-repellent coating K, the root portion of the second external lead member D is not sufficiently covered with the resin material F, which not only impairs the appearance characteristics but also damages the second external lead member D. Due to the bending force acting on the external lead member D, cracks may occur in the resin material F at the base of the external lead member D, and the moisture resistance will be significantly impaired.

This problem can be solved by increasing the number of times the capacitor element A is immersed in the resin material F', but increasing the number of times of heat treatment not only impairs the leakage current characteristics, but also
In some cases, more resin material F is deposited on the circumferential surface than necessary, and the exterior form tends to become larger. Therefore, even if the capacitor element is made smaller in order to make the capacitor smaller, there is a problem in that sufficient effects cannot be obtained.

In view of these points, the present invention has been proposed to improve the top surface portion of the capacitor element, including the root portion of the second external lead member, without impairing the effect of preventing the resin material from creeping up to the first and second external lead members. The present invention provides a method for packaging a solid electrolytic capacitor that can reliably cover the solid electrolytic capacitor with a resin material, and one packaging method will be described below with reference to FIGS. 5 to 10.

First, as shown in FIG. 5, a metal wire having a valve action is planted in advance as an anode lead 2 on a capacitor element 1 which is made by press-forming metal powder having a valve action into a cylindrical shape and sintering it. An L-shaped first external lead member 3 is attached to the lead-out portion 2a of the anode lead 2.
are welded so that the bent portions 3a intersect. Then, one end 4a of the straight second external lead member 4 is soldered to an electrode lead layer 5 formed on the circumferential surface of the capacitor element 1 via an oxide layer and a semiconductor layer to form a capacitor structure.
Note that the first and second external lead members 3 and 4 are led out in the same direction.

Next, as shown in FIG.
Immerse so that the welded portion with the external lead member 3 is immersed. After the capacitor element 1 is pulled up, the undesired resin material adhering to the circumferential surface of the capacitor element 1 except for the top surface is removed using a cleaning liquid, and the second The top surface portion of the capacitor element 1 including the root portion of the external lead member 4 is covered with a first resin material 6.

Next, this capacitor structure is immersed in a liquid water-repellent material so that the first resin material 6 is completely immersed. After pulling up, heat treatment is performed to form a water-repellent coating 7 on the capacitor element 1, the first and second external lead members 3 and 4, and the first resin material 6, as shown in FIG. be done.

Next, as shown in FIG. 9, this capacitor structure is completely immersed in a second resin material 8' having thixotropic properties, and the first resin material 6 is completely immersed in the first and second external lead members. The liquid is immersed sufficiently deep so that the water repellent coatings 7 of Nos. 3 and 4 are exposed at the same level or slightly exposed to the liquid level of the second resin material 8'. As a result, the entire circumferential surface of the capacitor element (first resin material 6) is wetted with the second resin material 8' in a short time, but the area near the liquid level of the first and second external lead members 3 and 4 is wetted with the second resin material 8'. Now, the resin material 8' is in a repelled state. Then, when the capacitor structure is pulled up from the second resin material 8', the second resin material 8' existing between the first and second external lead members 3 and 4 is immersed in the second resin material 8' depending on the immersion depth. At the same time as the second resin material 8' that is in contact with the first and second external lead members 3 and 4 is repelled, the second resin material 8' also hangs down. Thereafter, by heat treatment, the main portion including the capacitor element 1 is transformed into a second resin material 8, as shown in FIG.
to complete the exterior.

In this way, the first and second external lead members 3, 4
Since the water-repellent coating 7 is formed on desired portions of the capacitor structure by a dipping method, when the capacitor structure is dipped into the second resin material 8' and pulled up, the first and second external lead members 3, The second resin material 8' attached to the undesired portions of the first and second external lead members 3 and 4
Together with the second resin material 8' existing in between, it is repelled and hangs down an appropriate amount. For this reason, it is possible to almost eliminate the creeping up and adhesion of the second resin material 8 to the first and second external lead members 3 and 4, and when mounting the first and second external lead members on a printed board. Soldering defects for printed conductors 3 and 4 can be significantly reduced.

Furthermore, prior to the formation of the water-repellent coating 7, the first resin material 6 is applied to the top surface of the capacitor element 1, including the root portion of the second external lead member 4. Even if the second resin material 8' is immersed in the second resin material 8' and pulled up, the second resin material 8' between the first and second external lead members 3 and 4 does not hang down more than necessary. Therefore, the root portion of the second external lead member 4 is reliably covered with the second resin material 8', and not only the appearance characteristics but also the moisture resistance can be significantly improved.

Furthermore, after applying a first resin material 6' to the top surface of the capacitor element 1 so as to cover the welded portion between the anode lead 2 and the first external lead member 3, the circumferential surface of the capacitor element 1 is Since the first resin material 6' applied to the portion is removed, the thickness of the second resin material 8 covering the circumferential surface of the capacitor element can be made sufficiently small. Therefore,
The exterior form of the capacitor can be effectively miniaturized.

Next, specific examples will be described. A 0.5φmm tantalum wire (anode lead) was planted in advance on a capacitor element made by press-molding tantalum powder into a 3φ x 4mm column and sintering it, and bent it into an L shape.
The first external lead member of 0.5φmm is welded to the anode lead at a distance of 2.0mm from the top surface of the capacitor element, and a straight 0.5mm
A second external lead member of φmm is attached to the electrode extraction layer,
Solder it so that the distance from the first external lead member is 5 mm. Next, a capacitor structure is attached to a first resin material made by mixing powdered phenolic resin and alcohol at a weight ratio of 1:1.
Immerse and pull up the capacitor element so that the upper part 3.0 mm away from the top surface is at the immersion level. Then, this capacitor structure is immersed in alcohol so that the top surface of the capacitor element is not immersed, and the first resin material adhering to the circumferential surface of the capacitor element is cleaned and removed, and heat treated. Next, this capacitor structure was manufactured by Daikin Corporation under the trade name Daifree (FS-126).
immerse the first external lead member so that the upper part 5 mm away from the bent part is at the immersion level,
After pulling it up, it is heat-treated to form a water-repellent film of fluorine-based resin. Next, the capacitor structure was immersed in a second resin material made of epoxy resin having thixotropic properties and a viscosity of 40,000 CPS, so that the upper part 3 mm away from the bent part of the first external lead member was at the immersion level. After immersion and pulling, heat treatment is performed to obtain a tantalum solid electrolytic capacitor.

In this capacitor, the height of the epoxy resin creeping up to the first and second external lead members (height from the lowest position of the epoxy resin between the first and second external lead members) is average. The thickness was 0.1 mm, and there were no problems when mounting it on a printed board. Further, the root portion of the second external lead member was never undesirably exposed from the epoxy resin. Furthermore, the final coating with epoxy resin can be performed only once or twice, and the packaging form can be reduced by about 10 to 15% compared to conventional products with a water-repellent coating.

In addition, in the present invention, the capacitor element can be made of a plate material, a wire material, etc. in addition to metal powder, and when using metal powder, it can be made of a single material,
Alloys may also be used. Further, resin materials other than phenol resin and epoxy resin can be used as the first and second resin materials. In addition to fluorine-based resin, the water-repellent coating
It can also be formed from silicone resin, paraffin, etc.

As described above, according to the present invention, the top surface portion of the capacitor element including the root portion of the second external lead member can be removed without impairing the effect of preventing the resin material from creeping up to the first and second external lead members. can be reliably covered with a resin material, the appearance characteristics and moisture resistance can be improved, and the exterior form can be made smaller.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional solid electrolytic capacitor, Figure 2 is a side sectional view for explaining the resin packaging method, Figure 3 is a side sectional view showing how it is mounted on a printed board, and Figure 4 is a side sectional view of a conventional solid electrolytic capacitor. 5 to 10 are explanatory diagrams of the method of the present invention, and FIG. 5 is a side sectional view of the capacitor structure, and FIG. 7 is a side sectional view showing a state in which the capacitor structure is immersed in the first resin material, FIG. 7 is a side sectional view showing the state in which the first resin material is adhered to the top surface of the capacitor element, and FIG. 8 is a water repellent FIG. 9 is a side sectional view showing a state in which the coating is formed, FIG. 9 is a side sectional view showing a state in which the capacitor structure is immersed in the second resin material, and FIG. 10 is a side sectional view showing a state in which the exterior is completed. In the figure, 1 is a capacitor element, 2 is an anode lead, 3 is a first external lead member, 4 is a second external lead member, 5 is an electrode lead layer, 6, 6' is a first resin material, and 7 is a The water-repellent coating 8, 8' is a second resin material.

Claims (1)

[Claims] 1. An electrode lead layer is formed on the circumferential surface of a capacitor element made of a metal member having a valve action, from which a metal wire having a valve action is led out as an anode lead, and an electrode lead layer is formed on the circumferential surface of the capacitor element. A first external lead member having an L-shaped bent part is welded so that the bent part intersects with the leading part, and a second external lead member is led out in substantially the same direction as the first external lead member. immersing the capacitor structure in a liquid first resin material so that the welded portion of the anode lead and the first external lead member is immersed; After pulling it up,
a step of removing the first resin material adhering to the circumferential surface of the capacitor element except for the top surface portion; and a step of removing the first resin material adhering to the circumferential surface of the capacitor element except for the top surface portion of the capacitor element; a step of forming a water-repellent film on a desired portion by immersing the capacitor structure in a second resin material having thixotropic properties; An exterior packaging for a solid electrolytic capacitor comprising the step of immersing the external lead member so that the water-repellent coating is exposed to or equal to the liquid level of the second resin material to cover the main parts including the capacitor element. Method.