JPS6220684B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for packaging electronic components, and in particular, an object of the present invention is to reduce the creeping up and adhesion of a resin material to an external lead member in a solid electrolytic capacitor.

Generally, this type of solid electrolytic capacitor is
As shown in the figure, a metal wire having a valve action is attached to a capacitor element A made by press-molding and sintering a metal powder having a valve action, such as tantalum, niobium, or aluminum, into a cylindrical shape and an anode lead B. the first one on the protruding part of this anode lead B.
At the same time, the second external lead member D is soldered to the electrode lead layer E formed on the circumferential surface of the capacitor element A, and then the main part including the capacitor element A is covered with resin. It is covered with 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, first, as shown in FIG.
F′ to a level such that it is completely immersed. Usually, this resin material F' has a high viscosity, for example, 20,000 CPS or more, so the wettability of the resin material F' to the capacitor element A is poor immediately after immersion, and the top surface of the resin material F' is not deposited. Therefore, as shown in FIG.
Deepen the immersion level. Then, the entire circumferential surface of the capacitor element A is completely covered with the resin material F'. The capacitor element A is then pulled up and hardened to complete the exterior packaging.

However, when pulling up capacitor element A from resin material F',
The immersion level in the resin material F' is deeper than necessary, and in order to prevent the resin material F' existing between the first and second lead members C and D from sagging, the first and second lead members The resin material F' is thinly applied to the external lead members C and D, so that the resin material F' creeps up on the outer lead members C and D, and the appearance characteristics are significantly impaired. Not only that, but also, for example, when mounting on a printed board as shown in Figure 3,
Since the creeping resin material G protrudes to the back surface of the printed board H, the reliability of soldering between the first and second external lead members C and D and the printed conductor is also significantly impaired.

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 sufficiently long, the liquid level of the resin material F' will gradually rise.
Eventually, it returns to the position shown by the dotted line. Therefore, if the capacitor element A is pulled up at this point, the creeping of the resin material onto the first and second external lead members C and D can be suppressed to a level that does not pose a practical problem, and it is possible to prevent the resin material from creeping up onto the above-mentioned printed board. Although this method can completely solve the problems encountered during implementation, it has the drawback of significantly lowering workability, and has not yet been put into practical use.

In view of these points, the present invention provides a method for packaging electronic components that can effectively suppress the creeping of resin material onto external lead members without impairing workability. The packaging method will be explained with reference to FIG.

First, as shown in Figure a, a metal wire having a valve action is planted in advance as an anode lead 2 in a capacitor element (component body) 1 which is made by press-molding metal powder having a valve action into a cylindrical shape and sintering it. The protruding portion 2a of the anode lead 2 has a first portion bent in an L shape.
The external lead members 3 are crossed and welded. One end 4a of the second external lead member 4 is then 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. Note that the first and second external lead members 3 and 4 are led out in the same direction. Next, as shown in Fig. b, the capacitor element 1 has a viscosity of 1000~
The welded portion between the anode lead 2 and the first external lead member 3 is immersed in the first resin material 6' set at 10,000 CPS. Then, since this resin material 6' has a low viscosity and has good wettability with respect to the capacitor element 1 and the first and second external lead members 3 and 4, it reaches the desired level almost immediately after dipping. It can be covered with the first resin material 6'. Next, capacitor element 1
When it is pulled up from the first resin material 6', the main portion including the capacitor element 1 is covered with the first resin material 6', as shown in FIG. Next, figure d
As shown in FIG.
The same resin material with a viscosity of 20,000 CPS or more,
The second resin material 7' is preferably set to 50,000 CPS or more, and is immersed at approximately the same level as the immersion level in the first resin material 6'. Then, the first resin material 6 covering the capacitor element 1
Since the second resin material 7' is in an uncured state, the second resin material 7' quickly wets the first resin material 6, and the second resin material 7' is reliably coated to a desired level. After that, as shown in FIG.
The exterior is completed by pulling it up and heating it to harden it.

In this way, capacitor element 1 has a viscosity of
After being primarily covered with the first resin material 6' having a viscosity of 1,000 to 10,000 CPS, the second resin material 7' having a viscosity of 20,000 CPS or more is used as the secondary covering, so that the first and second external lead members 3, The amount of resin material creeping up relative to No. 4 can be suppressed to a level that does not cause any practical problems. Specifically, when the uncured first resin material 6 is immersed in the highly viscous second resin material 7' after the primary packaging, the wetting of the second resin material 7' with respect to the first resin material 6 may occur. Because of its good properties, it can be completely wetted and completely covered in a short time after dipping. Therefore, a desired portion of the capacitor element 1 can be reliably covered without making the immersion level of the capacitor element 1 into the second resin material 7' deeper than necessary. For this purpose, the first and second
A resin material 7' located between the external lead members 3 and 4 of
There is also less sagging and creeping up and adhesion can be minimized.

Moreover, when the capacitor element 1 is immersed in the second resin material 7', the time required for the entire capacitor element to be covered with the second resin material 7' is extremely short, so that the workability of the secondary exterior is reduced. It can be significantly improved.

Furthermore, as mentioned above, since the resin material can be prevented from creeping up and adhering to the first and second external lead members 3 and 4, for example, when mounting on a printed circuit board, the creeping up resin material can be prevented from adhering to the back surface of the printed board. Since there is no protrusion, the first and second external lead members 3, 4 and the printed conductor can be reliably soldered.

Next, specific examples will be described. A capacitor element is made by press-molding tantalum powder into a cylinder with a diameter of 3 mm and a height of 4 mm and sintering it.
Plant a 0.5φmm tantalum wire (anode lead),
The first external lead member bent into an L shape is used as the anode lead, 1.5 mm from the top of the capacitor element.
At the same time, the second external lead member is soldered to the electrode extraction layer so that the distance from the first external lead member is 5 mm. Next, this capacitor element is immersed in a first resin material (epoxy resin) whose viscosity is set to 5000 CPS to provide a primary coating. Next, the second resin material (epoxy resin) whose viscosity was set to 50,000 CPS was immersed at almost the same level as the immersion level in the first resin material, and the second resin material was coated. , the creeping height to the second external lead member (the height from the lowest position of the resin material between the first and second external lead members) is 0.5 mm on average, and the height to the printed board is 0.5 mm. There were no problems at all during the implementation. However, in the conventional packaging method using only secondary packaging, the height was 1 to 3 mm.

Note that the present invention is not limited to the above-mentioned embodiments; for example, it is desirable that the first and second resin materials are of the same type, but they may be of different types; The packaging can also be done by immersing it three or more times in resin materials with different viscosities. The component body can also be immersed in the second resin material after the first resin material has hardened. Furthermore, electronic components can be applied not only to solid electrolytic capacitors but also to general capacitors, resistors, coils, etc.

As described above, according to the present invention, it is possible to significantly suppress the creeping up and adhesion of the resin material to the external lead member without sacrificing workability, and for example, when mounting on a printed board, the reliability of soldering can be improved. can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a front sectional view of the conventional example, Figure 2 is a front sectional view of the main part to explain the packaging method, Figure 3 is a sectional view of the main part showing the mounting state on the printed board, and Figure 4 is the main part of the main part. FIG. 2 is a front cross-sectional view for explaining the invention method. In the figure, 1 is a component body, 3 and 4 are external lead members, 6 and 6' are first resin materials, and 7 and 7' are second resin materials.

Claims (1)

[Claims] 1. A step in which a component body having a plurality of external lead members extending in the same direction is immersed in a first resin material having a viscosity of 1,000 to 10,000 CPS to provide primary sheathing; 1. A method for packaging an electronic component, comprising the step of immersing it in a second resin material to a level substantially equal to the level of immersion in the first resin material to perform secondary packaging.