JPS6132806B2 - - 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
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, 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. Normally, this resin material F′ has a high viscosity, for example, 20,000 CPS or more, so immediately after immersion, the resin material
The wettability of F' to the capacitor element A is poor, and the resin material F' is not coated on the top surface of the capacitor element A. Therefore, the immersion level of the capacitor element A is subsequently made deeper, as shown in FIG. Then, the entire circumferential surface of the capacitor element A is completely covered with the resin material F'. and,
The packaging is completed by pulling up the capacitor element A and subjecting it to 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 coated thinly, as if it were creeping up, and the appearance characteristics are significantly impaired. As well,
As shown in FIG. 3, when mounting on the printed board H, the creeping resin material G protrudes to the back surface of the printed board H. The reliability of soldering with conductors is also 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 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 drawback of significantly reducing workability, and has not yet been put into practical use.

Therefore, the present applicant first applied a water-repellent coating to the component body and the external lead members before immersing and sheathing the component body including a plurality of external lead members extending in the same direction with a resin material having thixotropic properties. We have proposed a method for packaging electronic components, which is characterized in that it is formed by dipping it into a water-repellent member.

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 prevent the resin material F from creeping up and adhering to the first and second external lead members C and D. Because the resin material F at the root part of D is repelled more than necessary by the water-repellent effect of the water-repellent coating,
There is a problem that undesired portions of the second external lead member D are exposed and the appearance characteristics are significantly impaired.

In this regard, in detail, the first external lead member C
Since one end is bent into an L shape, the resin material F' can be physically held between the bent part and the capacitor element A even if a water-repellent coating is formed. 1 external lead member C
The root portion of the resin material F' is not undesirably exposed. However, since the second external lead member D is formed in a substantially straight shape, it cannot be made of resin material like the first external lead member C.
Poor retention effect on F′. Therefore, combined with the water-repellent effect of the water-repellent coating, the resin material F' is repelled more than necessary, resulting in the root portion of the second external lead member D being exposed undesirably. Appearance characteristics are significantly impaired. Furthermore, since the coating thickness of the resin material F at the root portion of the second external lead member D is locally thin, when an expansion force is applied to the second external lead member D, the resin material F There is also the problem that cracks easily occur and moisture resistance is impaired.

In view of these points, the present invention provides a method for packaging electronic components that can effectively prevent not only the resin material creeping up and adhering to the external lead member, but also the undesirable exposure of the resin material of the external lead member. An example of application to a solid electrolytic capacitor will be described below with reference to FIGS. 4 to 8.

First, as shown in FIG. 4, a metal wire having a valve action is implanted in advance as an anode lead 2 into 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 first external lead member 3, which is formed in an L shape, is welded to the lead-out portion 2a of the anode lead 2 so that the bent portions 3a intersect. Then, one end 4a of the second external lead member 4 formed in a straight shape 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 graphite layer. Note that the first and second external lead members 3 and 4 are led out in the same direction. next,
The capacitor element 1 is made of a first resin material having thixotropic properties, and the first external lead member 3 is made of a first resin material having thixotropic properties.
It is immersed so that substantially the lower surface of the bent portion 3a is at the immersion level. Then, after being pulled up, the capacitor element 1 is coated with the first resin material 6 by heat treatment, as shown in FIG. Next, the capacitor element 1 is made into a water-repellent member, and the first and second external lead members 3 and 4 are made into a water-repellent member.
Immerse at a deeper level than the immersion level for the resin material. After pulling up, heat treatment is applied to the first resin material 6 covering the capacitor element 1 and the first and second external lead members 3 and 4 derived therefrom.
As shown in the figure, a water-repellent coating 7 is formed. Next, as shown in FIG. 7, this capacitor element 1 is coated with a second resin material 8' having thixotropic properties so that the upper ends of the water-repellent coatings 7 on the first and second external lead members 3 and 4 are coated with liquid. Immerse it deep enough so that it slightly protrudes from the surface. Then, the second resin material 8' gets wet on the entire circumferential surface of the capacitor element 1 in a short time, but the second resin material 8' gets wet near the liquid level of the first and second external lead members 3 and 4. ′
will be in a flipped state. Next, when the capacitor element 1 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 hangs down, and at the same time , second
The second resin material 8' that is in contact with the external lead members 3 and 4 also sag. Thereafter, by heat treatment, a coating layer 8' made of a second resin material is formed as shown in FIG. 8, thereby completing the exterior packaging.

In this way, the first and second external lead members 3 and 4
Since the water-repellent coating 7 is formed on desired portions of the capacitor element 1 by the dipping method, when the capacitor element 1 is dipped in the second resin material 8' and pulled up, the first and second external lead members 3 , 4 hangs down in an appropriate amount together with the second resin material 8' present between the first and second external lead members. Therefore, it is possible to almost eliminate the second resin material 8' from creeping up and adhering to the first and second external lead members 3 and 4, and when mounting it on a printed board.
Failures in soldering of the first and second external lead members 3 and 4 to the printed conductor can be significantly reduced.

In addition, the capacitor element 1 is coated with a water-repellent coating 7.
Prior to forming the first resin material 6 having thixotropic properties, the first resin material 6 having thixotropic properties is applied so that the space existing between the top surface of the capacitor element 1 and the bent portion 3a of the first external lead member 3 is removed as much as possible. Therefore, when the capacitor element 1 is pulled up from the state shown in FIG. ′ hangs down together with the second resin material 8 ′ existing between the first and second external lead members, but does not hang down excessively. For this reason, in particular, even if the second external lead member 4 is formed in a straight shape, the root portion thereof will not be undesirably exposed from the coating layer 8, and the appearance characteristics can be significantly improved. .

Next, specific examples will be described.

Example 1 A tantalum wire (anode lead) of 0.5φmm was installed in advance in a capacitor element made by press-forming tantalum powder into a cylinder shape of 3 mm in diameter and 4 mm in height and sintering it, and bent it into an L shape. The first wire diameter is 0.5φmm.
An external lead member is welded to the anode lead so as to be spaced 1.5 mm from the top surface of the capacitor element, and a second external lead member having a wire diameter of 0.5 φ mm and formed in a straight shape is welded to the electrode lead layer. Solder it so that the distance from the first external lead member is 5 mm. Next, this capacitor element is immersed in an epoxy resin (impregnating agent) having a viscosity of 500 CPS so that the top surface of the capacitor element is immersed to a depth of 1 mm, and after the inside is sufficiently impregnated, heat treatment is performed. Next, the capacitor element is made of epoxy resin (first resin material) with a viscosity of 20,000 CPS and thixotropic properties.
The first external lead member is immersed so that the bent lower surface thereof is at the immersion level. After pulling, heat treatment is performed. Next, replace the capacitor element with the product name Daifree (FS-126) manufactured by Daikin Corporation.
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 coating of a fluorine-based compound. Next, the capacitor element is immersed in an epoxy resin (second resin material) having a viscosity of 40,000 CPS and thixotropic properties so that the upper part 4 mm away from the bent part of the first external lead member is at the immersion level. , After pulling, heat treatment is performed to obtain a tantalum solid electrolytic capacitor.

In this capacitor, the height of the second resin material rising to the first and second external lead members (height from the lowest position of the resin material existing between the first and second external lead members) was within 0.5 mm, and no trouble occurred during mounting on a printed board. Moreover, no undesirable exposure of the second resin material at the root portion of the second external lead member was observed.

Example 2 Using the capacitor element of Example 1, after impregnating it with epoxy resin, the capacitor element was
℃ and immersed in epoxy resin powder (first resin material) having a flat floating surface so that the immersion level is 1 mm above the top surface of the capacitor element. After pulling, heat at 150°C for 1 hour to harden. Thereafter, a tantalum solid electrolytic capacitor is obtained by processing in the same manner as in Example 1.

In this capacitor, there was no creeping of the second resin material onto the first and second external lead members, and no undesirable exposure of the root portion of the second external lead member was observed. Furthermore, since the adhesion level of the epoxy resin powder becomes constant, it is expected that workability will be improved.

Example 3 First and second external lead members formed in a straight shape are soldered to the external electrodes of a 5.7 x 5.3 x 1.7 mm multilayer ceramic capacitor chip. Next, the capacitor chip is immersed in an epoxy resin having a viscosity of 30,000 PCS and thixotropic properties so that the top surface of the chip is at the immersion level, and after being pulled out, it is heated. Next, the capacitor chip was immersed in the Daifree (FS-126) of Example 1 so that the immersion level was at a distance of 4 mm above the top surface of the chip, and after being pulled out, it was heated. Next, the capacitor chip is immersed in an epoxy resin with a viscosity of 30,000 CPS and thixotropic properties so that the immersion level is at a distance of 3 mm from the top of the chip, and after being pulled out, heat treatment is performed to form a laminated ceramic capacitor. obtain.

In this capacitor, no undesirable exposure of the root portions of the first and second external lead members from the epoxy resin was observed. And the first,
Even if an expansion force is applied to the second external lead member,
No cracks occurred in the epoxy resin at the base.

In addition, in the present invention, the electronic components can be applied to solid electrolytic capacitors, multilayer ceramic capacitors, varistors, resistors, and the like. Although it is preferable to use the same resin material as the first and second resin materials, they can also be different types of resin materials. In addition to fluorine-based compounds, silicone oil, stearic acid, and the like may also be used as the water-repellent material.

As described above, according to the present invention, it is possible to effectively prevent not only the resin material from creeping up and adhering to the external lead member, but also the undesirable exposure of the external lead member from the resin material.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a conventional solid electrolytic capacitor, Fig. 2 is a side sectional view for explaining the packaging method, Fig. 3 is a side sectional view showing how it is mounted on a printed board, and Figs. FIG. 8 is an explanatory diagram of the method of the present invention, in which FIG. 4 is a side sectional view of a capacitor element, FIG. 5 is a side sectional view showing a state in which a coating layer of the first resin material is formed, and FIG. FIG. 7 is a side sectional view showing the state in which the water-repellent coating is formed, FIG. 7 is a side sectional view showing the state in which the capacitor element is immersed in the second resin material, and FIG. 8 is a side sectional view showing the state in which the exterior is completed. In the figure, 1 is a component body (capacitor element), 3 and 4 are external lead members, 6 is a first resin material, 7 is a water-repellent coating, 8' is a second resin material, and 8 is a coating layer.

Claims (1)

[Claims] 1. Covering the component body with a first resin material by immersing the component body including a plurality of external lead members extending in the same direction in a powder-like or thixotropic first resin material; forming a water-repellent coating on a first resin material and an external lead member exposed from the first resin material by immersing the component body in a water-repellent member in a manner that the outer lead member is immersed; A process of coating the main parts including the component body with the second resin material by immersing the main body in a second resin material having thixotropic properties so that the water-repellent coating portion of the external lead member is at the immersion level. A method for packaging an electronic component, comprising: