JPS6246056B2 - - 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 the capacitor element A is pulled up by the resin material F', the immersion level of the capacitor element A into the resin material F' is deeper than necessary, and the first and second external lead members C, D Because the resin material F' existing between them hangs down, the first and second 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 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 disadvantage 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, and as a result, the root portion of the second external lead member D is exposed undesirably, and the appearance characteristics are significantly impaired. It can be done. 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 9.

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 the electrode lead layer 5 formed on the circumferential surface of the capacitor element 1 via an oxide layer, a semiconductor layer, and a 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 heated to such an extent that the oxide layer is not damaged. Then, the first external lead member 3 is immersed in a low-viscosity resin impregnating agent while maintaining the heated state to such an extent that, for example, the bent portion 3a of the first external lead member 3 is not immersed. After the capacitor element 1 is sufficiently impregnated with the impregnating agent, the resin impregnated layer 6 is formed by pulling and heating the capacitor element 1, as shown in FIG. This resin-impregnated layer is formed in order to prevent pinholes from forming during coating formation, which will be described later.

Next, the capacitor element 1 is immersed in a water-repellent member at a position above the first and second external lead members 3 and 4, that is, at a deeper level than the immersion level for a second resin material, which will be described later. After pulling up, heat treatment is performed to form the impregnated layer 6 covering the capacitor element 1 and the first and second external lead members 3 and 4 derived therefrom, as shown in FIG. , a water-repellent coating 7 is formed.

Next, the capacitor element 1 is attached to a first resin material 8 that is compatible with a water repellent member (water repellent coating 7) at a position below the first and second external lead members, for example, at a position below the first external lead member. Bent portion 3 of member 3
Immerse so that a is the immersion level. The first resin material is preferably a nitrocellulose or acrylic low-viscosity resin using ethyl acetate, butyl acetate, amyl acetate, butanol, cellosolve, cyclohexane, toluene, or the like as a solvent. In this state, the water-repellent coating 7 that is in contact with the first resin material is dissolved by its solvent, and mixed or chemically bonded to each other at the contact boundary. After pulling up, heat treatment is performed to form a resin layer 8 on the surface of the water-repellent coating 7 of the capacitor element 1, as shown in FIG.

Next, as shown in FIG. 8, this capacitor element 1 is placed in a high-viscosity second resin material 9' having thixotropic properties at positions above and below the first and second external lead members 3 and 4. The water-repellent coating 7 is immersed sufficiently deep so that the upper end of the water-repellent coating 7 slightly protrudes from the liquid surface so that the immersion level is at the intermediate position between the two.
Then, the second resin material 9' gets wet on the entire circumferential surface of the capacitor element 1 in a short time, but the second resin material 9' gets wet near the liquid level of the first and second external lead members 3 and 4. ′ is flipped.

Next, when the capacitor element 1 is pulled up from the second resin material 9', the second resin material 9' existing between the first and second external lead members 3 and 4 hangs down, and at the same time , second external lead members 3, 4
The second resin material 9' that is in contact with the second resin material 9' also sag. Thereafter, by heat treatment, a covering layer 9 made of a second resin material is formed as shown in FIG. 9, thereby completing the exterior packaging.

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 element 1 by the dipping method, when the capacitor element 1 is dipped in the second resin material 9' and pulled up, the first and second external lead members 3 . For this purpose, first,
The creeping adhesion of the second resin material 9' to the second external lead members 3, 4 can be almost eliminated, and the printed conductors of the first and second external lead members 3, 4 can be easily removed when mounted on a printed board. This can significantly reduce soldering defects.

Further, the surface of the water-repellent coating 7 on the capacitor element 1 and the first and second external lead members 3 and 4 located in the vicinity thereof is coated with a resin made of a first resin material that is compatible with the water-repellent coating 7. The layer 8 is formed, but when the capacitor element 1 is immersed in the first resin material, the water-repellent coating 7 is dissolved by the solvent of the first resin material and mixed or combined with each other. Since the resin layer 8 is in a bonded state, the adhesion of the resin layer 8 to the water-repellent coating 7 can be sufficiently ensured, and the adhesion of the coating layer 9 to the resin layer 8 can also be improved.

Furthermore, since the resin layer 8 is formed on the surface of the water-repellent coating 7 other than the desired portions of the first and second external lead members 3 and 4 as described above, the capacitor element 1 is coated with the second resin material. 9', when the second resin material 9' is in contact with the first and second external lead members 3 and 4, the second resin material 9' that is in contact with the first and second external lead members 3 and 4 is the second resin material between the first and second external lead members. Although it hangs down with the material 9', it does not hang down excessively because the water-repellent action of the water-repellent coating 7 in the undesired portions is suppressed. For this reason, a sufficient coating layer 9 is formed at the root portion of the second external lead member 4, which not only improves the appearance characteristics but also significantly reduces the occurrence of cracks caused by external forces and improves moisture resistance. It can be improved.

Furthermore, before forming the water-repellent coating 7 on the capacitor element 1 and the first and second external lead members 3 and 4, the resin impregnated layer 6 made of an impregnating agent is formed on the capacitor element 1. The air trapped inside can be sufficiently discharged. For this reason, when forming the coating layer 9 of the second resin material 9' on the capacitor element 1, even if the capacitor element 1 is heat-treated, almost no trapped air is released to the outside through the resin material. Therefore, excellent appearance characteristics can be obtained without the occurrence of pinholes.

Next, specific examples will be described.

Example 1 A 0.5φmm tantalum wire (anode lead) was attached to a capacitor element made by press-molding and sintering tantalum powder into a cylinder with a diameter of 3mm and a height of 4mm.
A first external lead member with a wire diameter of 0.5φmm bent into an L shape is welded to the anode lead so as to be spaced 1.5mm from the top surface of the capacitor element, and a wire diameter of 0.5φmm is A second external lead member formed in a straight shape is soldered to the electrode lead-out layer so that the distance from the first external lead member is 5 mm. Next, after heating this capacitor element to 120℃, it is immersed in an epoxy resin impregnating agent with a viscosity of 500 CPS so that the top surface of the capacitor element is immersed to a depth of 1 mm, and the inside is impregnated to the desired extent. , pulled up and heat treated. In addition to the above-mentioned epoxy resin, the impregnating agent here may be an acrylic resin or the like, and a resin impregnating agent that can have a low viscosity is used. A resin impregnated layer 6 is formed.

Next, a water-repellent coating 7 is formed on the capacitor element including the main portion of the external lead member. Specifically, a fluorine compound in which a fluorine-based polymer is dispersed in a solvent, such as the product name "Daifree FS-126"
The first external lead member is immersed in tetrafluoroethylene commercially available as (manufactured by Daikin) so that the upper part 5 mm away from the bent part of the first external lead member is at the immersion level. That is, the component body is immersed to a position above the external lead member, which is on the upper end side of the resin-impregnated layer 6 and above the bent portion of the first external lead member 3. After pulling it up, it is heat-treated to form a water-repellent coating of a fluorine-based compound. Next, the capacitor element is made of a first resin material, such as acrylic resin (trade name "NeoCrystalline DI-").
1037" (manufactured by Saito Paint Co., Ltd.) so that the bent part of the first external lead member is at the immersion level. After pulling, the resin layer 8 made of a resin material compatible with the water-repellent coating 7 is baked at 120° C. for 1 hour.
is formed. Here, the upper end position of the resin layer 8 is at the above-mentioned immersion level at the lower position of the external lead member, which is a position spaced downward from the upper end position of the coating 7. Next, the condenser element is
The first external lead member was immersed in an epoxy resin (second resin material) having thixotropic properties at 40,000 CPS so that the upper part 4 mm away from the bent part was at the immersion level, and after being pulled up, it was heated. 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 on average, and no trouble occurred during mounting on a printed board. Furthermore, there was no undesired exposure of the second resin material at the root portion of the second external lead member, and no problem in appearance occurred.

Example 2 Instead of neocrystalline in Example 1
Made by NCG Far East Co., Ltd., the viscosity is
A capacitor element was immersed in 150 CPS acrylic resin (trade name: Metal Blating), pulled up, and baked at 85° C. for 21 hours. The same effect as in Example 1 was obtained.

Example 3 A straight external lead member is soldered to the external electrode of a 5.7 x 5.3 x 1.7 mm multilayer ceramic capacitor chip. When a multilayer ceramic capacitor was manufactured using the same members as in Example 1, no creeping up of the second resin material onto the external lead member occurred.

In addition, in the present invention, the electronic components can be applied to solid electrolytic capacitors, multilayer ceramic capacitors, varistors, resistors, and the like. In addition to fluorine-based compounds, silicone oil, stearic acid, and the like may also be used as the water-repellent material. Furthermore, the first resin material is not limited to nitrocellulose-based or acrylic-based resin materials using ethyl acetate, butyl acetate, amyl acetate, butanol, cellosolve, cyclohexane, toluene, etc. as a solvent, but can be used as a water-repellent material. An appropriate one can be used depending on the situation.

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. 9 is an explanatory diagram of the method of the present invention, Fig. 4 is a side sectional view of a capacitor element, Fig. 5 is a side sectional view showing a state in which an impregnated layer is formed on the capacitor element, and Fig. 6 is a side sectional view showing a state in which an impregnated layer is formed on the capacitor element. 7 is a side sectional view showing a state in which a resin layer is formed, FIG. 8 is a side sectional view showing a state in which the capacitor element is immersed in the second resin material, and FIG. The figure is a side sectional view showing the completed exterior state. In the figure, 1 is the component body (capacitor element), 3 and 4 are external lead members, 6 is an impregnated layer, and 7
8 is a water-repellent coating, 8 is a resin layer (first resin material),
9' is a second resin material, and 9 is a covering layer.

Claims (1)

[Claims] 1 Step of immersing a component body 1 having a plurality of external lead members 3 and 4 in a resin impregnating agent to form a resin-impregnated layer 6 on the component body, up to a position above the external lead member located on the upper end side of this impregnated layer. A step of immersing the component body in a water-repellent member to form a water-repellent coating 7, and applying an external lead to a first resin material that is compatible with the coating, the component body being positioned at a distance from the upper position to the lower side. The step of immersing the component to a lower position to form a resin layer 8, and the step of dipping this component body into a thixotropic second resin material, the intermediate position between the upper and lower positions of the external lead member being the immersion level. A method for packaging an electronic component, which includes the step of dipping the main part including the component body to form a coating layer 9.