JPS6251492B2 - - 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 resin material to external lead members in solid electrolytic capacitors. 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 made of a metal powder having a valve action such as tantalum, niobium, aluminum, etc., pressure-molded into a circular shape and sintered. 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 outer lead members C and D are coated with a thin layer of resin material F' that appears to be creeping up, and the appearance characteristics are significantly impaired. In addition, as shown in FIG. 3, when mounted on the printed board H, the creeping resin material G protrudes to the back surface of the printed board H, so that the first and second external lead members C , D and the conductor portion of the printed circuit board becomes difficult, resulting in the occurrence of soldering defects for this type of circuit component. 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. As a solution to such problems, Japanese Utility Model Application Publication No. 51-1756 proposes forming a water-repellent coating on the external leads of electronic components that has the property of repelling resin materials in the same way as water (hereinafter referred to as water-repellent). and Japanese Patent Publication No. 55-145328
It is disclosed in the publication No. For example, JP-A-55-
Publication No. 145328 discloses that prior to coating a component body with a plurality of external lead members extending in the same direction by dipping it in a resin material, a chain hydrocarbon or higher fatty acid represented by wax, stearic acid, paraffin, etc. is applied. By immersing the component body in a dissolved chlorinated hydrocarbon solution so that the external lead member is immersed, a film of chain hydrocarbon or higher fatty acid is formed on the component body and the external lead member, and then, A method for packaging an electronic component is disclosed, in which a film on an undesired part is removed by immersing the main part of the part in a solvent such as trichlorethylene or trichloroethane so that the desired part of the external lead member is not immersed. . According to this method, even if the immersion level of the component body into the resin material is deep as shown in FIG. , the resin material is repelled and undesirable 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 resin material F' from creeping up and adhering to the first and second external lead members C and D. Resin material F
A problem arises in that a large number of pinholes are formed on the surface and the appearance characteristics are significantly impaired. To elaborate on this point, since capacitor element A has a porous structure, when it is immersed in a chlorinated hydrocarbon solution in which chain hydrocarbons or higher fatty acids are dissolved, this solution penetrates into the deep layers of capacitor element A. Even the pores in the area are impregnated. However, although the solution impregnated in the surface layer of the capacitor element A can be easily removed by simply immersing the capacitor element A in a solvent for a short time, the solution impregnated in the deep layer cannot be easily removed in a short time. Therefore, even if the material is impregnated with an impregnating agent for the purpose of preventing the formation of pinholes, the remaining film in the deep layer has the effect of repelling the resin material in the same way as water repellent (hereinafter, this property is referred to as water repellency). Therefore, it is not possible to impregnate the product sufficiently. For this reason, the air contained in the pores in the deep layer expands thermally when the resin material F is heated and hardened, penetrates the resin material F, and is released to the outside, resulting in the formation of many pinholes. It is considered that On the other hand, increasing the number of times of immersion and covering twice with the first resin material and the second resin material was disclosed in Japanese Patent Application Laid-Open No.
105152 and Japanese Patent Application Laid-Open No. 51-85461, and is known to prevent the resin material from creeping up to the external lead member, the capacitor element A is immersed in a solvent for a long time to prevent the resin material from creeping up to the external lead member. It has also been proposed that the solution in the deep layer be removed as a countermeasure against pinholes. However, contrary to their expected effects, these methods reduce work efficiency by complicating and time-consuming work due to the repetition of different tasks, and insufficient equipment capacity when processing the same task for a long time.
Considering the industrial value of the effect of preventing creeping up, it is extremely difficult to apply it to mass production processes. In view of these points, the present invention provides a method for packaging electronic components that can effectively improve not only the creeping up of the resin material onto the external lead member but also the occurrence of pinholes in the resin material. It is. According to the present invention, the exterior coating treatment of a component body having an external lead is performed by first dipping a predetermined portion of the external lead in a water-repellent member that forms a water-repellent film, and then applying a wettable liquid resin ( The top surface of the component body is immersed in phenolic resin at the level of the water-repellent film formation area to cover the first resin material, and then a low viscosity (approximately 500 CPS) impregnating agent is applied to the phenolic resin. an impregnating treatment in which the pores of the first resin coating layer are impregnated, and finally the component body is immersed in the second resin material so that the water-repellent coating portion of the external lead is at the immersion level,
A method for packaging an electronic component is presented, which covers the main parts including the component body. The application to a solid electrolytic capacitor as an embodiment of the present invention 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 made into a water-repellent member, and the first and second external lead members 3 and 4 are
Immerse at a deeper level than the immersion level for the resin material. After being pulled up, a water-repellent coating 6 is formed on the capacitor element 1 and the first and second external lead members 3 and 4 by heat treatment, as shown in FIG. Next, the capacitor element 1 is immersed in a liquid first resin material that exhibits wettability to the water-repellent coating 6 so that the top surface of the capacitor element 1 is immersed. After pulling up, heat treatment is performed to form a coating layer 7 made of the first resin material on the water-repellent coating 6 on the circumferential surface of the capacitor element 1, as shown in FIG. In particular, when a phenolic resin is used as the first resin material, the coating layer 7 is formed to be relatively porous. Next, this capacitor element 1 is immersed in an impregnating agent having a low viscosity of about 500 CPS to the extent that the coating layer 7 is immersed. Then, the impregnating agent mainly affects the coating layer 7.
It is impregnated into the pores of. Incidentally, the impregnation of this impregnating agent into the deep layer of the capacitor element 1 is not carried out much due to the water-repellent action of the water-repellent coating 6. and,
After pulling, an impregnating agent 8 is formed on the surface of the coating layer 7 by heat treatment, as shown in FIG. Next, as shown in FIG. 8, this capacitor element 1 is coated with a second resin material 9' having thixotropic properties so that the upper ends of the water-repellent coatings 6 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 entire circumferential surface of the capacitor element 1 is wetted with the second resin material 9' in a short time, but the
The second resin material 9' is in a repelled state near the liquid level of the external lead members 3 and 4. 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 , the second resin material 9' in contact with the second external lead members 3 and 4 also sag. After that, by heat treatment, as shown in FIG.
A coating layer 9 made of a resin material is formed to complete the exterior packaging. In this way, the first and second external lead members 3, 4
Since the water-repellent coating 6 is formed on a desired portion 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 , 4 hangs down by an appropriate amount together with the second resin material 9' present between the first and second external lead members. Therefore, it is possible to almost eliminate the second resin material 9' from creeping up and adhering to the first and second external lead members 3 and 4, and when mounting 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. Further, the formation of the water-repellent coating 6 on the first and second external lead members 3 and 4 is performed on the first and second external lead members 3 and 4 together with the capacitor element 1 on the water-repellent member.
4 is also carried out by immersion, and in addition, the water-repellent coating 6 of the capacitor element 1 is not removed at all and is used as is, which improves work efficiency compared to conventional exterior packaging methods. It can be improved. Moreover, on the water-repellent coating 6 of the capacitor element 1, a first layer having wettability is formed on the water-repellent coating 6.
Since the coating layer 7 is formed of a resin material and is impregnated with an impregnating agent, the air contained in the deep part of the capacitor element 1 is isolated from the outside world by the coating layer 7 and the impregnated layer 8. be in a state of being For this reason, when forming the coating layer 9 of the second resin material on the capacitor element 1, even if the enclosed air expands thermally, it will not penetrate the second resin material and be released to the outside. , excellent appearance characteristics can be obtained without the occurrence of pinholes. 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 and having a wire diameter of 0.5φmm is welded to the anode lead at a distance of 1.5mm from the top surface of the capacitor element, and the wire diameter is 0.5φmm and is formed into a straight shape. The second external lead member is attached to the electrode lead layer,
Solder it so that the distance from the first external lead member is 5 mm. Next, this capacitor element was manufactured by Daikin Corporation under the trade name Daifree (FS-126).Polyperfluoroacrylate, which is commercially available as a mold release agent, was mixed with dichlorotetrafluoroethane.

It is immersed in a water-repellent member made of a fluorine-based compound dissolved in a solvent of [Formula] so that the upper part 5 mm away from the bent part of the first external lead member is at the immersion level, and after being pulled up, it is heated and treated with fluorine. Forms a water-repellent film of the compound. Next, the capacitor element is made of phenol resin (first resin material).
The capacitor element is immersed in the capacitor element so that the upper part of the capacitor element is 1.0 mm above the immersion level, and after being pulled up, it is heated to form a porous coating layer. Next, this capacitor element is immersed in an epoxy resin with a viscosity of 500 CPS to the same level as the phenol resin, and is impregnated into the coating layer.
After pulling, heat treatment is performed. After that, the capacitor element is coated with an epoxy resin (second resin material) having a viscosity of 30,000 CPS and thixotropic properties, and is inserted into the bent part of the first external lead member for 4 hours.
It is immersed so that the upper part separated by mm is at the immersion level, and after being pulled up, it is heat-treated 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) is on average 0mm (0.2~-
0.3 mm), and no trouble occurred during mounting on the printed board. However, in the conventional example in which no water-repellent coating was formed, creeping adhesion of 1 to 3 mm occurred, resulting in poor soldering. Moreover, no pinholes were observed in the coating layer made of the second resin material. This is thought to be due to the effect of the phenolic resin covering the capacitor element and the effect of the impregnating agent closing the pores of the phenolic resin. In addition, in the present invention, the electronic component can be applied not only to a solid electrolytic capacitor but also to a varistor, a resistor, and the like. Further, the water-repellent member and the first resin material are not limited to resins of fluorine-based compounds such as tetrafluoroethylene resin, trifluorochloroethylene resin, vinylidene fluoride resin, and phenol resins. As described above, according to the present invention, it is possible to suppress the creeping up and adhesion of the resin material to the external lead member by a simple method to the extent that there is no practical problem, and the pin to the coating layer made of the second resin material can be suppressed. The occurrence of holes can also be significantly reduced, and the appearance characteristics can be improved.

[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 a water-repellent coating is formed, and FIG. Fig. 7 is a side sectional view showing a state in which an impregnated layer is formed, and Fig. 8 is a side sectional view showing a state in which a capacitor element is immersed in a second resin material. , FIG. 9 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 a water-repellent coating, 7 is a coating layer (first resin material), 8 is an impregnation layer (impregnation agent), and 9 is a coating layer (second resin material).

Claims (1)

[Claims] 1 a plurality of external lead members 3 extending in the same direction;
A step of immersing the component body 1 equipped with the component body 1 in a water-repellent material to form a water-repellent coating 6 on a desired portion of the external lead member; A process of immersing in a resin material to form a porous coating layer 7, a process of immersing this component body 1 in an epoxy resin impregnating agent to impregnate the coating layer 7 with an impregnating agent 8, and further having thixotropic properties. A method for packaging an electronic component, comprising the step of immersing the water-repellent coating portions of the external lead members 3 and 4 in a second resin material 9 to cover the main parts including the component body 1. .