JPS6112668Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the improvement of electronic components, mainly solid electrolytic capacitors.

Generally, this type of solid electrolytic capacitor is
As shown in the figure, a metal wire having a valve action is implanted in advance as an anode lead B into a capacitor element A, which is made by press-molding and sintering a metal powder having a valve action, such as tantalum, niobium, or aluminum, into a cylindrical shape. A first external lead member C formed in an L shape is welded to the protruding portion of this anode lead B, and a second external lead member D formed in a straight shape is welded to the circumferential surface of the capacitor element A. A solder member F is used to connect to the formed electrode lead layer E, and then the main portion including the capacitor element 1 is covered with a resin material G.

By the way, this capacitor is mounted on a printed circuit board H, for example, as shown in FIG. 265℃
It is soldered to the printed conductor by immersing it in a molten solder tank K for about 10 seconds at a controlled temperature.

However, the first and second external lead members C and D are usually constructed by coating iron or iron-based core wires with copper, and the amount of copper used is as much as 30% by weight. Therefore, when immersed in the molten solder tank K, the first and second external lead members C,
D is rapidly heated by heat conduction from the molten solder tank K, and as a result, the solder layer plated on its surface melts and begins to flow down.
A slight gap is formed at the welding boundary between the external lead members C, D and the resin material G.

Moreover, the capacitor element A is heated to a high temperature in a short time by the heat conducted from the molten solder bath K through the first and second external lead members C and D. As a result, the solder member F on the circumferential surface of the capacitor element A becomes molten.
In order to flow out through the gap formed at the boundary between the second external lead member D and the resin material G, the second
There is a drawback that the external lead member D is electrically opened from the electrode lead layer E and cannot function as a capacitor.

Therefore, the present applicant has previously proposed a solid electrolytic capacitor in which the outer periphery of the solder member F is coated with a conductive member containing conductive powder or resin having a higher melting point than the solder member F. According to this proposal, when the capacitor is mounted on the printed board H, even if the solder member F becomes molten and flows out from the gap at the boundary between the second external lead member D and the resin material G, , an electrical connection relationship between the second external lead member D and the electrode extension layer E can be ensured. In particular, if silver powder is used as the conductive powder in the conductive member, it is possible not only to simply ensure the above-mentioned electrical connection relationship, but also to improve dielectric loss characteristics.

However, the coating of the solder member F with the conductive material causes the capacitor element A to be coated with the conductive material in the form of a suspension.
Depending on the viscosity of the viscosity, the conductive material may flow down from the capacitor element A after it is pulled up from the conductive member, resulting in a significant amount of coverage. May decrease. When mounting such a capacitor on a printed board H, the solder member F
There is a problem in that due to the outflow, it becomes difficult to ensure the electrical connection between the second external lead member D and the electrode extension layer E, and its reliability also deteriorates.

In consideration of these points, the present invention provides an electronic component which can significantly improve the coverage of solder members by conductive members with a simple configuration while ensuring an electrical connection relationship with the electrode extraction layer of the external lead member. An example of application to a solid electrolytic capacitor is described below.

In FIG. 3, 1 is a capacitor element (component body) made of a metal member having a valve action, and is formed by, for example, press-molding metal powder having a valve action into a cylindrical shape and sintering it. There is. 2
is an anode lead made of a metal wire having a valve action and led out from the capacitor element 1. For example, the anode lead is planted at the center of the metal powder prior to pressure molding. Reference numeral 3 denotes an electrode lead layer formed on the circumferential surface of the capacitor element 1 via an oxide layer, a semiconductor layer, and a graphite layer, and is made of a conductive material containing, for example, silver powder and resin. 4 is a first part formed in an L shape, for example.
The bent portion 4a of the external lead member is welded to cross the protruding portion 2a of the anode lead 2. Incidentally, a solder layer 5 is formed on the surface of the first external lead member 4 by means such as plating in order to improve solderability to a printed circuit board. Reference numeral 6 denotes a second external lead member formed in, for example, a straight shape, and one end portion 6a of the second external lead member 6 is connected to the electrode lead layer 3 using a solder member 7. Note that this second external lead member 6
A solder layer 8 is formed on the surface for the same purpose as the first external lead member 4. Reference numeral 9 denotes a coating layer of a conductive material formed around the outer periphery of the solder member 7, and is formed of a conductive material containing, for example, conductive powder, fiber material, or resin having a higher melting point than the solder member 7. Note that glass fiber is suitable as the fiber material, but asbestos, carbon fiber, etc. may also be used. Reference numeral 10 denotes an insulating member which is applied to cover the entire circumferential surface of the capacitor element 1, and can be covered by a dipping method, a powder coating method, etc. in addition to the molding method. Resin materials such as epoxy resin and phenol resin are suitable for this insulating member.

Next, a method of manufacturing this capacitor and a method of mounting it on a printed board will be explained. First, an electrode lead layer 3 is formed on the circumferential surface of a capacitor element 1 which is made by press-molding metal powder having a valve action into a cylindrical shape and sintering it through an oxide layer, a semiconductor layer, and a graphite layer.
form. Then, the first external lead member 4 is welded to the anode lead 2 led out from the capacitor element 1 so that the bent portion 4a intersects with the protruding portion 2a. Then, with one end 6a of the second external lead member 6 in contact with the electrode lead-out layer 3, the capacitor element 1 is placed in the molten solder bath so that the surface of the capacitor element on the lead-out side of the anode lead 2 is not immersed. By dipping and pulling up, the second external lead member 6 and the electrode lead layer 3 are electrically and mechanically connected by the solder member 7. Next, this capacitor element 1 is immersed in a liquid conductive member 9 containing conductive powder, fiber material, and resin having a higher melting point than the solder member 7 so that the outer periphery of the solder member 7 is covered, and then pulled up. Heat treatment. Thereafter, the entire circumferential surface of the capacitor element 1 is molded and covered with a resin material (insulating member) 10 to obtain a solid electrolytic capacitor.

Next, as shown in Figure 4, this capacitor is
The first and second external lead members 4 and 6 are attached to the printed board 11 so as to protrude from the back side, and each is immersed in a molten solder bath 12 whose temperature is controlled to be higher than the melting point of the solder member 7. .
Then, the first and second external lead members 4 and 6 are rapidly heated by heat conduction from the molten solder bath 12, and as a result, the solder layers 5 and 8 plated on their surfaces are melted. First, to start flowing down.
A slight gap is formed between the second external lead members 4 and 6 and the resin material 10. Since the capacitor element 1 and the solder member 7 are also heated by the conductive heat from the first and second external lead members 4 and 6, the solder member 7 eventually becomes molten and flows out from the above-mentioned gap. I come to do it. At this time, when using, for example, silver powder as the conductive powder in the conductive member of the coating layer 9, the outflow of the solder member 7 is suppressed, probably because the silver is alloyed with the solder member 7, and the solder member 7 is connected to the second external lead member 6. An electrical connection relationship with the electrode extraction layer 3 can be ensured. Then, by pulling up the printed board 11 from the molten solder bath 12, the soldering of the first and second external lead members 4 and 6 to the printed conductor is completed.

Since the coating layer 9 made of a conductive material is formed on the outer periphery of the solder member 7 that connects the second external lead member 6 to the electrode extraction layer 3 in this way, the first and second external lead members 4 , 6, the capacitor element 1 is heated and the solder member 7 becomes molten, and some of it flows out from the resin material 10. Although the cause is not necessarily clear, the second external The lead element 6 can maintain sufficient electrical connection to the electrode lead layer 3.

Moreover, since the fibrous material is mixed in the conductive material constituting the coating layer 9, it is possible to suppress the conductive material from flowing down when the capacitor element 1 is coated with the liquid conductive material by the dipping method. Therefore, by stabilizing the covering state of the solder member 7 with the conductive member, it is possible to ensure the electrical connectivity of the second external lead member 6 to the electrode lead layer 3, and to improve its reliability. You can also do that.

In this regard, the inventors used tantalum powder with a diameter of 1.0
An oxide layer, a semiconductor layer, and an electrode lead layer are formed on the circumferential surface of a capacitor element that is pressure-formed and sintered to a height of 1.05 mm and a tantalum wire (anode lead) extending from the capacitor element. ,
A first external lead member whose surface is soldered and has a wire diameter of 0.5 mm is welded. Then, one end of a second external lead member whose surface is soldered and whose wire diameter is 0.5 mm is connected to the electrode lead layer using a solder member. Next, glass fibers with a length of 0.8 mm were added to a suspension of silver powder, resin, and solvent.
A capacitor element is immersed in a conductive material containing 5.0% by weight, and the outer periphery of the solder material is coated. Thereafter, the entire circumferential surface of the capacitor element is coated with epoxy resin to obtain a tantalum solid electrolytic capacitor. This was attached to a printed board with a thickness of 1.2 mm, and the first and second external lead members were immersed in a molten solder bath controlled at 265°C for 10 seconds and pulled up. When we investigated the occurrence of poor connection to the extraction layer, we found that there were 0 occurrences out of 1000. However, out of 1000 items that use conductive materials that do not contain glass fibers,
A connection failure occurred in 5 of them. From this result, the effect of covering the second external lead member with the conductive member mixed with glass fiber was confirmed. Further, it is desirable that the fiber material be mixed in an amount of 0.5% by weight or more based on the base material.

Note that the present invention is not limited to the above-mentioned embodiments, and can be applied to electronic components such as capacitors other than solid electrolytic capacitors, resistors, and coils. In addition to silver powder, tin, copper, nickel, etc. can also be used as the conductive powder in the conductive member (coating layer). Furthermore, the length of the fiber material and the amount mixed can be changed as appropriate.

As described above, according to the present invention, with a simple configuration, it is possible to significantly improve the coverage of the solder member with the conductive member, and to maintain a good electrical connection relationship between the external lead member and the electrode lead layer. .

[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 method of soldering to a printed circuit board, and Fig. 3 is a side sectional view showing an embodiment of the present invention. FIG. 4 is a side sectional view for explaining the method of soldering to a printed board. In the figure, 1 is a component body (capacitor element), 3 is an electrode lead layer, 4 and 6 are external lead members, 7 is a solder member, 9 is a conductive member, and 10 is an insulating member.

Claims (1)

[Scope of utility model registration request] An external lead member is connected to the electrode lead layer of the component body with a solder member, and the main part including the component body is covered with an insulating member, and the outer periphery of the solder member is made of a conductive material with a higher melting point than the solder member. An electronic component coated with a conductive material containing powder, fiber material, or resin.