JPS5934125Y2 - electronic components - Google Patents

Description

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

In general, this type of solid electrolytic capacitor is made of a capacitor element A made by press-molding metal powder having a valve action into a cylindrical shape and sintering it, as shown in Fig. 1, and a metal wire having a valve action as an anode lead. A first external lead member C bent in an L shape is welded to the protruding portion of the anode lead B, and a second external lead member C is formed on the circumferential surface of the capacitor element A. Electrode extraction layer E
After that, the main parts including the condenser element A are covered with a resin material G.

By the way, this capacitor is mounted on a printed board H, for example, as shown in FIG. The printed conductors are soldered by being immersed in a molten solder bath K controlled at about 0.degree. C. for about 10 seconds.

However, usually the first. The second external lead members C and D are constructed by coating iron or a core wire mainly composed of iron with copper, and the amount of copper used is as much as 30% by weight. The second external lead members C and D are connected to the melting solder tank K.
When immersed in the molten solder bath K, the capacitor element A is immersed in the first molten solder bath K. The heat conducted through the second external lead members C and D heats it to a high temperature in a short time.

As a result, the capacitor element member F becomes molten and is eluted from the resin material G along the second outer lead member, so that the second outer lead member is electrically opened from the electrode extraction layer E. Sisters,
The drawback is that it cannot function as a capacitor.

In view of these points, this proposal suppresses heating of the component body due to heat conducted through the external lead member with a simple configuration, and can significantly reduce connection failures of the external lead member due to solder material flowing out. The present invention provides electronic components, and examples thereof will be described below.

In FIG. 3, reference numeral 1 denotes a component body, and the illustrated example is a condenser element formed by press-molding metal powder having a valve action into a cylindrical shape and sintering it.

Reference numeral 2 denotes an anode lead made of a metal wire having a valve action and led out from the capacitor element 1. In the illustrated example, the anode lead is planted at the center of the capacitor element 1 prior to or at the same time as pressure forming. It can also be derived by welding to the peripheral surface.

Reference numeral 3 denotes an electrode lead layer formed on the circumferential surface of the capacitor element 1 via an oxide layer and a semiconductor layer, and is constructed by, for example, polymerizing a silver paste layer on a Grapheye I layer.

Reference numeral 4 denotes a first external lead member constructed by coating iron or a core wire mainly composed of iron with a metal other than iron, and the illustrated example is constructed by coating a core wire made of iron with copper. There is.

The first external lead member 4 is formed, for example, in an L shape, and its bent portion 4A is welded to the anode lead 2 so as to intersect with the protruding portion 2a.

Further, a portion of the first external lead member 4 covered with an insulating member, which will be described later, is formed with a portion (uncovered portion 4b) in which the core wire is not covered.

Note that this uncoated portion 4b is formed by a chemical or mechanical method.

A second external lead member 5 is made of the same material as the first external lead member 4, and one end 5a of the second external lead member 5 is soldered to the electrode lead layer 3 with a layer 6 of a solder member.

A portion (uncoated portion 5b) in which the core wire is not covered is formed in a portion of the second external lead member 5 covered with an insulating member, which will be described later.

Reference numeral 7 denotes an insulating member such as a resin material that is applied to cover the main portion including the condenser element 1.

In this way, the first. Since uncoated portions 4b and 5b of core wires made of metal other than iron are formed in the portions of the second outer guide members 4 and 5 covered by the insulating member 7, for example, when mounting a capacitor on a printed board, 1st hit. Even if the second external lead members 4 and 5 are immersed in the molten solder bath for about 10 seconds, the condenser element 1 is not heated until the solder member 6 attached to the circumferential surface thereof becomes molten.

Therefore, the connection of the second external lead member 5 to the electrode lead layer 3 is poor due to the melting of the solder member 6 that solders the second external lead member 5 to the electrode lead layer 3 and the protrusion from the insulating member 7. can be significantly reduced.

In particular, the first. When the second external lead members 4 and 5 are constructed by covering a core wire made of iron with copper, heat conduction to the capacitor element 1 is improved by forming silver uncoated parts 4b and 5b. This can be effectively suppressed, and connection failures of the second external lead member 5 to the electrode liquid draining layer 3 can be further reduced.

In addition, the oxide layer as a dielectric layer in this capacitor tends to be thermally degraded. The immersion time in the molten solder layer is about 10 seconds because the uncoated parts 4b and 5b of the core wire made of metal other than iron are formed in the part covered by the insulating member 7 of the second external lead member 4.5. If it is below, the temperature rise of the capacitor element 1 can be suppressed to a low level, and an increase in leakage current due to thermal deterioration of the oxide layer can be prevented.

Next, specific examples will be described.

A tantalum wire (anode lead) of 0.3 φmm is planted in tantalum powder, pressure-molded into a cylindrical shape with a diameter of 3 mm and a height of 4 mm, and sintered to form a condenser element.

Then, an oxide layer, a semiconductor layer, and an electrode lead layer are sequentially formed on the circumferential surface of this capacitor element.

Next, the core wire made of iron is coated with copper on the tantalum wire protruding from the condenser element, and the surface of the copper is plated with solder, and the copper coating layer and the solder plating are removed in a portion of the tantalum wire with a length of 4 mm. The first external lead member having a diameter of 0.4 mm is welded.

Then, one end of a second external lead member having the same structure as the first external lead member is immersed in a molten solder tank while being in contact with the electrode lead layer, and then pulled up to be soldered.

After that, the entire circumferential surface of the capacitor element and the first. The portion of the second external lead member from which the copper coating has been removed is covered with epoxy resin.

This capacitor is attached to a 1.2 mm printed board.
, the second external lead member is attached so as to protrude from the back surface, and the first external lead member is attached so as to protrude from the back side. After immersing the second external lead member in a molten solder bath controlled at 266°C for 10 seconds and pulling it up,
When we investigated the connection failure (open failure) of the external lead member to the electrode extraction layer, the failure occurrence rate was 0%.

However, in the conventional product in which no copper uncoated portion was formed, about 20% of defects occurred.

Note that the present invention is not limited to the above embodiments in any way,
For example, capacitors other than solid electrolytic capacitors, resistors,
It can also be applied to electronic components such as coils.

In addition, the number of external lead members may be two, one or three or more, and the uncoated portion of the core wire made of a metal other than iron may be formed only on a desired external lead member.

In addition to copper, the covering metal of the core wire in the external lead member is copper.
nickel.

Lead, tin, silver, etc. can also be used.

Furthermore, as a method for covering the component body with an insulating member, any method such as a molding method, a dipping method, a thermal spraying method, etc. can be adopted.

As described above, according to the present invention, it is possible to effectively suppress heating of the component body due to heat conducted through the external lead member,
It is possible to significantly reduce connection failures of the external lead member to the electrodes of the component body due to outflow of the solder member.

[Brief explanation of the drawing]

Figure 1 is a front sectional view of a conventional example, Figure 2 is a front sectional view of the main part to explain the method of soldering a solid electrolytic capacitor to a printed board, and Figure 3 is a front sectional view of an embodiment of the present invention. FIG. In the figure, 1 is the component body, 4 and 5 are external lead members, 4b,
5b is an uncoated portion, 6 is a solder member, and 7 is an insulating member.

Claims (1)

[Scope of utility model registration request] In a product in which at least one of the external lead members led out from the component body is soldered to the component body and the main part including the component body is covered with an insulating material, one of the external lead members is soldered to the component body. An electronic component characterized in that the attached external lead member is constructed by coating iron or a core wire mainly composed of iron with a metal other than iron, and a portion where the core wire is not covered is formed in the portion covered by the insulating member.