JPH037136B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a leadless aluminum electrolytic capacitor. Conventional configurations and their problems Conventional so-called leadless electronic components of this type, such as chip-type aluminum electrolytic capacitors, are the first
It was constructed as shown in Figures a and b. That is, an anode foil formed by roughening aluminum foil and forming a dielectric oxide film by anodizing the surface, and a cathode foil formed by roughening aluminum foil are wound through a separator and impregnated with a driving electrolyte. This capacitor element 1 is housed in a cylindrical metal case 2 with a bottom, and the open end is covered with a sealing material 3 having elasticity such as rubber.
The lead wire 4 drawn out from the aluminum electrolytic capacitor is electrically and mechanically connected to the comb-shaped terminal 5 by a method such as welding, and then the comb-shaped terminal 5 is sealed. A molded resin exterior 6 was applied to the entire body except for 5 to form a completed product. This type of chip-type aluminum electrolytic capacitor is
In order to provide solder heat resistance when mounting on a printed circuit board, a molded resin exterior 6 is applied as described above, but in general, the molded exterior is
Pressure is applied at a temperature of 100℃ to 150℃ for about 5 minutes at a pressure of 10Kg/ ^cm2 . Under such harsh conditions, the driving electrolyte of the electrolytic capacitor evaporates, causing a decrease in capacitance and a decrease in tanδ. However, since it is coated with molded resin, it is extremely expensive. Furthermore, since it is a horizontal type, when it is mounted on a printed circuit board, it occupies a large area of the printed circuit board, which is a factor that hinders miniaturization of various devices. In order to solve these problems, the present inventors have recently proposed a vertical chip aluminum electrolytic capacitor as shown in FIGS. 2 and 3. In other words, this vertical chip aluminum electrolytic capacitor consists of an anode foil and a cathode foil, each of which has been roughened by etching to increase its surface area, and which are wound together with a separator in between, and the lead is connected to the capacitor element 7, which is impregnated with a driving electrolyte. Pull out line 8,
The capacitor element 7 is then housed in a bottomed cylindrical case 9 made of metal such as aluminum, an elastic sealing body 10 is assembled into the opening of the case 9, and the case 9 is sealed by drawing and curling. , and on the end face of this elastic sealing body 10 side,
Two lead wires 8 drawn out from the elastic sealing body 10
An insulating plate 13 having a through hole 11 passing through the through hole 11 and having a recess 12 connected to the through hole 11 formed on the outer end surface is disposed, and the lead wire 8 is bent into the recess 12 of the insulating plate 13 and is flattened. Processed flat part 8a
It is constructed by storing. In addition, this type of vertical chip aluminum electrolytic capacitor has a flattened portion 8a formed by processing the lead wire 8, as shown in FIG.
As shown in b, it is composed of a high purity aluminum plate 14a and a CP wire 14b. Furthermore, this CP wire 14b has iron 15 as a core wire, copper layer 16, tin layer 1
It consists of 7. In this case, the copper layer 16 and the tin layer 17 of the flat part 8a
A copper-tin alloy layer grows on the contact surface with the iron layer 15,
It consists of a copper layer 16, a copper-tin alloy layer, and a tin layer 17. And the Pickkers hardness of copper is 80
degree to 100 degrees, the Vickers hardness of the copper-tin alloy layer is
Since there is a large difference between 300 degrees and 500 degrees, the copper-tin alloy layer of the copper layer 16 is easily cracked by external mechanical stress. There were many defects such as peeling. Purpose of the Invention The purpose of the present invention is to eliminate such conventional drawbacks, and to provide an inexpensive vertical type leadless aluminum electrolytic capacitor that does not cause characteristic deterioration and can be firmly soldered to a printed circuit board. It is something to do. Structure of the Invention In order to achieve the above object, the present invention involves winding an anode foil and a cathode foil with a separator in between, and enclosing a capacitor element in which the anode foil and the cathode foil are impregnated with a driving electrolyte in a bottomed cylindrical case. , and an insulating plate having a recess connected to a through hole through which the lead wire is passed is placed on the end face of the opening from which the lead wire led out from the capacitor element of the case is drawn, and the lead wire is bent in the recess. At the same time, the lead wire is coated with an iron core wire, a copper layer, a tin/lead alloy layer,
It is constructed by sequentially laminating tin layers. By using lead wires constructed in this way, there is no direct contact between the copper layer and the tin layer, which eliminates the possibility of copper/tin alloy growth, which ensures that even after a long period of time, Since there is no physical change in the lead wire, that is, no copper layer or copper/tin alloy layer is formed, it is possible to eliminate the peeling phenomenon of the lead wire due to external mechanical stress. It is something. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below. The configuration of the aluminum electrolytic capacitor in one embodiment of the present invention is exactly the same as that shown in FIGS. 2 and 3, and the explanation thereof will be omitted here. The feature of the present invention lies in the lead wire 8, which, as shown in FIG. Tin/lead alloy layer 20 on the outer periphery
is similarly formed, and further this tin/lead alloy layer 20
A tin layer 21 is provided on the outer periphery of the aluminum plate, which is connected to a high-purity aluminum plate by welding or the like. This high-purity aluminum plate is then connected to the anode foil or cathode foil of the capacitor element 7 by a screw or the like. Next, a comparative example of the present invention and a conventional chip aluminum electrolytic capacitor will be shown. Both the conventional product and the product of the present invention are chip aluminum electrolytic capacitors with the configuration shown in Figure 3 (rated value 16V, 10μF).
We prepared 1000 pieces of each. The conventional lead wire is a flattened CP wire consisting of an iron core wire with copper and tin layers.
The lead wire of the product of the present invention is made of iron and a core wire, on which a copper layer, a tin/lead alloy metal, and a tin layer are successively laminated, and then flattened. Mount these products on a printed circuit board and heat at 40℃, 85-90%
A RH and 250 hour humidity test was conducted. After this test, the soldering strength was examined and the results are shown in the table below.

[Table] Test A shows the number of solder pieces that have peeled off visually in Test A, and furthermore, in Test B, the number of pieces that have peeled off when the remaining product from Test A is pressed by hand. This is what is shown. As is clear from the results in the table, a total of 13 soldering defects occurred in the conventional product, whereas no soldering defects occurred in the product of the present invention. Effects of the Invention As described above, in the aluminum electrolytic capacitor of the present invention, an anode foil and a cathode foil are wound with a separator in between, and a capacitor element in which the anode foil and the cathode foil are impregnated with a driving electrolyte is enclosed in a bottomed cylindrical case. An insulating plate having a recess connected to a through hole through which the lead wire is passed is arranged on the end face of the opening from which the lead wire led out from the capacitor element of the case is drawn, and the lead wire is folded into the recess. In addition to being bent and stored, the lead wire is constructed by sequentially laminating a copper layer, a tin/lead alloy layer, and a tin layer on an iron core wire, and the lead wire constructed in this way is used. As a result, there is no direct contact between the copper and tin layers, resulting in no copper/tin alloy growth, resulting in no physical changes to the leads, even after severe moisture testing. Therefore, the reliability of soldering can be significantly improved. In addition, a vertical, inexpensive chip-shaped structure can be obtained.

[Brief explanation of drawings]

Figures 1a and b are cross-sectional views and side views of a conventional chip-type aluminum electrolytic capacitor, Figure 2 is a perspective view of a vertical chip aluminum electrolytic capacitor proposed by the present inventors, and Figure 3 is an illustration of the same capacitor. 4a and 4b are perspective views and sectional views showing a conventional lead wire and its structure; FIG. 5 is a sectional view showing the structure of an aluminum electrolytic capacitor lead wire according to an embodiment of the present invention; FIG. It is. 7... Capacitor element, 8... Lead wire, 8a
... flat part, 9 ... case, 10 ... elastic sealing body, 11 ... through hole, 12 ... recess, 13 ... insulating plate, 18 ... iron core wire, 19 ... copper layer, 20 ...
...Tin/lead alloy layer, 21...Tin layer.

Claims (1)

[Claims] 1. A capacitor element in which an anode foil and a cathode foil are wound through a separator and impregnated with a driving electrolyte is enclosed in a bottomed cylindrical case, and a lead wire led out from the capacitor element in the case. An insulating plate having a recess connected to a through hole through which the lead wire is passed is placed on the end face of the opening from which the lead wire is drawn out, and the lead wire is bent and stored in the recess. An aluminum electrolytic capacitor constructed by sequentially laminating a copper layer, a tin/lead alloy layer, and a tin layer on a core wire.