JPS61234519A - Electronic component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to electronic components, and particularly relates to an external electrode structure in which soldering of an external lead member to an external electrode improves strength in a laminated ceramic or a 7-chip capacitor. be.

[Prior art]

Generally, this type of multilayer ceramic capacitor, for example,
As shown in the figure (Utility Model Application Publication No. 56-68089), external electrodes are attached to both ends of a capacitor element (A) in which a plurality of internal electrodes and ceramic layers are alternately and integrally arranged between protective layers. B, B are formed, external lead members C, C are soldered (D) to these external capacitors [B, B, and the entire circumferential surface of the capacitor element A is coated with powdered resin material E. has been done.

By the way, soldering of the capacitor element A of the external lead members C and C to the external electrodes B and B is performed, for example, as follows. That is, the capacitor element A is held between the external lead members C9C so that they are in contact with the external electrodes B and B.

In this state, it is immersed in a flux bath and pulled out. Thereafter, this clamping structure is immersed in a molten solder tank whose solder temperature is controlled at about 250° C. and pulled up, thereby completing the soldering of the external lead members C, C to the external electrodes B, B.

[Problem that the invention seeks to solve]

However, the external voltage 1iB of capacitor element A,
B is formed by sequentially contacting both ends of the capacitor (A) with a silver paste made of silver powder, frit glass, binder, and solvent, and then heat-treated. When the external lead member C is immersed in a molten solder bath when soldering the external lead member C to the electrode B, the silver constituting the external electrode B diffuses into the molten solder.

A so-called eating phenomenon occurs. This eating phenomenon tends to become more pronounced as the solder temperature of the molten solder tank becomes higher and as the time of immersion of the capacitor Niremen) A in the molten solder tank becomes longer.

Furthermore, although this kind of eating phenomenon occurs in all parts of the external electrode B, the formation thickness at the ends of the external electrode B is larger in the corner parts than in the center part. 5. Particularly in the thinner parts, the ceramic parts that make up the protective layer are exposed due to the eating phenomenon, and the proportion of silver in the surface layer of the external electrode B is small. It happens. For this reason, it goes without saying that soldering of the external lead member C at the central part of the external electrode B deteriorates, and it becomes impossible to solder the external lead member C to the external electrode B especially at the corner part. Or, even if it appears to be soldered, the soldering strength may be extremely low.

Therefore, when mounting such a capacitor on a printed board, if an external force is applied to the external lead members C in the direction of the arrow shown in FIG. In addition, the thickness of the coating with resin material E is thin.

Due to this, the external lead members C, C may be torn apart from the external electrodes B, B, resulting in an open failure.

Therefore, an object of the present invention is to provide an electronic component that has a simple configuration that can improve the strength of soldering an external lead member to an external electrode of the component body, and can reduce troubles when mounting it on a printed board. .

[Means to solve the problem]

Therefore, in order to achieve the above-mentioned object, the present invention includes soldering a plurality of external lead members to the external electrodes of a component body so that they lead out in the same direction, and also soldering the entire circumferential surface of the component body to a resin material. The external electrode is divided into a first electrode layer formed on the part body side and a second electrode layer polymerized on the first electrode layer, and the first electrode layer is made of metal. The second electrode layer is formed of a conductive member containing powder and frit glass, and the second electrode layer is formed of a conductive member containing metal powder but not frit glass.

[Effect]

According to this invention, the external electrodes of the component body are arranged in the first and second positions.
Moreover, since the second electrode layer to which the external lead member is soldered is made of a conductive material that contains metal powder and does not contain fried glass, it is difficult to melt. Even if metal powder, such as silver, is eaten away when soldering the external lead member to the external electrode by immersion in a solder bath, it is possible to prevent the surface layer of the frit glass from being exposed, and also prevent the parts from being exposed to the surface layer of the frit glass. exposure can also be prevented. Therefore, soldering properties of the external lead member to the external electrode can be improved, and the occurrence of open defects due to tearing can be suppressed.

〔Example〕

Next, an example of application of the present invention to a multilayer ceramic and a solid capacitor will be explained with reference to FIG.

In the figure, 1 is a capacitor element (component main body), for example, a plurality of internal electrodes, ceramic 1.
It is constructed by integrally disposing layers alternately, and external electrodes 2, 2 are formed at both ends thereof. This external electrode 2 is the first. Second electrode layer 2. ．． The first electrode layer 21 formed directly on the capacitor element 1 is made of a conductive material containing metal powder, such as silver powder, or glass, which is polymerized into the first electrode layer 2I. Second electrode layer 2! are each made of a conductive member that contains metal powder, such as silver powder, and does not contain glass.

These electrode layers are formed, for example, as follows. First, both ends of the capacitor element 1 are sequentially brought into contact with a silver paste (conductive member) consisting of silver powder, frit glass, binder, and solvent, and the proportion of the silver powder in the total amount is set to 70 to 75% by weight, and heat treatment is performed. As a result, the first electrode layer 2I is formed. In addition, the binder,
The solvent is removed. Next, a first electrode layer (21°21
The second electrode layer 2 is brought into contact with the second electrode layer 2 and heat treated.
．． is formed. In addition, 1st. Second electrode layer 2.2. can also be heat treated at the same time. An external lead member 8.3 is connected to the second electrode layer 2s, L by a solder member 4.4. The entire circumferential surface of the capacitor element 1 is coated with, for example, a powdered resin material 5.

Next, a specific example will be explained. First, apply silver powder and free glass to both ends of capacitor element 1. Consists of binder and solvent, and accounts for 75% by weight of the total silver powder
The first electrode layer 21 is formed by depositing a silver paste set to . Next, it consists of silver powder, binder, and solvent, and the proportion of the total silver powder is 80% by weight.
First, silver paste without frit glass set to
Electrode layer 2. form. In addition, 1st. The second electrode layers 28 and 2 are formed so as to slightly bulge out not only on the end surface of the capacitor element 1 but also on the upper and lower surfaces and side surfaces adjacent to the end surface. Next, the capacitor element 1 is held between the two external lead members 8.3, and the capacitor element 1 is flattened. Cover with camphor. Then, tin-silver-based high-temperature solder 4 with a melting point of 230°C was heated to 270°C.
The external lead member 3 is soldered to the second electrode layer 2 of the external electrode 2 by immersing it in a molten solder tank controlled at a temperature of 0.degree. C. for 6 seconds and pulling it up. Thereafter, the entire circumferential surface of the capacitor element 1 is covered with a powdered resin material 5 to produce a multilayer ceramic capacitor.

The external lead member 3.8 of this capacitor is pulled in the direction of the arrow shown in FIG.
．． We measured the force when it was peeled off, 1.6 V4
Met. In addition, in the conventional structure shown in Fig. 2, 0.8
It was the first time. In particular, as shown in FIG.
It was confirmed in another experiment that the strength of soldering can be further improved by wrapping it around the external electrode 3a that protrudes from the upper and lower surfaces.

The second electrode layer of this capacitor 2. When we investigated the state of the silver being eaten away, we found that although some silver was observed on the surface layer, no silver was observed at the corners that reached the surface of the capacitor element (protective layer). We also confirmed that it was completely absent from the surface of the layer. It is believed that soldering the external lead member 3 to the external electrode 2 contributes to improving the strength.

Incidentally, in the present invention, the electronic components include not only multilayer ceramic capacitors but also general ceramic capacitors and IC capacitors.

It can also be applied to resistance. Further, the metal powder of the conductive member forming the external electrode is not limited to silver powder, and the ratio thereof can be changed as appropriate within a range that does not impair soldering properties.

〔Effect of the invention〕

As described above, according to the present invention, the external electrode is divided into a first electrode layer and a second electrode layer, and the first electrode layer is made of metal powder.

Since the second electrode layer is made of a conductive member containing metal powder and not containing free glass, heat treatment time such as immersion time in a molten solder bath is shortened. Even if the length is a little longer, it is possible to improve the properties of metal powder, such as silver, due to the eating phenomenon, and the strength of soldering can also be improved.

Therefore, it is possible to suppress the occurrence of open defects due to tearing of the external lead member from the external electrode during mounting on a printed circuit board.

[Brief explanation of the drawing]

FIGS. 1 and 2 are side sectional views showing an embodiment of the present invention and a conventional example. In the figure, 1 is the component body (capacitor element), 2 is the external electrode, 2. is the first electrode layer, 2I is the second electrode layer, 3
4 is an external lead member, 4 is a solder member, and 5 is a resin material.

Claims (2)

[Claims] (1) Attach multiple external lead members to the external electrodes of the component body,
In a device in which the external electrode is soldered so as to be led out in the same direction and the entire peripheral surface of the component body is covered with a resin material, the external electrode is connected to a first electrode layer formed on the component body side.
a second electrode layer polymerized on the electrode layer;
An electronic component characterized in that the electrode layer is formed of a conductive material containing metal powder and frit glass, and the second electrode layer is formed of a conductive material containing metal powder but not frit glass. (2) The electronic component according to claim 1, wherein the metal powder is silver powder.