JP3436127B2 - Terminal electrodes for electronic components and electronic components - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in electronic parts such as multilayer capacitors, and is used for applying conductive paste.
TECHNICAL FIELD The present invention relates to a terminal electrode formed by baking and an electronic component using the terminal electrode, and more specifically, to an electronic component terminal electrode having a structure in which a plurality of electrode layers are laminated and an electronic component using the terminal electrode. .

[0002]

2. Description of the Related Art Conventionally, an external connection terminal electrode of an electronic component has usually been formed by applying and baking a conductive paste. This kind of conductive paste is made of Ag or Ag-Pd.
Such as metal powder, glass frit, organic binder resin, and solvent. An example of a conventional electronic component terminal electrode formed by applying and baking a conductive paste will be described with reference to FIGS. 2 and 3.

FIG. 2 is a sectional view showing an example of a conventional multilayer capacitor having terminal electrodes formed thereon. The multilayer capacitor 11 is configured by using a ceramic sintered body 12 made of dielectric ceramics. In the ceramic sintered body 12, the internal electrodes 13a to 13f are arranged so as to overlap with each other with a ceramic layer interposed therebetween. Internal electrodes 13a, 1
3c and 13e have internal electrodes 13b and 13 on the end face 12a.
d and 13f are the other end faces 1 facing the end face 12a.
It has been pulled out to 2b.

Terminal electrodes 14 and 15 are formed so as to cover the end faces 12a and 12b, respectively. Terminal electrode 14,
Reference numeral 15 denotes electrode layers 14a and 15a formed by applying and baking a conductive paste containing a metal powder such as Ag.
Ni plating layers 14b and 15b formed on the electrode layers 14a and 15a and for preventing solder erosion of the electrode layers 14a and 15a, and formed on the outermost side and for improving solderability Sn plating layers 14c and 15c
Have and.

As described above, the electrode layers 14a and 15a
Is formed by applying and baking a glass frit-containing conductive paste. However, when the glass frit used has a low solubility in the plating solution, the plating layer 14
When forming b, 14c, 15b, and 15c, there was a problem that the plating solution penetrated into the ceramic sintered body 12 from the portion where the internal electrode was pulled out, resulting in deterioration of electrical characteristics and mechanical characteristics. . On the contrary, when a glass frit having a high resistance to the plating solution is used, the electrode layers 14a and 15
Since the Ni plating layers 14b and 15b cannot be surely adhered to the outer surface of the a, the Ni plating layers 14b and 15b
There was a problem that the adhesion state of 15b became unstable.

Therefore, a terminal electrode having a two-layer structure of an electrode layer formed by applying and baking a conductive paste has been proposed, such as the multilayer capacitor shown in FIG. In the multilayer capacitor 21 shown in FIG. 3, the terminal electrode 2
Reference numerals 4 and 25 are formed so as to cover the end faces 12a and 12b, respectively, and are formed on the electrode layers 24a and 25a containing a relatively large amount of glass and on the electrode layers 24a and 25a, respectively. Electrode layers 24b, 25b containing a small amount of glass, and electrode layers 24a, 24b, 25a, 25 formed on the electrode layers 24b, 25b.
Ni plating layer 24c for preventing solder erosion of b,
25c, and Sn plating layers 24d and 25d formed on the outermost layer for improving solderability.

Here, a relatively large amount of glass is contained in the electrode layers 24a, 25a which are in direct contact with the end faces 12a, 12b, thereby enhancing the sealing property of the electrode layers 24a, 25a, and the Ni plating layer 24c, 25c and Sn
The plating solution is prevented from entering the ceramic sintered body 12 when the plating layers 24d and 25d are formed.

[0008]

However, in the above-mentioned terminal electrodes 24 and 25, the end surface 1 of the ceramic sintered body 12 is
2a, 12b and the glass contained in the electrode layers 24a, 25a excessively react, that is, the glass component diffuses into the ceramic sintered body 12, and the ceramic sintered body 12 becomes brittle or cracks occur. However, there is a problem that the mechanical properties of the ceramic sintered body 12 are deteriorated. In addition, the bonding strength of the terminal electrodes 24 and 25 to the ceramic sintered body 12 was reduced, and the terminal electrodes 24 and 25 were sometimes peeled off.

The object of the present invention is to prevent the deterioration of the electrical and mechanical characteristics of the electronic component body due to the penetration of the plating solution when the plating layer is formed on the outer surface, and to obtain a strong plating property. An object is to provide a terminal electrode for an electronic component and an electronic component using the terminal electrode for an electronic component.

[0010]

According to a first aspect of the present invention, there is provided a terminal electrode for an electronic component, which is formed by baking a conductive paste containing glass frit. A third electrode layer is provided, and the glass content rate of the second electrode layer is higher than the glass content rates of the first and third electrode layers.

According to a second aspect of the invention, the glass content of the second electrode layer is in the range of 15 to 90% by volume. In the invention according to claim 3, the film thickness of the second electrode layer is in the range of 2 to 150 μm.

According to a fourth aspect of the present invention, there is provided an electronic component,
The electronic component terminal electrode according to any one of claims 1 to 3 is formed on an outer surface of an electronic component base body mainly made of ceramics.

According to a fifth aspect of the invention, the electronic component element body further includes an internal electrode electrically connected to the terminal electrode.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be made clear by giving non-limiting examples of the present invention.

FIG. 1 is a sectional view showing a multilayer capacitor having a terminal electrode formed thereon according to an embodiment of the present invention. The multilayer capacitor 1 has a ceramic sintered body 2 as an electronic component element body. The ceramic sintered body 2 has a rectangular parallelepiped shape and is made of an appropriate dielectric ceramic.

Inside the ceramic sintered body 2, internal electrodes 3a are formed.
.About.3f are arranged so as to overlap each other in the thickness direction via the ceramic layer. The internal electrodes 3a, 3c, 3e are drawn to one end surface 2a of the ceramic sintered body 2, and the internal electrodes 3b, 3d, 3f are drawn to the other end surface 2b facing the end surface 2a. There is.

The internal electrodes 3a to 3f are made of Ag or Ag-P.
It is made of an appropriate metal material such as d, Ni, or Cu. Usually, when obtaining the ceramic sintered body 2,
First, a plurality of ceramic green sheets are laminated with the internal electrode material formed by applying and printing a conductive paste interposed therebetween. Next, the obtained laminated body is fired to obtain a ceramic sintered body 2.

Terminal electrodes 4, 5 are formed so as to cover the end surface 2a of the ceramic sintered body 2 and reach the upper surface 2c, the lower surface 2d and a pair of side surfaces (not shown).
In the multilayer capacitor of this example, the terminal electrodes 4 and 5 were formed by baking a glass frit-containing conductive paste on the outer surfaces of the first to third electrode layers 4a to 4c and 5a to 5c, and further Ni plating layers. 4d, 5d and Sn plating layers 4e, 5e are formed. That is, each terminal electrode 4 and 5 has a structure in which five layers are laminated.

The first electrode layers 4a and 5a have end faces 2a and 2a, respectively.
It is formed as the innermost layer so as to be in direct contact with b, and has a glass content lower than that of the second electrode layers 4b and 5b. Further, the glass content of the third electrode layers 4c and 5c is lower than that of the inner second electrode layers 4b and 5b. That is, the terminal electrodes 4, 5
In, the glass content of the second electrode layers 4b and 5b existing between the first and third electrode layers is relatively increased.

Therefore, the glass content of the first electrode layer is
Since it is lower than the glass content of the second electrode layer, it is difficult for the glass component to excessively diffuse into the ceramic sintered body 2 during baking. Therefore, the mechanical strength of the ceramic sintered body 2 is unlikely to decrease.

On the other hand, since the second electrode layers 4b and 5b have a high glass content, they function as barrier layers for preventing the plating solution from entering the inside. That is, when forming the Ni plating layers 4d and 5d and the Sn plating layers 4e and 5e,
Even when the wet plating method is used, the second electrode layer 4
Since the glass contents of b and 5b are high, the invasion of the plating solution into the interior is reliably suppressed by the widely distributed glass components.

Furthermore, since the glass content of the third electrode layers 4c and 5c is lower than that of the second electrode layers, the Ni plating layer is formed on the outer surfaces of the third electrode layers 4c and 5c. 4d and 5d can be reliably attached.

Therefore, the first to third electrode layers 4a to 4c,
By using the structure in which 5a to 5c are laminated as described above, it is possible to reliably prevent the deterioration of the electrical and mechanical characteristics of the ceramic sintered body due to the penetration of the plating solution when the plating layer is formed on the outside. In addition to the above, the plating layer can be firmly adhered to the outer surface thereof.

The glass content of the second electrode layers 4b and 5b is preferably in the range of 15% by volume to 90% by volume after baking, as will be apparent from the experimental examples described later. If it is less than 15% by volume, the second electrode layer may not function sufficiently as a barrier layer for suppressing the invasion of the plating solution, and if it exceeds 90% by volume, the conductivity may decrease and it may function as an electrode. There are times when you don't.

The film thickness of the second electrode layers 4b and 5b is preferably in the range of 2 μm or more and 150 μm or less. If the thickness is less than 2 μm, the function as a barrier layer against the penetration of the plating solution may deteriorate, and the mechanical properties and insulation resistance of the ceramic sintered body may decrease.
If it exceeds 0 μm, the resistance of the electrode may increase.

The first to third electrode layers 4a to 4c, 5
The layers a to 5c may be formed by baking each layer, or may be formed by stacking conductive pastes for forming the first to third electrode layers and then baking them at once.

Further, the multilayer capacitor 1 shown in FIG.
The electronic component according to the present invention is merely an example of the electronic component according to the present invention, and the electronic component terminal electrode according to the present invention is formed on the outer surface of an electronic component base body mainly composed of ceramics. It can be generally applied to structures. Therefore, the present invention can be applied not only to the multilayer ceramic electronic component but also to a single plate type ceramic electronic component.
Further, the electronic component having the internal electrode is not limited to the multilayer capacitor, the multilayer varistor, the multilayer piezoelectric resonance component, and the like, and the electronic component having a single layer of the internal electrode, for example, a pair of internal electrodes arranged facing each other at the same height position. The present invention can be applied to a thermistor, a resistance element, etc.

Next, a concrete experimental example will be described. The ceramic sintered body 2 shown in FIG. 1 has BaTiO ₃ as a main component, has a size of 3.2 mm × 1.6 mm × 1.6 mm, and internally has an internal electrode made of 100 layers of Ag—Pd alloy. The formed ceramic sintered body 2 was prepared. An Ag conductive paste was applied so as to cover the end faces 2a, 2b of the ceramic sintered body 2, and the electrodes were formed by baking to obtain a multilayer capacitor 1.

As the conductive paste, 60 to 75% by weight of Ag powder, 1 to 10% by weight of Pb-Bi-Al-Si-B based glass (softening point 500 ° C.) and 2 to 5% by weight of organic binder resin are used. % Was used. The baking temperature was 600 ° C. However, as a result of sequentially forming the first to third electrode layers 4a to 4c and 5a to 5c according to the above method, the glass content and the film thickness in each of the electrode layers 4a to 4c and 5a to 5c are as follows. there were.

First electrode layers 4a, 5a ... Glass content is 8% by volume and film thickness is 15 μm. Second electrode layers 4b, 5b ... Glass content and film thickness are variously changed as shown in Table 1 below. Third electrode layers 4c, 5c ... Glass content is 2% by volume and film thickness is 15 μm.

In each of the multilayer capacitors of Comparative Example and Examples 1 to 6 in which the first to third electrode layers are formed as described above, further, outside the third electrode layers 4c and 5c,
Ni plating layers 4d and 5d are formed to have a thickness of 2 μm.
Further, Sn plating layers 4e and 5e were formed on the outside by a wet plating method so as to have a thickness of 3 μm.

For each of the multilayer capacitors of Comparative Examples and Examples 1 to 6 obtained as described above, the Ni plating layer 4
Insulation resistance is measured before forming d and 5d, and S
After forming the n-plated layers 4e and 5e, the insulation resistance was measured to evaluate the deterioration of the insulation resistance. In this case, the case where the rate of decrease in insulation resistance was less than 50% was determined as "no deterioration", and the case where the insulation resistance decreased by 50% or more was determined as "deterioration". The results are shown in Table 1 below.

[0033]

[Table 1]

As is apparent from Table 1, in the multilayer capacitor of the comparative example, the glass content of the second electrode layer was equal to the glass content of the first electrode layer and was 8% by volume.
The second electrode layer did not function as a barrier layer, and therefore the number of insulation resistance deterioration after plating was 58 per 100, which was very large.

On the other hand, in the laminated capacitors of Examples 1 to 6, the insulation resistance was deteriorated after plating, probably because the glass content of the second electrode layer was all higher than that of the first electrode layer. It can be seen that the number of multilayer capacitors used was 100 or less, which was significantly less than 10.

In particular, the glass content of the second electrode layer is 15
In Examples 2 to 6 in which the volume% is not less than, the ratio of the multilayer capacitor having deteriorated insulation resistance is further reduced, and the film thickness of the second electrode layer is not less than 2 μm.
In Nos. 5 and 6, there were no multilayer capacitors with deteriorated insulation resistance.

Therefore, the glass content of the second electrode layer is 1
It can be seen that by setting the film thickness to 5% by volume or more and the film thickness to 2 μm or more, it is possible to more effectively prevent the deterioration of the insulation resistance due to the penetration of the plating solution.

[0038]

According to the first aspect of the present invention, the terminal electrode for electronic parts has a structure in which first to third electrode layers formed by baking a conductive paste containing glass frit are laminated, and Since the glass content of the electrode layer of is higher than the glass content of the first and third electrode layers,
Even if the plating layer is formed on the outer side of the electrode layer, the second electrode layer functions as a barrier layer against the invasion of the plating solution, and deterioration of the characteristics of the electronic component due to the invasion of the plating solution, such as insulation resistance It is possible to reliably prevent deterioration and deterioration of mechanical properties. Therefore, it is possible to increase the yield rate of electronic components at the time of production and to provide electronic components with excellent reliability.

In the electronic component according to the fourth aspect of the present invention, since the terminal electrode for an electronic component according to the present invention is formed on the outer surface of the electronic component body mainly made of ceramics, the plating layer is formed on the outer surface. Even in the case of forming, the deterioration of the characteristics such as the decrease of the insulation resistance due to the penetration of the plating layer is hard to occur, and the reliability can be improved.

Further, in the invention according to claim 5, the electronic component element body is provided with the internal electrode electrically connected to the terminal electrode, but since the electronic component element body has the terminal electrode according to the present invention, the internal electrode is Penetration of the plating solution from the portion drawn out to the outer surface of the electronic component body is reliably suppressed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a multilayer capacitor having a terminal electrode according to an embodiment of the present invention.

FIG. 2 is a sectional view for explaining a terminal electrode of a conventional multilayer capacitor.

FIG. 3 is a sectional view for explaining another example of the terminal electrode of the conventional multilayer capacitor.

[Explanation of symbols]

1 ... Multilayer capacitor as electronic component 2 ... Ceramic sintered body as an electronic component body 3a to 3f ... internal electrodes 4, 5 ... Terminal electrodes 4a, 5a ... First electrode layer 4b, 5b ... Second electrode layer 4c, 4c ... Third electrode layer 4d, 5d ... Ni plating layer 4e, 5e ... Sn plated layer

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-273418 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01G 4/00-4/40

Claims (5)

(57) [Claims] 1. A terminal electrode for an electronic component, which is formed by baking a conductive paste containing glass frit, having first to third electrode layers sequentially formed on the surface of the electronic component body, and a second electrode. A terminal electrode for electronic parts, wherein the glass content of the layer is made higher than the glass content of the first and third electrode layers. 2. The glass content of the second electrode layer is 15
The terminal electrode for electronic parts according to claim 1, which is in a range of 90% by volume. 3. The film thickness of the second electrode layer is 2 to 150 μm.
The terminal electrode for electronic parts according to claim 1 or 2, which has a range of m. 4. An electronic component, wherein the electronic component terminal electrode according to any one of claims 1 to 3 is formed on an outer surface of an electronic component body mainly composed of ceramics. 5. The electronic component according to claim 4, wherein the electronic component body further includes an internal electrode electrically connected to the terminal electrode.