JP2000299243A - Laminated chip type electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the oxidation of external electrodes and obtain satisfactory electrical conduction by forming main electrode layers electrically connected to internal electrodes of a sintered metal consisting essentially of copper or nickel and arranging the external electrodes whose outer surfaces are covered with plated layers made of a noble metal which is hard to oxidize. SOLUTION: A laminated chip capacitor is fabricated by forming a green sheet from a dielectric material containing barium titanate, and forming an internal electrode 10 of a base metal such as nickel. Using a capacitor chip element assembly 11, which is formed by sintering a plurality of internal electrodes 10 and ceramic sheets alternately laminated one upon another as a substrate, the assembly 11 is provided at both ends thereof with external electrodes 12 electrically connected to the electrodes 10. The electrodes 12 have main electrode layers 12a formed of a sintered metal which is obtained by coating conductive paste, which consists mainly of copper or nickel, to both ends of the assembly 11 and sintering the conductive paste. The layers 12a are electrically connected to the electrodes 10. The outer surface of each electrode 12 is covered with an electroplated layer 12c made of a noble metal such as silver or gold which is hard to be oxidized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a multilayer chip type electronic component, and more particularly to an improvement of an external electrode suitable for electrically conductively joining a land portion of a circuit pattern with a conductive resin material. It is.

[0002]

2. Description of the Related Art As shown in FIG. 2, a multilayer chip type electronic component, for example, a multilayer chip capacitor, is formed by alternately laminating a plurality of internal electrodes 1 made of nickel or the like with a ceramic sheet and firing the resultant. The chip body 2 is formed, and external electrodes 3 electrically connected to the internal electrodes 1 are provided at both ends of the capacitor chip body 2.

Conventionally, the external electrode 3 of the multilayer chip capacitor is made of a sintered metal mainly composed of copper (Cu) or nickel (Ni) and is a main electrode layer 3a electrically connected to the internal electrode 1.
Is formed, the main electrode layer 3a is covered with a nickel (Ni) plating layer 3b for preventing solder erosion of the main electrode layer 3a, and further, the outer surface of the main electrode layer 3a is formed of tin (Sn) or an alloy thereof having good solderability. It is formed by covering with a plating layer 3c of Sn-Pb).

The multilayer chip capacitor has external electrodes 3
Is mounted on the board surface of the circuit board 4 by bonding and fixing it to the land portion 5 of the circuit pattern provided on the board surface of the circuit board 4 with solder 6.
There is a tendency to use a conductive resin paste containing silver (Ag) as a main component that does not contain (Pb).

If the conductive resin paste is used for bonding and fixing, the external electrode may be cured by a heat treatment so that the external electrodes are electrically and securely fixed to the lands of the circuit pattern. However, the outermost layer of the external electrode is tin (Sn) or its alloy.
In the case of a plating layer of (Sn-Pb), there is a possibility that electrical connection failure may occur due to oxidation of a bonding surface made of a conductive resin paste with heat treatment.

This tin (Sn) or its alloy (Sn-Pb)
The surface of the outermost layer formed by the plating layer tends to deteriorate with the passage of time even under a normal environment. In particular, the influence of humidity is large and conduction failure due to surface oxidation of the external electrode is likely to occur.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention prevents the heat treatment required for bonding and fixing with a conductive resin space and the aging of external electrodes due to environmental conditions and the oxidation of external electrodes due to the influence of humidity. It is a main object of the present invention to provide a multilayer chip electronic component capable of obtaining good electrical conduction with a land portion of a circuit pattern.

[0008] The present invention also provides a laminate in which the cost can be reduced from the material for forming the internal electrodes, good electrical continuity with the internal electrodes can be obtained, and good electrical continuity can be obtained with the land portions of the circuit pattern. Another object is to provide a chip-type electronic component.

[0009]

According to a first aspect of the present invention, there is provided a multilayer chip type electronic component, wherein a main electrode layer electrically connected to an internal electrode is formed of a sintered metal containing copper or nickel as a main component. In addition, an external electrode whose outer surface is covered with a noble metal plating layer that is hardly oxidized is provided.

According to a second aspect of the present invention, there is provided a laminated chip type electronic component, wherein a main electrode layer electrically connected to an internal electrode is formed of a sintered metal containing copper or nickel as a main component, and the main electrode is formed. It is constituted by providing an external electrode whose surface is covered with a plating layer of a noble metal which is hardly oxidized.

According to a third aspect of the present invention, there is provided a multilayer chip-type electronic component having an external electrode whose outer surface is covered with a plating layer of a noble metal which is hardly oxidized, such as silver, gold, palladium, platinum or an alloy thereof. It is constituted by.

The multilayer chip electronic component according to a fourth aspect of the present invention is configured by providing a base metal internal electrode.

[0013]

FIG. 1 shows an embodiment in which a multilayer chip capacitor is formed as a multilayer chip electronic component. In this multilayer chip capacitor, a ceramic green sheet is formed from a dielectric material containing barium titanate, and internal electrodes 10 are formed by printing on a base metal such as nickel, and a plurality of the internal electrodes 10 are alternately laminated with the ceramic sheet. Capacitor body 1 formed by firing
1 is used as a base, and external electrodes 12 electrically connected to the internal electrodes 10 are provided at both ends.

The external electrodes 12 are formed by applying a conductive paste containing copper (Cu) or nickel (Ni) as a main component to both ends of the capacitor body 11 and sintering the conductive paste to the internal electrodes 10 with a sintered metal. Main electrode layer 1 electrically conducting
2a, the main electrode layer 12a is covered with a nickel electroplating layer 12b for preventing solder erosion of the main electrode layer 12a, and furthermore, silver (Ag), gold (Au), palladium ( It is formed by covering with an electroplating layer 12c of noble metal, which is Pd), platinum (Pt) or an alloy thereof.

For the external electrodes 12, the nickel electroplating layer 12b is omitted, and a conductive paste containing copper (Cu) or nickel (Ni) as a main component is applied to both ends of the capacitor body 11, and this is baked. A main electrode layer 12a electrically connected to the internal electrode 10 is formed by the treated sintered metal, and its outer surface is hardly oxidized, such as silver (Ag), gold (Au),
It can also be formed by covering with a precious metal electroplating layer 12c which is palladium (Pd), platinum (Pt) or an alloy thereof.

In the multilayer chip capacitor configured as described above, since the internal electrodes 10 are formed of a base metal such as nickel, the cost can be reduced. Further, even if the internal electrode 10 is formed of a base metal, the main electrode layer 12a electrically connected to the internal electrode 10 is formed by a sintered metal containing copper (Cu) or nickel (Ni) as a main component. Twelve main electrode layers 12a and the internal electrodes 10 can have good electrical continuity.

The external electrode 12 is made of silver whose outer surface is hardly oxidized.
(Ag), gold (Au), palladium (Pd), platinum (Pt) or a precious metal electroplating layer 12c of these alloys. Even when mounted on the circuit board 15 by bonding and fixing to the land portion 14, the heat treatment required for bonding and fixing with the conductive resin paste and the deterioration of the external electrode due to the aging due to environmental conditions and the influence of humidity can be prevented, and the circuit pattern can be prevented. And good electrical continuity with the land portion 14 can be obtained.

In order to confirm its effectiveness, a capacitor chip having an internal electrode made of nickel was used as a base, and a conductive paste containing copper or nickel as a main component was applied and baked as shown in Table 1 below. Forming a main electrode layer,
One provided with a second plating layer made of nickel (Example 1
To 4) and those without the second plating layer (Examples 5 to 5).
8), a multilayer chip ceramic capacitor whose outer surface was covered with any one of silver, gold, palladium and platinum plating layers was produced.

In order to compare the characteristics with those of the respective embodiments, a main electrode layer was formed by baking a conductive paste containing copper as a main component with a capacitor chip body having an internal electrode formed of nickel as a base. A multilayer chip ceramic capacitor (conventional example) in which the electrode layer was covered with a nickel plating layer and the outer surface was further covered with a tin plating layer to provide external electrodes was produced. In addition, a multilayer chip ceramic capacitor (comparative example) provided with external electrodes made only of copper was also manufactured. Each of these multilayer chip ceramic capacitors is 2.0 ×
It was formed in a rectangular shape having a size of 1.2 × 0.6 mm.

[0020]

[Table 1]

The multilayer chip capacitor was connected to each of samples 1 to 1
The value was set to 0, and each of the alumina substrates was used as a circuit board, and five lands were adhered to the lands of the circuit pattern with a conductive resin, and the change in each conduction resistance was measured under the following test conditions. The resistance value of each conductive resistance was measured at the external electrode and the junction of the conductive resin by a measuring circuit connected at the points in FIG.

The conduction resistance at the first moisture resistance is 85 ° C., 8
5% RH: measured at 100 hours. The conduction resistance in the second PCT was measured at 121 ° C. and 95% RH2 Pascal: 100 hours. The conduction resistance at the third thermal shock is −55 ° C.
１２５125 ° C. (no normal temperature, 30 minutes / cycle each): 100
Measured in cycles. The results were as shown in Table 2 below. In the table, K indicates x1000.

[0023]

[Table 2]

As can be seen from Table 2, Sample Nos. 9 and 1
In the case of No. 0, the conduction resistance was greatly increased in any of the humidity resistance test, the PCT, and the thermal shock test, and the resistance value was increased 30 to 30,000 times as compared with Sample Nos. 1 to 8. Since the increase in the conduction resistance cannot secure the original circuit characteristics, the quality of the electronic circuit becomes poor. On the other hand, the samples Nos. 1 to 8 showed almost no change in conduction resistance in any of the tests.

In the above-described embodiment, the outer electrode is formed by covering the outer surface with a plating layer of any one of silver, gold, palladium and platinum. However, the outer surface is formed of an alloy of silver, gold, palladium and platinum. The same electrical characteristics can be obtained even with an external electrode covered with a plating layer formed by the above method. Even if the internal electrode is formed of a base metal such as nickel, as in the conventional example, if the external electrode is formed by covering the outer surface with a plating layer of silver, gold, palladium, platinum or an alloy thereof, the conductive property can be improved. Good electrical continuity or bonding by the adhesive resin is obtained.

The above-described configuration of the external electrodes can provide an effective effect not only as a multilayer chip capacitor but also as an external electrode of a multilayer chip inductor, an LC composite chip electronic component, a resonator, and the like.

[0027]

As described above, according to any one of the laminated chip electronic components according to the first to third aspects of the present invention, by providing the external electrode whose outer surface is covered with a noble metal plating layer which is hardly oxidized. The heat treatment required for bonding and fixing with a conductive resin space and the aging of the external electrodes due to environmental conditions and the effect of humidity can be prevented, and good electrical continuity with the land of the circuit pattern can be obtained. Can be prevented from being deteriorated.

According to the multilayer chip type electronic component of the present invention, the cost is reduced by forming the internal electrode from a base metal material, and the internal electrode is formed of a sintered metal mainly composed of copper or nickel. By forming a main electrode layer electrically conducting with the external electrode and providing an external electrode whose outer surface is covered with a plating layer of a noble metal having good solderability, good electrical conduction with the internal electrode is obtained, and Also, good electrical continuity can be obtained with the land portions of the circuit pattern.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a multilayer chip electronic component according to the present invention and measurement points of conduction resistance.

FIG. 2 is an explanatory diagram illustrating a configuration of a multilayer chip electronic component according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Internal electrode 11 Stacked chip body 12 External electrode 12a Main electrode layer 12b Nickel plating layer 12c Noble metal plating layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuji Maruno 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation F-term (reference) 4K044 AA13 AB10 BA06 BA08 BB02 BC02 BC14 CA15 CA18 5E001 AB03 AC09 AE02 AE03 AF00 AF06 AH01 AH07 AH08 AJ03

Claims (4)

[Claims] 1. A laminated chip in which a plurality of internal electrodes are alternately laminated with ceramic sheets and fired by laminating the laminated chip element as a base, and external electrodes electrically connected to the internal electrodes are provided at both ends of the tic element. In a type electronic component, a main electrode layer electrically connected to an internal electrode is formed of a sintered metal containing copper or nickel as a main component, and an external electrode whose outer surface is covered with a plating layer of a noble metal that is hardly oxidized is provided. A multilayer chip-type electronic component characterized in that: 2. An external electrode in which a main electrode layer electrically connected to an internal electrode is formed of a sintered metal containing copper or nickel as a main component, and a surface of the main electrode layer is covered with a noble metal plating layer which is hardly oxidized. The multilayer chip-type electronic component according to claim 1, further comprising an electrode. 3. An external electrode whose outer surface is covered with a plating layer of a noble metal which is hardly oxidized, such as silver, gold, palladium, platinum or an alloy thereof.
Or the multilayer chip electronic component according to 2. 4. The multilayer chip-type electronic component according to claim 1, further comprising a base metal internal electrode.