JP2002324720A - Laminated ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable laminated ceramic electronic component which is provided with a terminal electrode made of Cu as a conductive element and is superior in mounting substrate expansion resistance (expansion strength) and mounting substrate bending resistance (bending strength). SOLUTION: This laminated ceramic electronic component is provided with a ceramic laminated body that a plurality of ceramic layers are laminated, a plurality of internal electrodes which are formed among the ceramic layers in a manner that their end edges are exposed over any end surface of the ceramic laminated body, and a terminal electrode made of Cu as a conductive element that is electrically connected with the end edge of the internal electrode, and the Young's modulus of the terminal electrode is within 1.00×10<10> -4.00×10<10> N/m<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic electronic component, and more particularly to a mechanical strength capable of withstanding a stretching stress of a substrate due to a thermal shock at the time of mounting the substrate and a stress caused by a bending due to an external force applied to the substrate. A multilayer ceramic electronic component comprising:

[0002]

2. Description of the Related Art Conventionally, a multilayer ceramic electronic component, for example, a multilayer ceramic electronic component mainly includes a ceramic laminate, internal electrodes, and terminal electrodes. The ceramic laminate is, for example, formed by firing a raw laminate in which a plurality of raw ceramic layers containing a dielectric material are laminated. The internal electrode has a thickness of several hundred nm to several μm, is located between ceramic layers having a thickness of several hundred nm to 30 μm in a ceramic laminate, and a conductive paste is printed on a plurality of raw ceramic layers to form a raw ceramic. Co-fired with the layers,
Each edge of the internal electrode is formed so as to be exposed at any one of the end surfaces of the above-described ceramic laminate. The terminal electrode is formed by applying and baking a conductive paste to the end face of the ceramic laminate so as to be joined to one end of the internal electrode exposed on the end face of the ceramic laminate.

A conductive paste for forming a terminal electrode contains, for example, a conductive component, an organic vehicle, and a glass frit. Examples of the conductive component include metal powder. Ag or P
Base metals such as Ni and Cu are used in addition to noble metals such as d. In addition, the multilayer ceramic electronic component has been reduced in size and thickness, and accordingly, it has been required to reduce the metal powder contained in the conductive paste used for forming the internal electrodes.

[0004] Such a multilayer ceramic electronic component is mounted on a mounting board such as a circuit board or a printed wiring board, and a land formed on the board and a terminal electrode of the multilayer ceramic electronic component are electrically and soldered. Mechanically bonded and surface mounted.

[0005]

However, according to the prior art, when the ambient temperature changes abruptly or a thermal shock is applied, cracks are easily generated inside the multilayer ceramic electronic component due to the expansion and contraction stress of the circuit board. There was a tendency. In addition, since the multilayer ceramic electronic component is mounted on the circuit board, the stress due to the bending due to the external force applied to the circuit board is likely to be applied to the multilayer ceramic electronic component, and cracks tend to occur inside the multilayer ceramic electronic component as well. was there. In particular, a remarkable tendency was observed in the case of a multilayer ceramic electronic component using Ni as the conductive component of the internal electrode and Cu as the conductive component of the terminal electrode.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. The object of the present invention is to provide a mounting substrate with a terminal electrode containing Cu as a conductive component, a mounting substrate stretch resistance (stretching strength) and a mounting substrate bending resistance (bending resistance). It is an object of the present invention to provide a highly reliable multilayer ceramic electronic component having excellent strength.

[0007]

In order to achieve the above object, a multilayer ceramic electronic component according to the present invention comprises a ceramic laminate in which a plurality of ceramic layers are stacked and a ceramic laminate in which each edge is a ceramic laminate. A plurality of internal electrodes formed between the ceramic layers so as to be exposed at the end surfaces thereof, and C provided so as to be electrically connected to the edges of the internal electrodes.
a terminal electrode having u as a conductive component, and the terminal electrode has a Young's modulus of 1.00 × 10 ^{10 to} 4.00 × 10 ¹⁰ N / m.
It is characterized by being in the range of ² .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The Young's modulus of a terminal electrode can be calculated by obtaining a load unloading curve of a load using a microhardness tester. This method is a method in which a load is applied to a terminal electrode using an indenter having a long diameter of several μm, and it is possible to directly measure the terminal electrode of a multilayer ceramic electronic component without producing a bulk of the terminal electrode itself.

Factors that cause the Young's modulus of the terminal electrode to fluctuate include the particle size of the Cu material as the conductive component, the composition and particle size of the glass frit, the content ratio of each material in the conductive paste, and the baking temperature of the terminal electrode. And the atmosphere at the time of baking.

[0010] The larger the particle size of the Cu material, the lower the Cu content in the conductive paste, and the lower the temperature below the softening point of the glass frit, the more the baking is performed, the larger the voids in the terminal electrode, and the lower the Young's modulus. There is a tendency to decrease. Further, even when baking is performed at a temperature higher than the softening point of the glass frit, if the content ratio of the glass frit in the conductive paste is high, the glass penetrates into the inside of the ceramic laminate at the time of baking, and the terminal electrode A void is formed in the inside of the alloy, and similarly, the Young's modulus tends to decrease.

As described above, the Young's modulus of the terminal electrode fluctuates due to various factors. As a result of the stress analysis using the finite element method, the expansion stress and the bending stress generated when the multilayer ceramic electronic component is mounted on the mounting board. The force to withstand the stress, that is, the expansion and contraction strength and the bending strength of the terminal electrode of the multilayer ceramic electronic component tend to increase as the Young's modulus of the terminal electrode decreases, and as a result of the inventors' earnest research,
The Young's modulus of the terminal electrode of the multilayer ceramic electronic component is 1.
It was found that the elastic strength and the flexural strength were the strongest in the range of 00 × 10 ^{10 to} 4.00 × 10 ¹⁰ N / m ² .

The Young's modulus of the terminal electrode is 4.00 × 10 ¹⁰ N
/ M ² , it is difficult to obtain the effects of the present invention, ie, the improvement in the expansion and contraction strength and bending strength as described above. That is, cracks may occur due to concentration of stress inside the ceramic laminate.

On the other hand, the Young's modulus of the terminal electrode is 1.00 × 1
If it is less than 0 ¹⁰ N / m ² , it becomes difficult to use it as a terminal electrode of a multilayer ceramic electronic component. That is, for example, when the content ratio of the Cu material having a large particle size in the conductive paste is high, the inside of the terminal electrode after baking becomes porous, which may cause a problem in reliability such as moisture resistance. Further, for example, when the content ratio of the glass frit in the conductive paste is high, when glass is deposited on the surface of the terminal electrode and a plating film is formed on the terminal electrode after baking, there is a possibility that a plating seal failure may occur. is there.

Next, one embodiment of the multilayer ceramic electronic component of the present invention will be described in detail with reference to FIG. That is, the ceramic electronic component 1 includes the ceramic laminate 2, the internal electrodes 3 and 3, the terminal electrodes 4 and 4, and the plating films 5 and 5.

The ceramic laminate 2 is formed by firing a green ceramic laminate in which a plurality of ceramic layers 2a made of a dielectric material containing BaTiO ³ as a main component are laminated.

The internal electrodes 3, 3 are located between the ceramic layers 2a in the ceramic laminate 2, and a conductive paste is printed on the plurality of green ceramic layers 2a and fired simultaneously with the green ceramic laminate. Each edge of the internal electrodes 3 is formed so as to be exposed at any end face of the ceramic laminate 2.

The terminal electrodes 4 and 4 are made of a conductive paste containing Cu as a conductive component so as to be electrically and mechanically joined to one ends of the internal electrodes 3 and 3 exposed on the end faces of the ceramic laminate 2. Is applied to the end face of the ceramic laminate 2 and baked.

The plating films 5 and 5 are made of, for example, electroless plating of Sn or Ni, solder plating, etc., and are formed on the terminal electrodes 4 and at least one layer.

The material of the ceramic laminate 2 of the ceramic electronic component of the present invention is not limited to the above embodiment, but may be PbZrO ₃ or other dielectric materials, insulators, magnetic materials, piezoelectric materials. Also, it may be made of a semiconductor material. Further, the number of the internal electrodes 3 of the multilayer ceramic electronic component of the present invention is not limited to the above-described embodiment, and does not necessarily have to be provided, and any number of layers may be formed. Further, the plating films 5 and 5 are not necessarily required to be provided, and any number of layers may be formed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As one embodiment of the multilayer ceramic electronic component,
Rated voltage 50V, capacitance 10nF, length 2.00mm
A multilayer ceramic capacitor having a size of 1.25 mm in width and 0.60 mm in thickness is manufactured.

First, a raw ceramic layer containing BaTiO ₃ as a main component is prepared, and one edge of the raw ceramic layer is exposed on one of the end surfaces of the raw ceramic layer on the surface of a predetermined number of raw ceramic layers. Then, an electrode film to be an internal electrode containing Ni as a conductive component was printed thereon, and a predetermined number of these green ceramic layers were stacked and pressed to prepare a plurality of green ceramic bodies. Next, this was fired at 1300 ° C. in a reducing atmosphere to obtain a plurality of ceramic laminates.

Next, a spherical Cu powder having an average particle size of 1.0 μm and a spherical Cu powder having an average particle size of 3.0 μm
A powder and a flat Cu powder having an average particle size of 15.0 μm are prepared, and these are mixed at a weight ratio of 40: 20: 6.7 to obtain a Cu powder (class A). Was. Similarly, a spherical Cu powder having an average particle size of 0.5 μm,
A flat Cu powder having an average particle size of 3.0 μm was prepared, and these were mixed at a weight ratio of 55: 3 to obtain a Cu powder (B type).

Next, Cu powder (types A and B) and barium borosilicate glass frit were blended in the proportions shown in Table 1, and an acrylic resin, butyl carbitol,
An organic vehicle containing terpineol was prepared, and these were blended and kneaded to obtain conductive pastes of Samples 1 to 11.

Next, the above-mentioned conductive paste is applied to both longitudinal end surfaces of the above-mentioned ceramic laminate,
After baking at 700 to 800 ° C. in a reducing atmosphere to form a pair of terminal electrodes, a Ni plating film is formed on the terminal electrodes by electroplating, and a Sn plating film is further formed thereon. Thus, multilayer ceramic capacitors of Samples 1 to 11 were obtained.

Then, the Young's modulus of the terminal electrodes of the multilayer ceramic capacitors of Samples 1 to 11 and the sealing performance with plating were measured, and these are summarized in Table 1. As described above, the Young's modulus was measured by obtaining a load unloading curve of a load using a microhardness tester. The sealing performance with plating is determined by cutting the multilayer ceramic capacitor in the length direction and judging by the state of penetration of the plating solution into the terminal electrodes. Attached.

Further, the laminated ceramic capacitors of Samples 1 to 11 were measured to have a length of 100 mm × a width of 40 mm × a thickness of 1.6 m.
m on the land at the center of the glass epoxy substrate
/ Pb eutectic solder was used to prepare bending test samples of Samples 1 to 11, and the bending strength was measured. The flexural strength is measured by supporting both ends of the glass epoxy substrate in accordance with the EIAJ evaluation method, and pressing the glass epoxy substrate toward the front surface from the center rear surface using a push rod to bend the glass epoxy substrate. The moving distance (mm) of the push rod at the time when cracks occurred in the multilayer ceramic capacitors of Samples 1 to 11 mounted on the substrate was measured.

[0027]

[Table 1]

As is apparent from Table 1, the Young's modulus is
1.00 × 10^Ten~ 4.00 × 10 ^TenN / m^TwoWithin range
The multilayer ceramic capacitors of samples 3 to 5 and 11
Has excellent plating sealing properties and a flexural strength of 6.56 to 7.
It was strongly excellent at 84 mm. In particular, the Young's modulus is 1.02-
2.28 N / m^TwoSample 4,5,11 laminated ceramic
The flex capacitor has a flexural strength of 7.50 to 7.84 mm.
This is a particularly excellent range of the present invention.

On the other hand, the Young's modulus is 4.00 × 10
The multilayer ceramic capacitors of Samples 1, ^{2, 8} to ¹⁰ exceeding ¹⁰ N / m ² have excellent plating sealing properties, but have a weak flexural strength of 2.20 to 5.23 mm, and have a low flexural strength.
Since they were inferior to the multilayer ceramic capacitors of Nos. 5 and 11, they were outside the scope of the present invention.

The Young's modulus is 1.00 × 10 ¹⁰ N / m
The multilayer ceramic capacitors of Samples 6 and 7 below ² are:
The flexural strength was 7.23 to 7.45 mm, which was excellent, but the plating sealability was poor, and was out of the range of the present invention.

[0031]

As described above, in the multilayer ceramic electronic component according to the present invention, a ceramic laminate in which a plurality of ceramic layers are in a laminated state, and edges of the ceramic laminate are exposed at any one end face of the ceramic laminate. A plurality of internal electrodes formed between the ceramic layers, and a terminal electrode having a conductive component of Cu provided so as to be electrically connected to the edge of the internal electrode, and the Young's modulus of the terminal electrode is , 1.00
By being in the range of × 10 ^{10 to} 4.00 × 10 ¹⁰ N / m ² ,

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multilayer ceramic electronic component according to one embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 multilayer ceramic electronic component 2 ceramic laminate 2 a ceramic layer 3 internal electrode 4 terminal electrode

Claims (1)

[Claims] 1. A ceramic laminate in which a plurality of ceramic layers are stacked, and a plurality of internal electrodes formed between the ceramic layers such that respective edges are exposed at any one end face of the ceramic laminate. A terminal electrode having Cu as a conductive component provided so as to be electrically connected to an edge of the internal electrode, wherein the Young's modulus of the terminal electrode is 1.00. × 10 ^{10 to} 4.0
A multilayer ceramic electronic component characterized by being in the range of 0 × 10 ¹⁰ N / m ² .