JP2001338828A - Laminated electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated electronic part having an improved product of CR and insulation resistance reduced in properties depending on electric field intensity. SOLUTION: Dielectric layers and inner electrode layers are alternately laminated into an electronic part main body, a pair of outer electrodes which are alternately connected to the inner electrode layers is provided to the edge faces of the electronic part main body for the formation of a laminated electronic part. The above dielectric layers contain 10 to 30 vol.% crystal grains of 0.4 μm diameter or above and 50 to 70 vol.% crystal grains of 0.25 μm diameter or below, by which a product of CR can be improved, and insulation resistance can be reduced in properties depending on electric field intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electronic component, and more particularly to a laminated electronic component used for small and high-performance electronic equipment such as a cellular phone, which is formed by alternately laminating extremely thin dielectric layers and internal electrode layers. The present invention relates to a small and large-capacity laminated electronic component.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and higher in density, multilayer electronic components, for example, multilayer ceramic capacitors, have been required to have smaller sizes and larger capacities. The thickness of the dielectric layer itself has been reduced.

As such a multilayer ceramic capacitor, for example, one disclosed in Japanese Patent Application Laid-Open No. 11-317322 has been known. The multilayer ceramic capacitor disclosed in this publication has an average particle size of 3.5 μm.
m of BaTiO ₃ -based ceramic particles having a thickness of 5 μm or more, the ratio of one ceramic particle in one dielectric layer is 2%.
A multilayer ceramic capacitor is formed by alternately laminating a dielectric layer formed to be 0% and internal electrodes mainly composed of Ni powder.

According to such a configuration, even in a laminated ceramic capacitor formed by laminating dielectric layers each having a thickness of 5 μm, CR product (capacitance C × insulation resistance R), which is one of the characteristics of the capacitor. ) Can be increased.

[0005]

In general, the CR product of a multilayer ceramic capacitor is a value that does not depend on the thickness or the number of dielectric layers. As described above, when the thickness of the dielectric layer is further reduced in order to increase the capacity of the multilayer ceramic capacitor, and the thickness of the dielectric layer becomes extremely thin as 2.5 μm or less, the insulation resistance of the dielectric obeys Ohm's law. Therefore, there is a problem that the CR product is further reduced.

Further, the multilayer ceramic capacitor disclosed in the above publication has a dielectric layer having a thickness of 5 μm,
In this case, although having a high CR product, there is a problem that as the thickness of the dielectric layer becomes thinner, the insulation resistance becomes smaller, and the electric field strength of the insulation resistance becomes lower.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a multilayer electronic component that can improve the dependence of the CR product and the insulation resistance on the electric field strength.

[0008]

According to the laminated electronic component of the present invention, a pair of external electrodes are formed at both ends of an electronic component main body in which dielectric layers and internal electrode layers are alternately laminated. In the multilayer electronic component, the dielectric layer has a particle size of 0.4
It contains 10 to 30% by volume of large-diameter crystal particles having a diameter of not less than μm and 50 to 70% by volume of small-diameter crystal particles having a particle diameter of not more than 0.25 μm.

According to such a configuration, the dielectric constant of the dielectric is individually increased by the large-diameter crystal particles having a particle diameter of 0.4 μm or more contained in the dielectric layer, and the electrostatic property of the multilayer electronic component is increased. The capacity can be improved, and the small-diameter crystal grains having a grain size of 0.25 μm or less can increase the insulation resistance of the dielectric due to the insulating properties of a large number of grain boundary phases contained therein.
When a dielectric having a microstructure in which both of these crystal grains are mixed is formed, the CR product can be improved as compared with the case where the large crystal grains and the small crystal grains are used alone. Further, as the thickness of the dielectric layer becomes smaller, the insulation resistance decreases, and the electric field strength dependence of the insulation resistance is large. However, in the multilayer electronic component of the present invention, small-diameter crystal grains exist around large-diameter crystal grains. This makes it possible to reduce the electric field strength dependency of the insulation resistance R.

In the above-mentioned laminated electronic component, 90% of large-diameter crystal grains having a diameter of 0.4 to 0.6 μm are included in the large-diameter crystal grains.
Volume% or more, among the small crystal grains, the particle size is 0.1 to 0.1.
It is desirable to include 90 volume% or more of small-diameter crystal grains of 25 μm. According to this configuration, the dielectric layer has a particle size distribution in which large-diameter crystal grains and small-diameter crystal grains are almost clearly separated, so that the CR product can be further improved, and the electric field strength dependence of insulation resistance is further reduced. In this case, the dielectric layer can have both the dielectric and insulating characteristics of both crystal grains.

In the above-mentioned laminated electronic component, it can be suitably used when the thickness of the dielectric layer is 2.5 μm or less. In this case, the dielectric layer can be made thinner, and even if the thickness becomes 2.5 μm or less, a large-capacity, high-insulation multilayer electronic component can be provided.

In the above-mentioned multilayer electronic component, the dielectric layer is made of Ba.
It preferably contains TiO ₃ , Mn and a rare earth element. Among these dielectric materials, it is possible to increase the dielectric constant of the dielectric layer thinned with BaTiO ₃ , and to crystallize the dielectric layer fired in a reducing atmosphere with Mn and a rare earth element. A high-insulating dielectric layer can be obtained by generating a grain boundary phase while suppressing the crystal growth of and suppressing the reduction reaction of the dielectric.

In the above-mentioned laminated electronic component, it is desirable that the internal electrode layer and the external electrode layer are at least one selected from base metal elements. For example, as the internal electrode layer, N
By using i or Cu, Pt or P
The manufacturing cost can be reduced as compared with a noble metal such as d. Also, for the external electrode, in addition to using Ni or Cu alone, for example, by using an alloy of Ni and Cu, the oxidation resistance of the external electrode is increased, and not only solder but also organic resin is contained. Adhesive bonding with the conductive paste can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Structure) A multilayer ceramic capacitor which is a multilayer electronic component A according to the present invention will be described in detail with reference to the schematic sectional view of FIG. The multilayer electronic component A of the present invention is configured by forming external electrodes 3 on both ends of the electronic component body 1. This external electrode 3 is made of, for example, Cu
Alternatively, it is formed by baking an alloy paste of Cu and Ni. The electronic component body 1 is provided on both sides in the laminating direction of the capacitor portion 9 in which the internal electrode layers 5 and the dielectric layers 7 are alternately laminated.
An insulating layer 11 made of the same material as the dielectric layer 7 is formed. In addition, for example, a Ni plating layer 13, a Sn plating layer, or a Sn—Pb
An alloy plating layer 15 is formed. These are to prevent the solder erosion of the external electrode 3 and to supplement the solder wettability.

On the other hand, the internal electrode layer 5 is formed of a metal film obtained by sintering a conductive paste film. As the conductive paste, for example, a base metal such as Ni, Co, or Cu is used. The internal electrode layer 5 is a substantially rectangular conductor film containing a base metal as a main component, and has a first layer, a third layer,
One end of each of the fifth-layer odd-numbered internal electrode layers 5 is exposed at one end surface of the capacitor body 1, and the second, fourth, sixth,... The internal electrode layer 5 of
One end is exposed on the other end surface of the capacitor body 1. Note that the external electrode 3 and the internal electrode layer 5 do not necessarily need to be made of the same material.

As shown in detail in FIG. 2, the dielectric layer 7 which is a main part of the multilayer electronic component A according to the present invention includes large crystal grains 17 having a grain size of 0.4 μm or more. In addition, small crystal grains 19 having a grain size of 0.25 μm or less are densely mixed via the grain boundary phase 21 to form a microstructure in which crystal growth is appropriately controlled. That is, the small crystal grains 19 are arranged so as to surround the large crystal grains 17.

The ratio of the large-diameter crystal grains 17 to the small-diameter crystal grains 19 in the dielectric layer is such that the particle diameter is 0.4 μm.
The large crystal grains 17 are present in an amount of 10 to 30% by volume, and the small crystal grains 19 having a particle size of 0.25 μm or less are present in an amount of 50 to 70% by volume.

In order to exhibit a high dielectric constant as a dielectric layer used in a multilayer electronic component, for example, a multilayer ceramic capacitor, the diameter of the large-diameter crystal grains 17 is 0.4 μm.
m or more, and the particle size of the small-diameter crystal particles 19 is preferably 0.25 μm or less in order to increase the insulation resistance of the dielectric. And, among these crystal particles, a particle size of 0.4 μm
By mixing 10 to 30% by volume of large-diameter crystal particles 17 having a diameter of m or more and 50 to 70% by volume of small-diameter crystal particles 19 having a particle diameter of 0.25 μm or less, C
The R product can be increased, and the dependence of the insulation resistance on the electric field strength can be suppressed.

In particular, the proportion of the large crystal grains 17 having a particle size of 0.4 to 0.6 μm is 90% by volume or more, and the small crystal grains 19 have a particle size of 0.1 to 0.25 μm. When the ratio is 90% by volume or more, the CR product is increased, and the electric field strength dependence of the insulation resistance is further suppressed.
Desirable in terms of stabilization. One sheet-shaped dielectric layer composed of these crystal grains has a thickness of 2.5 μm.
m or less. For example, for the multilayer electronic component A,
In order to increase the capacity of a multilayer ceramic capacitor, it is effective to make the dielectric layer thinner, and in order to construct a small-sized, high-capacity multilayer ceramic capacitor in recent years, the thickness of the dielectric layer has to be increased. Is preferably 2.0 to 2.5 μm.

The dielectric layer 7 is made of a sheet-shaped ceramic sintered body, and may be made of a so-called ferroelectric ceramic material having a perovskite-type crystal structure. In particular, BaTiO ₃ , A dielectric ceramic composition containing Mn and a rare earth element;
O _3, Y ₂ O ₃ rare earth elements such as, MgO, and MnCO _3, they are preferably made of low-temperature sintering aid such as glass. By adjusting and including these dielectric materials, the sinterability and reduction resistance of the dielectric ceramic can be improved.

(Manufacturing Method) In the multilayer electronic component A of the present invention, first, a green sheet to be a dielectric is prepared. This green sheet includes, for example, two or more types of B having a large specific surface area.
It can be formed using aTiO ₃ raw material powder, and the method for synthesizing the main raw material BaTiO ₃ powder includes a solid phase method, a liquid phase method (such as passing through oxalate), and a hydrothermal synthesis method. Of these, hydrothermal synthesis is preferred because of its narrow particle size distribution and high crystallinity. The specific surface area of the BaTiO ₃ powder is 1.7~6.6 (m ² / g) are preferable.

Next, an electrode pattern of the internal electrode layer 5 made of a conductive paste is printed on the green sheet and dried. Next, a plurality of the green sheets are laminated and thermocompression-bonded. Thereafter, the laminate is cut into a lattice to obtain a molded body of the electronic component body 1. The ends of the electrode pattern of the internal electrode layer 5 are alternately exposed on both end surfaces of the electronic component body 1.

Next, the multilayer electronic component body 1 is subjected to a binder removal treatment at 200 to 450 ° C. in the air, and then fired at a temperature of 1200 to 1290 ° C. for 2 hours. A reoxidation treatment is performed at 1050 ° C.

The external electrodes 3 are formed by applying an external electrode paste to both end surfaces of the fired capacitor body and baking the paste in nitrogen.

Further, the surface of the external electrode 3 is degreased, acid-washed,
After washing with pure water, the barrel method
Plating, Sn plating or Sn-Pb alloy plating is performed.

(Function) In the multilayer electronic component A configured as described above, the large-diameter crystal particles 17 having a thickness of 0.4 μm or more forming the dielectric layer 7 having a thickness of 2.5 μm or less are used.
Is contained in an amount of 10 to 30% by volume and 50 to 70% by volume of small crystal grains 19 having a particle size of 0.25 μm or less, thereby improving the CR product of the multilayer electronic component and the electric field of insulation resistance. In terms of suppressing strength dependence, the performance of the multilayer electronic component can be dramatically improved.

Further, as described above, by using BaTiO ₃ powder having a large specific surface area for the dielectric material amount of the multilayer electronic component, for example, the multilayer ceramic capacitor,
The firing temperature can be reduced, and the manufacturing cost can be reduced.

[0028]

EXAMPLE A multilayer ceramic capacitor, which is one of multilayer electronic components, was manufactured as follows. First, as a dielectric element material, the specific surface area is 1.7, 3.2, 6.6 (m
² / g) and three types of BaTiO ₃ powder,
1 part by weight of Y ₂ O ₃ per 100 parts by weight of iO ₃ , Mg
0.2 parts by weight of O, 0.1 parts by weight of MnCO ₃ , Li ₂
A raw material powder containing 0.5 part by weight of a glass component composed of O and SiO ₂ (the molar ratio of Li to Si is 1: 1) was used to obtain a powder having a diameter of 5
It was prepared by wet pulverization in a ball mill using ZrO ₂ balls of mmφ.

Next, these three types of powders were blended in the proportions shown in the formulation examples in Table 1, and then mixed with an organic binder to prepare a slurry, and a green sheet was prepared by a doctor blade.

Next, an internal electrode paste composed of Ni powder, ethylcellulose and terpineol was screen-printed on the green sheet. The effective area of this internal electrode layer was 2.1 mm ² .

Next, 100 green sheets on which the internal electrode paste was printed were laminated, and 20 green sheets on which the internal electrode paste was not printed were respectively placed on the upper and lower surfaces.
The sheets were laminated and integrated using a hot press machine to obtain a laminate.

Thereafter, the laminate is cut into a lattice shape.
A molded body of the capacitor body 1 having a size of 3 mm × 1.5 mm × 1.5 mm was produced.

Next, the molded body of the capacitor body is subjected to a binder removal treatment at 400 ° C. in the air.
The capacitor body was fired at 10 ° C. to 1290 ° C. (oxygen partial pressure: 10 ⁻¹¹ atm) for 2 hours, and then re-oxidized at 1000 ° C. in an air atmosphere to obtain a fired capacitor body.

Next, after the fired capacitor body 1 is barrel-polished, an external electrode paste containing Cu powder and glass is applied to both ends of the capacitor body and baked at 850 ° C. in nitrogen to form external electrodes. did. Then, using an electrolytic barrel machine, Ni and Sn plating were sequentially performed on the surface of the external electrode to produce a laminated electronic component. The following evaluation was performed on the multilayer electronic component obtained as described above.

First, the capacitance was measured at a frequency of 1.0 kHz and an input signal level of 1.0 Vrms. Thereafter, a DC voltage of 10 V was applied for one minute, and the insulation resistance was measured.
The R product was calculated.

Next, after performing an aging treatment at a temperature of 150 ° C. where the dielectric properties of the dielectric layer show paraelectricity,
The insulation resistance was measured under an applied voltage of 30 V for one minute. Subsequently, 30 V with respect to the insulation resistance at an applied voltage of 10 V
Was calculated, and the electric field strength dependence of the insulation resistance was evaluated. In the multilayer electronic component evaluated in this manner, a non-defective product having a CR product of 3000ΩF or more and an insulation resistance ratio of 0.1 or more was evaluated as good.

In measuring the crystal grain size of the dielectric layer, the interface of the dielectric layer obtained by peeling the internal electrode layer of the multilayer electronic component was photographed at a magnification of 2000 times using a scanning electron microscope. From the photograph, the dimensions of the crystal grains of the ceramic crystal grains in a certain area were measured by the intercept method. The volume ratio of the crystal grains contained in the dielectric layer was determined by dividing the large crystal grains of 0.4 μm or more and the small crystal grains of 0.25 μm or less among the crystal grains whose particle diameters were measured using an image analyzer. It was evaluated by sorting.

[0038]

[Table 1]

As is clear from the results shown in Table 1, among the multilayer ceramic capacitors using the dielectric layer having a thickness of 2.5 μm, large crystal grains having a diameter of 0.4 μm or more are 10 to 3 times.
0 volume% and small crystal grains having a diameter of 0.25 μm or less
0% by volume and fired at a temperature of 1250 ° C. or less. 2, 3, 4, 5, 6, 9, 10, 11, 12, 1,
In the case of No. 3, the CR product showed a value of 3000 ΩF or more (Sample Nos. 2 to 6 and 9 to 13), and the insulation resistance ratio could be increased to 0.1 or more. Was able to greatly improve the dielectric properties.

In particular, large crystal grains of 0.4 μm or more
Sample No. 2 containing 0% by volume and 62% by volume of small-diameter crystal particles of 0.25 μm or less and fired at a temperature of 1230 ° C. 11
In the multilayer ceramic capacitor having a dielectric layer of 2.5 μm, the highest CR product was obtained, and a conventionally used sample using a dielectric layer having one peak of particle size distribution (sample No. 23) As compared with the case of (2), when the thickness of the dielectric layer was 2.5 μm, the decrease in the insulation resistance with respect to the change in the voltage was suppressed.

Further, the thickness of the dielectric layer is set to 2.0 to 5.0 μm.
m. In Nos. 18 to 22, the CR product was improved with an increase in the thickness of the dielectric layer. In particular, even when the thickness of the dielectric layer of the present invention was extremely reduced to 2.0 μm (Sample No. 18), , CR product and insulation resistance ratio could be maintained high. On the other hand, Sample No. containing less than 10% by volume or more than 30% by volume of large-diameter crystal particles, or less than 50% by volume or more than 70% by volume of small-diameter crystal particles.
In 1, 7, 8, 14, 15, 16, and 17,
The CR product was 3000ΩF or less.

Further, as shown in FIG.
m, except for the small-diameter crystal particles having a diameter of 0.4 μm or less. In Examples 23 and 24, the CR product could be increased, but when the thickness of the dielectric layer was 2.5 μm, the insulation resistance ratio was reduced, and the electric field strength dependence of the insulation resistance was increased.

[0043]

As described above, in the multilayer electronic component of the present invention, the dielectric layer is composed of 10 to 30% by volume of large-diameter crystal grains having a grain size of 0.4 μm or more and small-diameter grains having a grain size of 0.25 μm or less. By containing the crystal particles at a ratio of 50 to 70% by volume, the CR product of the multilayer electronic component can be increased, and the electric field strength dependence of the insulation resistance can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a multilayer electronic component of the present invention.

FIG. 2 is a cross-sectional view showing a microstructure of a dielectric used in the multilayer electronic component of the present invention.

FIG. 3 is a graph showing electric field strength dependence of insulation resistance of a multilayer electronic component.

[Explanation of symbols]

 A Laminated electronic component 1 Electronic component body 3 External electrode 5 Internal electrode layer 7 Dielectric layer 17 Large crystal grain 19 Small crystal grain 21 Grain boundary phase

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E001 AB03 AC09 AD00 AE02 AE03 AE04 AF06 5E082 AA01 AB03 BC14 EE04 EE23 EE35 FG06 FG26 FG54 GG10 GG11 GG28 JJ03 JJ12 JJ15 JJ23 MM24 PP09

Claims (5)

[Claims] 1. A laminated electronic component comprising a pair of external electrodes alternately connected to said internal electrode layers formed at both ends of an electronic component body comprising alternately laminated dielectric layers and internal electrode layers. In the above, the dielectric layer contains 10 to 30% by volume of large-diameter crystal particles having a particle diameter of 0.4 μm or more, and 50 to 70% of small-diameter crystal particles having a particle diameter of 0.25 μm or less.
A multilayer electronic component characterized in that it is contained in a volume percentage. 2. The large-diameter crystal particles having a particle size of 0.4 to 0.1.
It is characterized by containing 90% by volume or more of the large-diameter crystal particles of 6 μm and 90% by volume or more of the small-diameter crystal particles having a particle size of 0.1 to 0.25 μm among the small-diameter crystal particles. The multilayer electronic component according to claim 1. 3. The multilayer electronic component according to claim 1, wherein the thickness of the dielectric layer is 2.5 μm or less. 4. The multilayer electronic component according to claim 1, wherein the dielectric layer contains BaTiO ₃ , Mn, and a rare earth element. 5. The multilayer electronic component according to claim 1, wherein the internal electrode layer and the external electrode are made of a base metal.