JPH1012477A - Lamination ceramics electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discourage breakage of an internal electrode and to facilitate recovery of the broken internal electrode to a connection state by specifying a minimum dimension ratio of the internal electrode thickness in a specific range as in maximum dimension of it. SOLUTION: By grinding an LT surface of a ceramics lamination body 1, an internal electrode 2 inside the ceramics lamination body 1 is exposed. Then the thickness of an arbitrary internal electrode 2 is measured. With maximum dimension of its thickness as tMAX and minimum one as tMIN, tMAX/tMIN is so selected that tMAX/tMIN <=10. More favorably, tMAX<=4.0μm and tMIN>=0.3μm. Thereby, a desired electric capacity is obtained, with less dispersion, and occurrence of delamination is suppressed.

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 having a ceramic laminate in which a plurality of internal electrodes are laminated via a ceramic layer, and more particularly to a method for optimizing the thickness of internal electrodes. Technology.

[0002]

2. Description of the Related Art FIG. 1 shows a ceramic laminate 1 for a multilayer ceramic capacitor as an example of a multilayer ceramic electronic component of interest to the present invention.
The ceramic laminate 1 has an L-direction dimension, a W-direction dimension, and a T-direction dimension. FIG. 2 shows a state in which a plurality of internal electrodes 2 provided on the ceramic laminate 1 are exposed by polishing the LT surface defined by the dimensions in the L and T directions of the ceramic laminate 1 shown in FIG. It is shown.

In a ceramic laminate 1, a plurality of internal electrodes 2 are laminated via a ceramic layer 3. Some of these internal electrodes 2 are drawn out to one of the opposing end faces 4 and 5 of the ceramic laminate 1, and others are drawn out to the other, and these are arranged alternately. In order to form a multilayer ceramic capacitor using such a ceramic laminate 1,
External electrodes (not shown) are formed so as to cover end surfaces 4 and 5 of ceramic laminate 1, respectively. Internal electrode 2
Are connected to any of these external electrodes.

In order to obtain the above-mentioned ceramic laminate 1,
A ceramic green sheet containing a ceramic powder and an organic substance such as an organic binder is prepared. This ceramic green sheet becomes the ceramic layer 3. On the other hand, noble metals (platinum,
Palladium, silver, etc.) or base metals (nickel, copper,
Etc.) and a conductive paste containing an organic substance. Next, a raw ceramic laminate 1 is obtained through a step of applying a conductive paste in a predetermined pattern on the ceramic green sheets and a step of laminating such a plurality of ceramic green sheets.

[0005] Thereafter, the raw ceramic laminate 1 is
First, it is degreased in the binder removal process, organic matter is removed,
Next, in the case of a conductive paste containing a noble metal,
In the case of a conductive paste containing a base metal in an oxidizing atmosphere, firing is performed in a reducing atmosphere.

In this way, a fired ceramic laminate 1 is obtained. In the above-described firing step, after the organic substances are removed, the metal powder contained in the conductive paste is reduced to 7%.
Sintered in a temperature range of 00 to 1100 ° C., and the ceramic powder contained in the ceramic green sheet is 1200
Sinter in a temperature range of １1400 ° C. At the time of sintering, the metal powder and the ceramic powder apparently shrink, respectively.

[0007]

When the degree of shrinkage of the above-mentioned metal powder is too large, the internal electrode 2 is cut off in the obtained ceramic laminate 1 and the effective electrode area is reduced. One encounters the problem of reduced capacitance.

On the other hand, the shrinkage of the ceramic starts after the above-described shrinkage of the metal is completed. The shrinkage of the ceramic acts to restore the internal electrode 2 that has caused the disconnection to the connected state again. However, if the degree of shrinkage of the ceramic is small, the internal electrode 2 cannot be restored to the connected state, and the electrostatic force cannot be restored. There is no hope of recovering the capacity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multilayer ceramic electronic component that has a condition that makes it difficult for the internal electrode to be cut and that easily recovers the connection state of the internal electrode that has caused the cut. That is.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to a multilayer ceramic electronic component having a ceramic laminate in which a plurality of internal electrodes are laminated via a ceramic layer. To solve the problem, when the maximum dimension of the thickness of the internal electrode is t _MAX and the minimum dimension is t _MIN , t _MAX / t _MIN becomes t _MAX / t _MIN.
The selection is made to be within the range of ≦ 10.

[0011] In the present invention, preferably, t _MAX is t _MAX ≦ 4.0μm, t _MIN is selected so that the respective ranges of t _MIN ≧ 0.3 [mu] m.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is not limited to a multilayer ceramic capacitor, but is applicable to a multilayer ceramic varistor and the like, as long as it is a multilayer ceramic electronic component having a ceramic laminate in which a plurality of internal electrodes are laminated via a ceramic layer. The present invention can be equally applied to other multilayer ceramic electronic components. Hereinafter, the description of the embodiment of the present invention,
This is performed in connection with the multilayer ceramic capacitor formed using the ceramic laminate 1 shown in FIGS. 1 and 2 described above.

FIG. 2 is an enlarged view of a portion surrounded by a circle III in FIG. 2 in which the LT surface of the ceramic laminate 1 shown in FIG. 1 is polished to expose the internal electrodes 2 inside the ceramic laminate 1. Is shown in FIG. As shown in FIG.
When the thickness of an arbitrary internal electrode 2 is measured and the maximum dimension of the thickness is defined as t _MAX and the minimum dimension is _defined as t _MIN , t
_MAX / t _MIN is chosen to be in the range t _MAX / t _MIN ≦ 10. Further, more preferably, t _MAX is t _MAX
≦ 4.0 μm, and t _MIN is selected to be in each range of t _MIN ≧ 0.3 μm.

The maximum dimension t of the thickness of such an internal electrode 2
_The conditions regarding _MAX and the minimum dimension t _MIN were obtained from experiments described later. In these experiments, these conditions have a correlation with the obtained capacitance and the delamination occurrence rate of the multilayer ceramic capacitor. It was found. That is, among the multilayer ceramic capacitors obtained by the experiment, those which were excellent with respect to the obtained capacitance, as a result, t _MAX / t _MIN
≦ 10, and t _MIN ≧ 0.3 μm,
Moreover, what was excellent with respect to the acquired capacitance and the delamination occurrence rate, as a result, t _MAX / t _MIN ≦
10, and each condition of t _MAX ≦ 4.0 μm was satisfied.

In the experiments described below, the metal content in the conductive paste for forming the internal electrodes 2 was changed (Experimental Example 1), and the binder and plasticizer in the ceramic green sheet for forming the ceramic layer 3 were used. Changing the addition ratio of organic substances including water, dispersants, etc. (Experimental example 2)
Then, various multilayer ceramic capacitors were manufactured, the capacitance and the delamination occurrence rate of these multilayer ceramic capacitors were evaluated, and as shown in FIGS. 2 and 3, the internal electrodes 2 were exposed, t
_MAX and t _MIN were measured and t _MAX / t _MIN was determined.

(Experimental Example 1) In Experimental Example 1, the metal content in the conductive paste for forming the internal electrode was:
Although it was selected to be 45 to 65 wt% by empirical rules, based on this result, the range of the optimum value that does not cause disconnection of the internal electrode is determined from the result.

Samples 1 to 11 were prepared by changing the metal content [wt%] in the conductive paste for forming the internal electrodes as shown in Table 1 below. t _MIN [μm], t _MAX [μm], t _MAX / t
_MIN , the average value [nF] and the variation [%] of the capacitance, and the delamination occurrence rate [%] are obtained, and the overall evaluation is 〇 (good), △ (not very good), × (bad). In three stages. The organic substance addition ratio of the ceramic green sheet was constant at 13 wt% for each sample.

[0018]

[Table 1]

As shown in Table 1, in samples 1 to 3, t
_MAX / t _MIN exceeds 10, and in this case, only a small capacitance is obtained. In particular, samples 1 and 2
In the case of t _MAX / t _MIN greatly exceeding 10, as in the above, the capacitance is considerably small, and the overall evaluation is “×”.
It has been. In samples 1 to 3, the metal content was 3%.
5 wt% or less, so that t _MIN is less than 0.3 μm. This is considered to be the cause of the decrease in capacitance.

On the other hand, for the samples 4 to 11 satisfying t _MAX / t _MIN ≦ 10, a large capacitance is obtained and the variation is small. From this, in order to secure a large capacitance, that is, a desired capacitance, the metal content of the conductive paste for the internal electrode can be selected so as to satisfy the condition of t _MAX / t _MIN ≦ 10. It turns out that it is good. For t _MIN , samples 4-1
No. 1 satisfies the condition of t _MIN ≧ 0.3 μm.

When the metal content is 70 wt% or more, as in the samples 10 and 11, the difference in shrinkage between the internal electrode and the ceramic layer increases, and delamination occurs. In particular, when the metal content is 80 wt% as in Sample 11, the delamination occurrence rate is 24%.
%, And the overall evaluation is "x". These samples 1
Focusing on t _{MAX of} 0 and 11, both 4.0 μm
m, and therefore it is more preferable to satisfy the condition of t _MAX ≦ 4.0 μm.

From these facts, the metal content of the conductive paste for the internal electrode was 40% as in Samples 4 to 9.
It can be said that the content is preferably in the range of wt% to 65 wt%.

(Experimental Example 2) In Experimental Example 2, if the shrinkage of the ceramic green sheet is increased by increasing the amount of organic substances in the ceramic green sheet, that is, by decreasing the density of the ceramic green sheet, It is intended to confirm that the cut of the electrode can be recovered.

In the ceramic green sheet, the addition ratio [w of an organic substance including a binder, a plasticizer and a dispersant]
t%] was varied as shown in Table 2 below to prepare samples 12 to 24, and t _MIN [μ
m], t _MAX [μm], t _MAX / t _MIN , the average value [nF] and variation [%] of the capacitance, and the delamination occurrence rate [%], respectively. ), Δ (not very good), and × (bad). The metal content of the conductive paste for the internal electrode was fixed at 50 wt% in each sample.

[0025]

[Table 2]

As shown in Table 2, all of the samples 12 to 24 satisfy the condition of t _MAX / t _MIN ≦ 10.

However, for samples 12 and 13 having t _MIN less than 0.3 μm, the capacitance is considerably small and the overall evaluation is “x”. Also, the sample 3 having a t _MIN of 0.32 μm has a relatively small capacitance, and the overall evaluation is “△”.

On the other hand, delamination has occurred in samples 22 to 24 having t _MAX exceeding 4.0 μm. Here, the delamination occurrence rate is 1
%, The overall evaluation is “Δ”, and the samples 23 and 24 with delamination occurrence rates of 8% and 14% are “X”.

On the other hand, the samples 15 to 21 have a sufficient capacitance, a small variation, and no delamination. From these facts, the organic substance addition ratio of the ceramic green sheet was in accordance with Sample 15
It can be said that it is preferable to be in the range of 10 wt% to 16 wt% as in the case of 21.

[0030]

As described above, according to the present invention, the metal content of the conductive paste for the internal electrode and the organic material addition ratio of the ceramic green sheet are selected, and as a result, t _MAX / t _MIN becomes t _MAX. / T _MIN ≦ 10, more preferably, satisfying this condition.
A desired capacitance can be obtained by selecting conditions for the maximum size t _MAX and the minimum size t _MIN of the thickness of the internal electrode so that t _MAX ≦ 4.0 μm and t _MIN ≧ 0.3 μm. It is possible to obtain a multilayer ceramic electronic component in which the variation is small and the occurrence of delamination is suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a ceramic laminate 1 provided in a multilayer ceramic capacitor as an example of a multilayer ceramic electronic component that is of interest to the present invention.

FIG. 2 is a perspective view showing a state in which an LT surface of the ceramic laminate 1 shown in FIG. 1 is polished to expose an internal electrode 2;

FIG. 3 is an enlarged view showing a portion surrounded by a circle III in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ceramic laminated body 2 Internal electrode 3 Ceramic layer t _MAX Maximum dimension of internal electrode thickness t _MIN Minimum dimension of internal electrode thickness

Claims (2)

[Claims] 1. A multilayer ceramic electronic component comprising a ceramic laminate in which a plurality of internal electrodes are stacked via a ceramic layer, wherein the maximum dimension of the thickness of the internal electrodes is t _MAX , and the minimum dimension is t _MIN . Then, t _MAX / t _MIN becomes t _MAX
/ T _MIN ≦ 10, wherein the multilayer ceramic electronic component is characterized in that: 2. The method according to claim 1, wherein t _MAX is in a range of t _MAX ≦ 4.0 μm, and t _MIN is in a range of t _MIN ≧ 0.3 μm.
The multilayer ceramic electronic component according to claim 1.