JPS61251016A - Manufacture of laminate type ceramic element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a method for manufacturing a laminated ceramic element.

[Technical background of the invention and its problems] [BaTi0. dielectric materials are used. Recently, for the purpose of cost reduction, etc., development of composite perovskite-type dielectric materials using Pbf as an element that can be sintered at relatively low temperatures has been actively conducted.

For example, Pb[(Fe, /2Nb1/2) (Fe2
/3W 1/3n]0. system, P b ((Mj'1/
Various compositions such as 2W1/1Ti]O and the like are known.

In manufacturing a laminated ceramic element, a method is used in which raw ceramic sheets coated with electrode paste are laminated and integrally sintered. Conventional BaTiO3 systems require high sintering temperatures, so expensive materials such as Pd paste that can withstand the sintering temperature ζ have been used, but AI! A relatively low-cost paste can be used. For example, JP-A-58-192317
pbCFe 1/2Nb 1/2) 0.67
(F e 2/3 WIA) Os (D composite 40 busite dielectric l) The inside of the Ag-Pd system is covered with polar paste 1-
The method of forming is described in detail. JP-A-58-1
As shown in No. 92317, AII powder,
Pd powder is prepared separately and mixed with a suitable solvent to form a paste.

In such a conventional multilayer ceramic element, during firing, the Ag powder gradually forms an alloy with the Pd particles. At this time, in a region where a large amount of A, 9 powder exists, Ag diffuses along the grain boundaries of the ceramic, sometimes causing a short circuit. Also, when looking at Pd powder, it is 400 to 60.
At 0° C., it becomes palladium 1212, and at that time an abnormal volume change occurs, which may cause cracking, peeling, etc. in the dielectric. Sometimes, materials containing Pb2 of 30 wt or more in terms of PbO tend to cause a reaction between Pd and Pb, which poses a problem in terms of reliability.

Furthermore, the migration speed of A and 9 is much faster than that of Pd, so if there is a region with a large amount of Ag, insulation failure will occur in high temperature, high humidity, and low pressure conditions. There was a problem with sexuality.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and its entire purpose is to provide a method for manufacturing a highly reliable multilayer ceramic element that does not cause destruction or characteristic deterioration of the element during manufacturing or use.

[Summary of the invention]

In the present invention, when manufacturing a multilayer ceramic element t in which a dielectric material 1 made of a ceramic having a perovskite structure containing lead as a total constituent element and electrode layers are alternately stacked, a silver/palladium compound is formed during the formation of the electrode layer. , gold (hereinafter referred to as All-P
d alloy) This is a method for manufacturing a multilayer ceramic element characterized by using a conductive paste used as a total conductor powder.

The manufacturing process will be explained below in order.

First, it is a ceramic with a pebskite structure that contains lead as a constituent element, and is a pb'rto type ceramic.

pb'rto, -PbZr03 series, P, b (Fe
1/2Nb x, q) Os-based.

P b (ME 1/2 Wl/2) Os-based, Pb
(NitANbzA)Os system-Pb (FC2/aWx Han03 system, etc.), as well as composite systems of these, Pb
A part of Ca, Ba, Sr.

Substituted with La, etc., MnO, Coo, F
Examples include those to which transition metals such as e10g, lanthanides, etc. are added. Any type of system may be used, but if the system contains 30% by weight or more in terms of lead 1PbO, pb and i! The effect of the present invention is remarkable because the reaction of Pd in the polar layer is slow.

In particular, Pb (Zll/3Nb), which was developed earlier by the present inventors,
27s) The multilayer ceramic capacitor material in which Os is partially replaced with fBa and Sr can be sintered at low temperatures and has excellent electrical properties, and is suitable for use in the present invention. It is effective because it allows the @-group that has formed the group to take full advantage of its characteristics.

When the general formula of this system 1ABO, (P b
1-zMe X)(”n 1/3Nb2/3)Os(
0,1(x(0,35,M#=Ba,5r)(Pb t
-xMex)C(Z'nx/3Nbz/3)x-yTi
y)03(0,1(x<0.35, o<y<o,s
, Me=Ba, Sr)(Pbt-xMex)[
(Znt/3Nbz/a)l-z(MI 1.-3Nb
2/3 ) z ] 0H(0,01(x(0,35@
0<z(0,9,Me-Ba,5r)(P b 1-X
Mez ) ((Znt/aNb2/a)ty-
z(Ml!/3Nb2/3) z″lo.

(0,01(x(0,35, o<y<o, s, O(
z(0,9.

Me-Ba, Sr) In addition, MnO, CoO, NiO, MgO.

sb, o, , zro, , La, O, etc. (/J1wt
% hardness is also possible. In this system, Pbf at the A site: Me acid component P b (Z n 173
N b 2/3) is an essential component for forming a perovskite structure with Os. Therefore, the lower limit of the value of X in the above compositional formula is determined. If there are too many, it will be baked! The M degree becomes high, about 1100°C or more, and Ti, (Mg1/3Nb2/3), etc. at the B site are effective components for improving the dielectric constant, and adding a small amount does not produce this effect. However, each has a remarkable effect of 0.01 or more. Table 1 shows the initial characteristics of this system. dielectric constant, sleep loss,
It can be seen that various properties such as CR value and TCC are excellent.

) When manufacturing the multilayer ceramic element 1, the ceramic raw material powder is slurried with a binder, a solvent, etc., a green sheet is completely formed, and internal electrodes are printed on this green sheet. A predetermined number of sheets are laminated, crimped, and fired to manufacture the product.

The ceramic raw material powder is produced in two steps as shown below.

Pb, Ba, Sr, Zn, Nb, Ti as starting materials.

Oxides such as Mg, salts such as carbonates and oxalates that become oxides upon firing, hydroxides, organic compounds, etc. are weighed out in predetermined proportions, thoroughly mixed, and then calcined. This calcination is performed at about 700°C to 850°C. If the pre-calcination temperature is low, the sintered density will decrease, and if the pre-calcination temperature is high, the sintered density will decrease and the insulation resistance will decrease. Next, the calcined product is pulverized to produce raw material powder. Average particle size is 0.5-2μm
The degree is preferable; if it is too large, pores will increase in the sintered body, and if it is too small, moldability will deteriorate.

A slurry of such ceramic raw material powder is formed.

The slurry is produced by adding raw material powder to commonly used binders such as polyvinyl alcohol, polyvinyl butyral, methyl cell O-Z, acrylic oxygen-based binders, and solvents such as alcohol, toluene, and acetone. Next, a green sheet is entirely formed using this slurry. The usual doctor blade method may be used.

A conductive paste is printed in a predetermined pattern on the green sheet thus obtained.
Form an electrode layer. In the present invention, a paste using A#-Pd alloy powder as the conductive powder is used as the conductive paste.

When fully manufacturing a multilayer ceramic element, a predetermined number of green sheets with internal electrode layers formed thereon as described above are pressed together in a tank and then fired. Reliability is significantly improved compared to the case of using a conductive paste in which A, 9 powder, and Pdt9 are mixed separately.

In the conventional paste that mixes Ag powder and Pd powder, the Ag powder starts to melt first, so in areas where there is a lot of localized A9, there is a risk that AJF will diffuse along the grain boundaries of the ceramic and cause short circuits. However, by using the Ag-Pd alloy, there is no local uneven distribution of AII, and the possibility of short circuits etc. is extremely reduced.

In addition, Pd powder once turns into palladium oxide at 400 to 600°C, and the abnormal volume change that occurs at that time could cause cracking, delamination, etc. However, by using 1-alloyed powder, such problems can be avoided. Fear disappears.

Also in AN-Pd alloy, it is effective to suppress oxidation of Pd, and it is desirable to add Au. AN
- By using Pd-Au alloy powder, oxidation of fiPd is suppressed and the above-mentioned cracks are avoided.

Delamination can be further suppressed.

The reliability during the manufacturing of multilayer ceramic elements has been described above, but when using the Al-Pd alloy, the speed of AI microscopy is slower than when using mixed powder, resulting in short circuits and torsions. The risk of such occurrences is extremely reduced. This effect is due to Pb in the ceramic being P
This is particularly noticeable when the weight is 30wt or more in terms of bO.

The conductive paste contains, in addition to the conductive powder, an organic solvent such as kerosene or terpineol, a binder such as ethyl cellulose, a dioctyl phthalate plasticizer, and the like.

These are similar to ordinary conductor pastes. At this time, the average particle size of the conductor powder, that is, A, 9-Pd alloy, is 0.1
It is preferable to set it to about 2.0 μm. If it is less than 0.1 μm, it is difficult to make it into a paste, and even if it is formed into a thin film, the thickness of the film is so thin that it tends to cause capacity loss. Also 2.0μ
This is because if mt' is exceeded, it becomes difficult to uniformly form the electrode layer.

Note that the proportion of AJ9 in the Al1-Pd alloy conductor powder can be appropriately set according to the sintering temperature of the ceramic.

Considering cost and firing temperature, practical soil is 50-95wte.
It's a good degree. Also, as mentioned above (A u f flow Ag
-Pd-Au alloy can further improve reliability, but the amount added is limited to about 10 wt. Although the effect can be achieved by adding a small amount,
The effect becomes remarkable from 1wt%.

Moreover, it is preferable that the integral firing after lamination is performed at about 800 to 1300°C. This is because if the resistivity of the electrode layer is less than 800°C, it is difficult to make it sufficiently small, and if it exceeds 1300'Ct-%, a reaction between the electrode and the ceramic will occur.

An external electrode is applied as a flue to produce a single-curve ceramic element, but the inside is made of AJ-Pd alloy, Ap
By using a conductive paste using a -Pd-Au alloy as a conductor powder, there is no breakage during manufacturing or use of the device, which greatly contributes to improved reliability.

[Implementation sequence of the invention]

The present invention will be explained in detail below.

(P ba9sBao, os) ((Zn1/aNb2
/a) o, s (MJ't/3N b 2/3 ) a, s
]03 All ingredients were mixed to obtain a composition of 03.

Calcinate and ball mill pulverize to obtain ceramic raw material powder.

A slurry was created by dispersing it in ethyl cellosolve and adding a binder, and then a ceramic green sheet with a thickness of 35 μm was created on a polyester film using a doctor plaid. The conductive paste for internal electrodes is kerosene,
Terpineol, dioctyl phthalate dissolved in ethyl cellulose t-1 in an organic solvent with an average particle size of 0.2 μm.
AJ-20Pd metal powder was added and sufficiently kneaded using three rolls to prepare the product. Similarly, soAg-15Pd-5Au
I also created Alloy Nohest. For comparison, a mixed powder paste containing 80 parts by weight of AI9 powder and 20 parts by weight of Pd powder was also prepared at the same time.

Figure 2 is the XM diffraction diagram of AJ-Pd alloy powder, Figure 3 is Ay
, is an X-ray diffraction diagram of a Pd mixed powder. In the case of alloys, there is one main peak, and in the case of mixed powders, there are two main peaks, which are easily distinguishable.

This conductor paste was printed in a predetermined pattern on the green sheet described above. 20 rW of sheets having such an electrode pattern were laminated and pressure bonded. Thereafter, it was cut into a predetermined shape, degreased, and fired under 1020'CX2H conditions. After sintering, AN paste was baked as the external electrode 3 to produce a multilayer ceramic capacitor in which ceramic dielectrics 1ii1 and internal electrodes 2 were alternately laminated as shown in a partial cross-sectional view in FIG.

Using this sample, first 50 pieces were taken out and the presence or absence of delamination, the number of shorts, and the number of cracks were checked, and the results shown in Table 1 were obtained. As is clear from the results in Table 1, the number of defective products in the samples of the present invention is extremely low compared to the conventional products.

Table 1: Classification of defect occurrences and yield rate Further, 50 pieces were taken out and their electrical characteristics were investigated. The results are shown in Table 2. It is clearly seen from Table 2 that the f# layer capacitor of the present invention has extremely good electrical characteristics, particularly fn withstand voltage.

Table 2: Electrical properties Further, 200 samples were taken from each sample, and the defective rate after applying soV at 85°C x lo00H and the defective rate after 100 hours at 121°C x 2 atm water vapor and 5V were determined. . The results are shown in Table 3. It is clear that products using the internal electrical paste of the present invention have much better reliability than conventional products.

Wc3 table Reliability test In this example (Pb Q, 95B a Q, 05) [
(Zn l/3Nb2/3]0.5(Ml 1/3Nb
2/3) o, s] on 'Fr, indicates when used.

Other systems, such as PbTi0. Similar results were obtained with -PbZrOs system 1 and the like. Further, although the case of a WIll ceramic capacitor was shown as the ma-type ceramic element, similar results were obtained with piezoelectric type, electrostrictive type actuator, and eta element having similar structures.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a highly reliable multilayer ceramic element that is free from breakage during manufacturing and characteristic deterioration during use.

[Brief explanation of drawings]

Figure 1 is a schematic partial cross-sectional perspective view of a multilayer ceramic capacitor, and Figure 2 is AI! -X1-ray diffraction diagram of Pd alloy powder %3
Figure A, 9. xuA diffraction pattern of Pd mixture. Representative Patent Attorney Kensuke Chika (and 1 other person) No. 1
Figure □2θ

Claims (6)

[Claims] (1) When manufacturing a multilayer ceramic element in which dielectric layers and electrode layers made of ceramic with a perovskite structure containing lead as a constituent element are alternately laminated, when the electrode layers are formed, silver-palladium alloy or silver ·palladium·
A method for manufacturing a multilayer ceramic element, characterized by using a conductive paste using a gold alloy as a conductor powder. (2) The method for manufacturing a multilayer ceramic element according to claim 1, wherein the ceramic contains 30% by weight or more of lead in terms of PbO. (3) The average particle size of the conductor powder in the conductive paste is 0.1
2. The method of manufacturing a multilayer ceramic element according to claim 1, wherein the thickness is 2.0 μm. (4) The method for manufacturing a multilayer ceramic element according to claim 1, wherein the content of silver in the conductor powder is 50 to 95% by weight. (5) The method for manufacturing a multilayer ceramic element according to claim 1, wherein the content of gold in the conductor powder is 10% by weight or less. (6) The method for manufacturing a multilayer ceramic element according to claim 5, wherein the content of gold in the conductor powder is 1% by weight or more.