JPS62235279A - Manufacture of high permittivity intergranular insulating layer ceramic - 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 "Industrial Application Field" The present invention relates to the production of a high dielectric constant internal grain boundary insulating layer ceramic suitable for making a high capacitance multilayer (ML) capacitor. , is a method for increasing capacity and reducing physical size, by stacking paired positive and negative electrodes by selectively connecting each of the two opposing poles, and connecting the ends of each pair of electrodes. When connected together, the total area of the -set of electrodes forms the effective surface of the capacitor.

The use of grain boundary barrier monolayer ceramics in the manufacture of small bulk capacitors (GBBL) has been known for some time. As early as 1960, British Application No. 849938 sintered high-purity BaTiO3 at 1450°C in hydrogen gas to produce porous and semiconductive BaTi with an average particle size of 1.

It discloses that it makes 3. This material is then oxidized in air at 650 DEG -1000 DEG C. to form an insulating oxidized internal grain boundary barrier layer approximately Ion thick. The characteristics of the capacitor formed from the insulating ceramic are effective 7A 7tt
rate k (or 0 is about 100000, loss tan δ is 5
KHz, 5 Vrms Te approx. 0.03 (Q = approx. 3
0).

l-,? Ij Substances 1 - Since the operating voltage is low and the operating voltage is low, lanterns and lanterns are used instead.
Using semiconducting strontium titanate doped with transition metals such as niobium and tungsten, zirconia,
Bismuth tungstate, lead germanate and others (
For example, it is mixed with a liquid phase barrier grain boundary material such as Japanese Patent Application No. 52-10598), or it is sintered as it is. When sintering without liquid phase, doped 5rTi
When an Ox sintered body was coated with a metal oxide and then fired in an oxidizing atmosphere, grain boundary substances were generated by diffusing from the surface (see Japanese Application No. 50-27998), and Japanese Application No. 49-129898 discloses a method for preparing sintered ceramics, which consists of SrTiO3, Nb2O5 and BeO
A disk is formed from a slurry consisting of 2 and an organic binder, and is fired at 1350 to 1480° C. in an atmosphere containing hydrogen. The insulating boundary layer is formed by coating the disk surface with old 203 and firing at 1300°C, which causes diffusion of molten oxide into the ceramic.

The dielectric constant obtained is about 3-5X104. The coefficient Q is about 10
It was 0.

Nihonyama'1n51-848 is 5rTiO3 and Nb2O
5 and C.

The grain boundary layer of 5i02, B
20x, GeO2, P205, Al10wl,
It is obtained by liquid diffusion at 1100° C. using a glass oxide selected from MgO2ZnO, Bi203 and Ti02.

Japanese application 58-97820 is 5rTi03, WO
No. 3, Ge20, A120i and 5i02 are pressure-formed and sintered at 1350-1450° C. in a 1/99 hydrogen/nitrogen atmosphere to produce a semiconductive ceramic. Then, PbO1B2
The mixture of 03 and Bi203(7) is melt-diffused at 1150-1300°C to form an insulating barrier layer. Dielectric constant (ε) approx. 100,0
00, Q factor 2oo tonal preferred characteristics are SiO
A weight ratio of 2/Al103 of approximately 1°5-5 was obtained.

The average grain size was 80-120 gts, and the boundary layer resistivity was approximately 2 x 109Ω·C11.
-10598 is Nb2O5, ↑a205, WOff
Alternatively, doped 5rTiO3 mixed with an oxide such as TiO2 and fired at about 1400° C. in a reducing atmosphere is disclosed. Dope is about 1! If Ii amount%, 10
Better resistivity than Ωφcm can be obtained. This application discloses the use of SiO2 as a sintering additive to grow particles with a particle size of 10 gm for application in multi-layer (BL) capacitors. This application also discloses that ZrO2 is
It is taught that the Q factor and resistivity can be improved by adding TiOz and sintering it. The boundary layer is PbO
, obtained by liquid diffusion of a mixture of B203 and Bi201.

Typical characteristics are ε=30,000 and Q=200.

Each of the aforementioned applications discloses relatively large particle size ceramics suitable for making multilayer capacitors. In fact, the effective dielectric constant of a barrier single-layer ceramic with an insulating layer at the grain boundaries of semiconductor particles is
c constant) corresponds to the grain size and the thickness of the insulating layer. This relationship is, for example, W of TiO2 ceramic.
, RHODES, Be1l Laboratory
s, Murra7 Hill, N, J, O? 9
4); Adv, Cera, (1983), Adv
dition, Interraces Elect
R, Ceram, (7), 228-238.

C= Kgb-D/d The true intrinsic dielectric constant of 1 layer) represents the thickness of the grain boundary insulating layer, thus 10 to 504 m in grain size,
Grain boundary layer 10'' to 1103n.

(0,1-1 lm), effective dielectric constant 104~10
5 was obtained.

However, when the particle size is about 5 to 10 l, this :A heavy material becomes unsuitable for multilayer capacitors. A grain size of about 30 mm is good for dielectrics, and efforts have therefore been made to concomitantly reduce grain size and barrier thickness.

Liquid phase of sintered germanium lead and borate (see:
Charatriza eyes on of Internal
Boundary Ia7er Capacton
s' by H,D, PVol, 1 page 242~
253.1982), the grain size was 0.5-2 m, the helier thickness was IHnm (0.1 m), the effective dielectric constant was 103, and the loss was relatively small (jan δ about 10
-2), with small temperature dependence (5-10%) (see US Pat. No. 4,158,219, US Pat. No. 4,237,084);
tanδ is the diffusion coefficient, and δ is the difference between the phase angle θ and 90° when alternating current flows through the capacitor. Ideally, there is no output loss in the capacitor, and 0 is π/2 and δ is 0. Should. Q is the reciprocal of tanδ, for example Q=1/lan
δ.

``Problems to be solved by the invention'' Conventionally, various ceramic materials, grain sizes, and thicknesses of grain boundary insulating layers have been investigated as suitable ceramics for high-capacity multilayer capacitors, but the dielectric constant and resistivity have not yet been determined. Neither of these could be said to have been sufficiently improved.

"Means for solving problems" Improved over conventional technology, improving temperature stability and Q factor (Q=
It would be desirable to obtain a ceramic with a high dielectric constant without sacrificing 1/lan δ).

The method of the invention as defined in claim 1 is a first step forward.

It was not particularly believed that the high temperature treatment in air following sintering would have a significant beneficial effect on the capacitor insulation properties. This is because under those conditions, 5rTiO
This is because it was thought that an important loss would occur in the semiconducting properties of the three particles.

The conditions that are a significant feature of the present invention will be explained below.

In the case of annealing, the sintered sample was repeatedly heated in an air-filled oven to each predetermined temperature for different times. The temperature was 800-1000'O, and the heating time was 0.5-5 hours.

When cooling in air, air replaced the reducing or inert atmosphere in the furnace used during sintering. The temperature changing atmosphere is at or below the sintering temperature, and normally the incoming air is no higher than 1100-1200C, or even lower, i.e. 1050 or too.

℃ or even lower, whereas sintering is generally 12
Effective at 00-1400°C. The cooling rate under such conditions is about 100-200°C/hr. In some cases, the anneal is performed simultaneously with the post-processing diffusion. This will be discussed later.

The metal dope, preferably doped niobium powder, used as the internal grain phase in this step is composed of 5rTi03 and Nb2O.
5 and a reducing atmosphere, e.g. 1-10% H2/
It is produced by firing in Ar or H2/N2 blanket or CO/CO2 mixed gas. Optionally, a ground mixture of Ti02, Nb205 and SrCOy is used and fired as described above. After doping, the material is ground to a particle size of about 0.5-5 pm using conventional techniques, such as a ball mill with ceramic or steel metal poles.

Other doped metals such as tungsten and lanthanum can be processed similarly.

Once the doped semiconducting 5rTiOy particles have a suitable mesh size, they are mixed with a suitable sintering liquid phase, a concentrating aid material, and fired to obtain the desired insulating boundary phase.

to allow mechanical mixing. On the other hand, they form an alkoxide that gels on contact with a metal-organic composition, usually 5rTiO3, thus forming a metal coating on the particle periphery (metaloxane coating). This is a new feature to add to the invention0
This mixing is usually more effective with subsequent impregnation. 5rTiO in a protective atmosphere (e.g. pure nitrogen or argon)
3 (particle size 0.8-5 h m) is impregnated into an organic solution of the composition to be deposited as a barrier layer. Solvents such as ethanol, propatool, butanol, acetylacetone are suitable, giving a concentration of the metal composition in the solution of about 5-20%, and this concentration is not critical and may be exceeded, the solution containing a small amount of It contains H2O and a gel-like catalyst, such as HCl or other acids that tend to form a gel phase on the particle surface (or NH4OH).
The gel layer is then dried and heated to render the gel an oxide of the insulating or precipitated metal composition. Suitable LJI #Mm, TmI-) Shiman 1
Chi4-1-4+rWF! Wzs&rl-v! In order to sufficiently oxidize the 4-machine composition, 500 to 600°C, in air, 1
~2 hours is good.

There are a large number of metal compositions suitable for making alkoxide solutions, including the metals normally used in the technology for producing sintering aids: for example, lead hexanate and germanium alkoxide, or boron alkoxide and bismuth alkoxide, or A solution containing silicon alkoxide and aluminum alkoxide is used. Impregnation with said solvent results in layers of germanium lead, bismuth boron, silicon aluminum, respectively after said drying. Combining multilayers is sometimes advantageous, for example one or more layers of silicon aluminum lead germanate. supplemented by one or more layers of 'g4! Dope 5 for taste
The aluminum silicate layer on the rTiO particles significantly impedes particle growth during sintering. This is totally beneficial and
It is unimaginable from the perspective of the prior art to report an adverse effect.

After sintering, the necessary liquid phase and doping 5r are added to provide improved control over the barrier layer thickness to create the desired internal grain boundary layer.
The alkoxide solution (sol-gel technology) used when mixing with TiO3 has the following advantages: There is the advantage that particles of conductive (or semi-conductive) powder can be kept in contact with a solution of the metal composition and produce an insulating barrier layer in one hour change. In other words, by adjusting the operating conditions, the amount of the coating material deposited in the form of a coating can be changed to change the electrical properties of the final ceramic. The effective thickness of the grain boundary barrier layer in this case is as small as 0.8-1.5 nm, of course the number of successive coating operations as well as the contact time, temperature, solution parameters (concentration, solvent, PH of gel-like material, etc.)
The thickness of the barrier layer can be increased by changing . This effective thickness is calculated in comparison to a glass slag which is left in a soaked state, and the coating (after drying treatment) is measured optically. Generally, the desired result is that the dry weight of the conductive particle powder is approximately 10-' to 1o-2 with this improvement.
Another advantage of the present invention is that during sintering, grain growth can be continuously reduced to lower the sintering temperature.

As mentioned above, the liquid phase sintering aid material is in the form of a solid powder so that it can be doped with the 5rTi03. Powdered 5rTi
03 is mixed with a certain amount of dry sintering aid, and the mixture is then pressed using a decomposable binder (preferably a volatile or easily flammable polymer such as polyvinyl alcohol or polyvinyl butyrel). Notably, the use of the liquid phase of sintering aids in the shaping of solid powders
This is not to be considered as an alternative to the use of alkoxides by the sol-gel technology. In fact, the combination of the two is advantageous and welcome. For example, the sol-gel coated 5rTi03 particles are further mixed with a supplementary powdered sintering aid before said sintering.

Compounds used in powder form as the sintering liquid phase include e.g.
PbO, GeO2, Bi20x, B3 BO3, P
203, 5rTi03. Sintering of semiconducting doped 5rTiO3 constitutes a liquid phase of the sintered composition, and this is an important improvement in terms of stability of the liquid phase as well as dielectric constant and Q factor. Desired sintering aid composition (wt
$) is as follows.

Pb078% -Ge0222%; Pb045$
-B 2035%-Bi20350%; Pb025
X-B20t 20! -GeO25% BaO1
0! -P 20520! .

When 5rTi01 is added to stabilize the liquid phase,
It is added to one of the above preferred compositions at a rate of about 5 wt$.

Semiconducting 5rTi mixed with the liquid phase generated by sol-gel
The sintering conditions for converting the 03 particles into a high dielectric constant internal grain boundary layer ceramic are as follows: the powder is first pressed into a disk or plate shape in the presence of a binder, and then sintered as usual in a nitrogen or weakly reducing atmosphere for 1000 sintering at a temperature of ~1300°C. As a result, a high dielectric constant of 106 was obtained, but 1. Although the dielectric constant was slightly lowered by the heated air treatment after the present invention, the Q factor and mechanical strength of the disk could be increased.

−11% +9 +↓ ++ −−L d
a%+--+ -nk-Ql +1. +
-, + mixed with tyral binder (approximately 1-2 g powder).

A piston is pressurized (2 to 5 tons/cffi2) to form a disk with a diameter of about 10 to 20 mm and a thickness of 1 to 3 cm. Then, electrodes were provided on the disk and the electrical characteristics were measured (capacitance, loss factor, and Q factor were measured using normal methods). In the formula used, C(picofarad=10@2F)=0.
0885 Regarding Sε/e, S is square cm and e is CW during calculation of ε or K (permittivity). The electrodes are made of Cu, Ag, and Pt sputtered using a normal sputtering device.
, Au, or screen-printed silver as a paint or paste that hardens at 150° C. or is fired with the compact. After sintering, the disc is then cooled in air or
Neal.

The post-sintering 7-neal treatment of the present invention is performed in combination with post-treatment diffusion similar to that shown in the prior art. Using these conditions, the sintered ceramic was subjected to a 7-neal treatment, and the electrical properties were improved by similarly diffusing molten substances into the ceramic body. Apply to both sides. Then, it is heated to 900 to 1000°C, and is annealed and melted and diffused into the ceramic. In some cases, liquid diffusion is combined with electrode formation. That is, a glass to oxide composition is applied with a silver paint composition and the whole is applied to the ceramic and then heated and diffused. During diffusion, the boundary barrier insulating material penetrates into the ceramic and silver is deposited on its surface, thus forming the desired electrode.

The compositions selected to achieve the above results are listed below in weight percent.

In another method, similar diffusion was performed by utilizing the vapor of one selected molten oxide. in this case,
The oxide is melted in a crucible (pt) and the disc is placed at the top of the melt (approximately 1 to 3
cm). A good composition for this method is that of (h) above (melted at 8000C) and 40/80 B
The following example provides a detailed illustration of the invention, with a composition of 20x /PbO (BP, melting at 900°C).

“Example 1” Doped semiconductive 5rTi03 powder (1) was prepared by combining 83g of pure 5rCO379 and Ti02 (particle size 0.75g).
m) 43.1 g and Nb20S (0.7 mol%)
1.01g. The mixture is 1
The mixture was heated to 100° C. for 2 hours in air (platinum crucible), then cooled, and further heated to 1480° C. for an intermediate time using IOX H2/ArAr mixed gas to obtain a reducible semiconductive material. The powder was then ground in a 2501 plastic mill for 24 hours. The mill used an 81 diameter tungsten carbide pole and used a 3:1 mixture of petroleum ether and tert-butanol as the solvent to coarsely grind the particle size to about 0.5 to 5 mm. After crushing, dehydrate to 88Ω
・It was cll.

Then 0.53 g of tetraethoxide, ethyl-2-
The semiconducting powder was completely immersed in an excess organic solution (PEG) containing 1.37 g of lead hexane (ff), 6 g of acetylacetone, 13 g of ethanol, and 10 mg of HCI (as a 0.1N ethanol solution). After 5-6 minutes, the powder was drained and dried at 90°C for 16 hours.
Further, it was heated in air to 550°C (4°C/win) for 1 hour. This process was repeated four times one after another.

The powder was then mixed with 75% petroleum ether and 25% t
, mixed with 1.5wtX polyvinyl butyral (PVB) such as a butanol solution, dry smoked, sieved through a 300gm sieve, and pressurized (3T/cm'') for 1r.
It was made into a molded body of am. Binder in air at 55 (1℃)
(0.5° C./win), removed, and left as is for 1 hour.

The molded body was sintered under the conditions shown in Table 1 below, and the measured properties are also listed below.

After sintering, the compact is coated with PT by conventional means by sputtering.
Provide a conductor and turn it on.
At R [l position, dielectric constant ε and Q factor are measured at 15KH
Furthermore, internal resistance was measured using a high impedance DC electronic ohmmeter. The results were shown to Omoteko.

Table I Samples I'-E were tested in air at different temperatures and for different times.
Neil did. The result table ■ shows that annealing lowers the dielectric constant and Q
This indicates that the coefficient will be increased.

Table ■ Electron microscopy showed that the particle size of this sample was 2 μm. The boundary barrier layer varies from 1 to lh layer.

"Example 2" The following components: SrCO3923, 78g (8,2g 1 mol), TiO2500g (8,28 mol) and Nb20
511.72 g (0.044 mol, doping ratio 0.7 mol 2) were ground in a 1 kg ZrO2 pole of a zirconia mill. The grinding liquid is water.The ground mass is dried in the air, and then dried in the air in an aluminum crucible for 11 hours.
Heated at 00°C for 2 hours (heating rate 400°C/hr)
, the mixture for a certain period of time (2 to 4 hours) 1450 to 148
heated under 10/90 H2/N2 gas flow at 0°C;
I gave back. The rate of increase in temperature is approximately 300-420℃/h
It was set as r. The reduced product was then ground in a polyethylene mill with VC/Co balls to 0.5-5 g, m. The grinding liquid was a mixture of 75/25 petroleum ether/1-butanol.

The doped, ground strontium titanate was washed with acetone and contacted with the selected sol-gel solution for 30 minutes in a glove box.

Sono2 (7) solutions, HM9SIA and PGI, were used.

HM9SIA (HM for short) 4.16 g Si (OEt) 4 , 30 g non-butanol, 7.8 g aluminum 2-butoxide acetylacetate chelate and 1.84 g HCI (0,I
(N alcohol solution) were mixed and heated at 70°C for 30 minutes. After cooling, 3.38 H2O and 1828 Et
Added OH.

The solution was heated to 50° C. for 30 minutes and cooled.

G1 15g acetylacetone, 2.12g germanium tetraethoxide, 5.48g Pb 2-ethylhexane, 25.5g n-butane, 1.78g H
CI (as a 0,IN ethanol solution) was mixed and the solution was refluxed for 2 hours, then cooled before use.

Pulverized reduced 5rTiO3 in N2 atmosphere for the required time,
After contacting the alkoxide solution, the slurry was drained through a glass filter in a reducing atmosphere and then exposed to air for 90 minutes.
It was dried at 0°C for 16 hours. The dry powder was then heated to 550° C. (1 h) in air for concentration. During the concentration process, the remaining components were removed. If necessary, treatment in oxygen can be performed to increase the rate of oxidation. The concentrated powder was then shaped and sintered either as such or after mixing with a powdered complementary liquid phase.

Approximately 1.5 titania powder was added to form the pressurized disk.
It was mixed with polyvinyl butyl (PvB) in a proportion of % by weight. Combine the required amount of titania with 20 g of PvB solution and 120 g of PvB solution.
The slurry was made into a slurry with 1=1 g of n-butanol/acetone solution, stirred for 30 minutes, and then evaporated. Then PVB
The coated powder is passed through a sieve (a 300gm mesh sieve), and then 2 to 5 tons/min is poured into a stainless steel mold.
A disk was formed by applying pressure with c layer 2. The molded body was then heated in air at 550° C. for 1 hour (0.5-b) to remove the binder, and then sintered.

Sintering is performed using Al2O3 connected to multiple introduction gas introduction pipes.
Pure nitrogen as the multiple introduced gas, carried out in a tubular channel!
: 10/90 (V/V) H2/N2 mixed scum! -t-&hqMhqmu snow line 1771457-tM2
kLMStoj+<WIfrw+? l? It was one root and each flow meter. By properly setting the controls, the true ratio of H2 and N2 in the furnace can be reduced to approximately 0.01! ,! =5$
(7) The ratio between 11j and 0.1$H (V/V) is desirable, and the sintering temperature is between 900℃ and 1500℃.
The sintering time was varied between 1 and several hours.

Electrodes on both sides of some of the disks were formed by applying a metal paint or paste, such as Pt, Ag or Cu paste, followed by sintering. Processing data and results are listed in Table I below. The table shows whether the inventive post-treatment in air was performed or not (comparative example). This treatment was in the air cooling mode (c).

The table shows the cooling rate in O/hr.

Table ■ The results in Table ■ show that cooling in air increases the Q factor without adversely affecting the dielectric constant. The effect of using the first layer of aluminum silicate is to prevent grain growth during sintering and to provide a somewhat better combination of Q and Q factor.

Example 3 The material of Example 2 and similar process operating parameters were again used. 5rTiC coated with reduction before sintering)
The doped powder of No. 3 was mixed with powdered supplementary liquid phase and processed as follows. 78wt% PbO and 22% Ge
A mixture with O2 (denoted as PGO) was melted in an A1201 crucible at about 1000°C (glass melting temperature), and after being maintained in the molten state for a predetermined time (1 to 4 hours), it was cast in a stainless steel mold. The glass was ground to 1-5 JLm by the process described in Example 2 (Polyethylene Mill WC/GO Pole).

Then, coated S ``↑103'' and a predetermined amount of crushed PG.
Composition with O, having PVB (pre-melted>
Slurried in 20/80 V/V acetone/isopropanol solution. The slurry contains solids (PVB approx. 0
．． 5g) 30g solution was 100cc. after that,
The slurry was dried, processed and sintered as in Example 2.

The results for the sintered disk capacitors are shown in Table V below. The parameters are the same as those in Table 2, with the addition of the amount of liquid phase (PGO) (weight ff1) and the condition of post-treatment air after sintering. In some cases, annealing (A) was carried out at a temperature instead of simply cooling in air (c).

Table V Example 4 This example describes the application of a combination of annealing and diffusion treatment to a sintered ceramic of fused glass composition. The reduction-doped strontium titanate is the same as in Example 2.3, and the processing conditions for sintering it into a disk are also the same.

Approximately 0.1 g of paste was applied to the sintered disk. This paste used one from the top of the composition list given at the end of this application description. This paste consists of approximately 3g of solids, 20g of PVB and 120g of n-butanol (
Approximately 0.0% of the solution.・1g) is mixed with a small amount of solution. The disks were dried and heated to the diffusion temperature for a specified period of time.

The first set of data is shown in Table VA below. In this case the semiconducting doped 5rTiOz particles are SrCOx 1
000g! = Ti02541g and Nb20512.
69 g of the mixture was calcined Lf (1100"C 12 hours) and then reduced in H2/N2 gas at 1480"C (4 hours) as described above. This material, after being pulverized, was mixed with HM9SIA (Reference Example 2) stream side 3) and sintered as described in Table 1A. As such, a diffused phase was applied. Thereafter, an electrode was deposited by sputtering.

Table A In yet another experiment, the initial doped 5rTi03
A double coating of aluminum silicate was applied by the sol-gel process with the above-mentioned HM hot solution. In this case, no supplementary addition of sintering aid (PGO) was made. During sintering,
Less than 0.4z of hydrogen was used in the nitrogen stream. The post-diffusion treatment parameters, diffusion compositions and results are shown in Table VB below.

Table VB The third experiment was conducted as the second experiment, with HM sol-gel treatment, but no sintering aid was added. The sintering atmosphere was nitrogen plus hydrogen in an amount not exceeding 0.4z. The data are shown in Table VC.

Table VC "Example 5" Strontium titanate doped with 0.7 mol 2 of niobium as described in Example 2 was mixed with a liquid phase sintered material as in Example 3 and processed using the sol-gel technique. produced one without coating. The sintering aid composition used was as follows (wt%): PbO78% -
Ge2022% (PGO); Pb04! J-B 20
x 5$-BiOz Oz 50ICB PB O)
; Pb025X -Bz 0320% -GeOz
5%-Bi20320%-BaOIOX-P20
s 20% (Z P hBa) In some cases, 5 wt$ of 5rTi03 was added to the above composition.

The disks were pressurized as described in previous examples and fired in a nitrogen or H2/N2 atmosphere as described above. Then, the air post-treatment of the invention (c or A) was carried out under the conditions shown in the following Table 3. The nature and amount of liquid phase, other processing conditions including sintering conditions and electrical properties are shown in the table. A sample without air post-treatment is a comparative example.

Table ■ "Effects of the Invention" The manufacturing method of the present invention coats the outer periphery of doped strontium titanate particles with metal, then shapes and sinters them, and then heats them in post-processing. And since it is temperature stable,
This makes it desirable for making high dielectric constant y1 layer capacitors.

Claims (15)

[Claims] (1) In a method for manufacturing a high dielectric constant internal grain boundary insulating layer ceramic suitable for making a high capacity multilayer capacitor, which includes the following steps (a) to (e), (a) metal-doped strontium titanate is Prepare a powder of semiconductive particles with an average particle size of 0.5 to 5 μm, (b) mix the particles with a liquid sintering aid, and the sintering aid phase is heated during firing. (c) The mixture is made into a slurry with a pyrolytic organic binder, and the slurry is pressurized to make an insulator for a capacitor. (d) The molded body is placed in an inert atmosphere or SrTiO_
The three particles are fired in a gas containing an appropriate amount of hydrogen or CO that acts to have sufficient reducing power without deteriorating their semiconductive properties, and this firing sinters the compact into a concentrated ceramic insulator. ) Cooling the insulator to ambient temperature, step (e) is performed in air and cooled according to a set process, or after step (e), the ceramic body is post-annealed in air. A method for manufacturing ceramics with high dielectric constant internal grain boundary insulating layers. (2) Step (b) is carried out by sol-gel technology, i.e., the particles of doped SrTiO_3 powder are infiltrated with a solution of metal alkoxide to gel the alkoxide, which becomes a metal coating on the particles, which is further dried to form a coated powder. A method for producing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 1, wherein the ceramic is converted into a solid phase of a sintering aid by firing, and then converted into a metal oxide by compounding. (3) The high dielectric constant interior according to claim 2, wherein the alkoxide is selected from alkoxides of Pb, Ge, Bi and B, and the metal oxide phase consists of lead germanate and lead boron bismuthate, respectively. Manufacturing method of grain boundary insulating layer ceramic. (4) Step (b) is supplemented by a first coating of the doped SrTiO_3 particles with an aluminum silicon layer, the aluminum silicate being produced using a gel-like solution of aluminum alkoxide and silicon alkoxide. A method for manufacturing the high dielectric constant internal grain boundary insulating layer ceramic according to item 2. (5) Step (b) is carried out by mechanically mixing the doped SrTiO_3 particles with a sintering aid of a pulverized mineral composition,
A method for producing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 1, wherein the composition is an oxide of one selected from Pb, Ge, Bi, P, and Ba. (6) A method for producing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 5, wherein the doped SrTiO_3 contains a metal oxide that becomes a gel-like coating of alkoxide. (7) The sintered body of step (e) is placed in air at 50°C from the sintering temperature.
A method for producing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 1, wherein the ceramic is cooled to room temperature at a rate of ~250° C./hr. (8) The sintered body in step (e) is first cooled from the sintering temperature to the set temperature in a sintering atmosphere, and then cooled in air for 50 to
A method for producing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 1, wherein the ceramic is cooled at a rate of 250° C./hr. (9) Claim 8, in which the set temperature is 800 to 1100°C and the cooling rate is 150 to 200°C/hr.
A method for manufacturing the high dielectric constant internal grain boundary insulating layer ceramic described in 2. (10) The selected annealing is performed by reheating the sintered body at 800 to 1200°C for 0.5 to 5 hours in air or oxygen. Manufacturing method for layered ceramics. (11) A glass-forming composition is applied to the sintered body prior to reheating, and the composition is melted at the annealing temperature and diffused into the ceramic to reinforce the barrier boundary insulating phase. A method for producing a high dielectric constant internal grain boundary insulating layer ceramic described in . (12) The method for producing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 11, wherein the composition forming the glass is a powdered mineral slurry, and the slurry is pasted on the surface of the sintered body. . (13) The composition forming the glass is the compound Pb, GeO
_2, B_2O_3, Bi_2O_3, PbF_2, C
13. The method for producing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 12, wherein the ceramic is selected from one or more of uO and SrTiO3. (14) High dielectric constant internal grain boundaries according to claim 12, wherein the paste further comprises a powdered metal, which metal forms a ceramic film on the ceramic during diffusion and is then used as a capacitor electrode. Manufacturing method for insulating layer ceramic. (15) The reducing atmosphere in step (d) is a mixture of oxygen and a rare gas or nitrogen or a mixed gas of CO and CO_2,
A method of manufacturing a high dielectric constant internal grain boundary insulating layer ceramic according to claim 1, wherein step (d) is carried out at a temperature of about 950-1310°C.