CN1281549C - Barium titanate based multilayer ceramic capacitor nanopowder for nickel electrode and production method thereof - Google Patents

Abstract

The present invention relates to a nanometer ceramic powder material and a production method for a barium titanate group multilayer ceramic capacitor with nickel inner electrodes, and particularly to a barium titanate group multilayer ceramic capacitor nanometer level dielectric material. The present invention adopts a coprecipitation method in a wet chemical method, adopts a reasonable formula, optimizes a synthesis technology, and produces calcined powder of barium titanate group from 20 to 50 nm powder perovskite phase under lower temperature, and the calcined powder is suitable for the nickel inner electrodes and has anti reducibility. The powder is sintered for 1 to 2 hours at the temperature of 1150 DEG C to 1250 DEG C in a reducing atmosphere, and then, the dielectric material is made by sintering, uses barium titanate as a main component, has high dielectric electrical property and is suitable for a Y5V multilayer ceramic capacitor with nickel inner electrodes. The room temperature dielectric constant of the dielectric ceramic reaches 9400, the dielectric loss is 1 to 3%, the electric resistivity is equal to or greater than 10<12> to 10<13> omega * cm. The present invention has simple equipment and low cost, and the made ceramic can satisfy requirements of high performance, miniaturization and base metallation development trend of MLCC.

Description

The preparation method of nickel inner electrode barium phthalate base laminated ceramic capacitor nanometer porcelain powder

Technical field

The invention belongs to the preparation of electron ceramic material, particularly a kind of non-precious metal nickel that is suitable for is made the preparation method that the anti-reduction barium phthalate base of interior electrode meets the laminated ceramic capacitor nano ceramics powder of Y5V standard.

Background technology

Barium titanate is one of most popular material in the electronic ceramics, and it is the important materials of producing laminated ceramic capacitor (MLCC), and the development of MLCC technology in recent years mainly concentrates on the high capacity of product, lowpriced metallization, aspects such as miniaturization and multifunction.Because the used interior electrode metal material of MLCC will carry out sintering to form monolithic structure simultaneously with dielectric substance, and the sintering temperature of conventional barium phthalate base MLCC material is up to more than 1300 ℃, need to use the fusing point height, difficult oxidation, metallic substance with low-resistance value is as inner electrode, for this reason, usually select precious metals pd/Ag (palladium/silver) alloy or pure Pd electrode for use, this will cause the electrode cost to account for significant proportion in the MLCC production cost constitutes, can not satisfy the MLCC miniaturization, development trend cheaply, and replace precious metal silver/palladium electrode one of important trend of MLCC development just with base metal nickel.But when in high temperature air, carrying out sintering with pottery owing to the nickel metal, nickel electrode is with oxidized inefficacy, so with MLCC in sintering process necessary the adopt reducing atmosphere of nickel as interior electrode, and conventional barium titanate ceramics are easy to generate the high temperature oxygen loss during sintering and become semi-conductor in reducing atmosphere, the forfeiture insulating property, therefore developing and being adapted to the anti-reduction of reducing atmosphere agglomerating ceramic medium material is the key point of nickel inner electrode MLCC technology.Foreign study shows, is that base-material mixes an amount of acceptor ion (Ca with the barium titanate ²⁺, Cr ³⁺, Fe ³⁺, Mn ²⁺), the barium titanate ceramics of Ba/Ti＞1 sintering in reducing atmosphere can keep certain insulativity.

In order to satisfy MLCC to high capacity, lowpriced metallization, the development trend of miniaturization, the dielectric ceramic layer that forms in stacked pressed compact must be done very thinly, and sandwich must comprise a lot of layers.But because the particle size of the used ceramic powder of solid-phase synthesis when ceramic layer is very thin, comprises ceramic particle very little between interior electrode more than 1 μ m at present, the reliability of the obvious deterioration electrical condenser of meeting has limited the reduction of thickness.So, must be by reducing the particle diameter of ceramic particle, to obtain material with high reliability and dielectric properties excellence.

One of important channel that overcomes the solid-phase synthesis shortcoming is to adopt wet chemical method, promptly by the liquid phase reaction synthetic powder.Some are arranged in recent years successively about prepare the report of barium titanate series powder body material with wet chemical method, for example: oxalate coprecipitation method, barium alkoxides, the common hydrolysis method of titanium alkoxide, H ₂O ₂Oxidation-hydrothermal treatment consists coupling method etc.Clabaugh, the oxalate coprecipitation method that W.S. (Journal of Teachers College (Natural Science Edition) Vol.12 No.1 Jan.1999) at first proposes is with TiCl ₄And BaCl ₂Mixing, is precipitation agent with oxalic acid, adopt to drip or the mode of short mix is reacted, more after filtration washing and drying etc. handle the presoma powder, at last presoma is carried out heat treated and promptly obtains product.Prepare BaTiO with this method ₃Powder has fast and conveniently, with low cost, and impurity introducing amount is few, and product meets characteristics such as high-performance electronic device use.But need strict control reaction conditions and thermal treatment process, to guarantee the quality of product.Barium alkoxides, the common hydrolysis method of titanium alkoxide are barium alkoxides, and the titanium alkoxide is hydrolysis simultaneously in solution, obtain precipitation or gel after, be dried again or calcine with preparation BaTiO ₃Powder.At document J.Am.Ceram.Soc., 1969,52 (10): human Ti (Obu) 4 and Ba (Opr) such as Mazdiyasni in 523～526 ₂Hydrolysis in organic solution generates precipitate gel, and after filtration, drying treatment promptly obtains high-purity, the superfine crystal form BaTiO of median size＜10nm ₃Powder.There are two shortcomings to be difficult to overcome with this method, the first, barium alkoxides is to CO ₂And H ₂O is very responsive, causes complicated operation, and working condition requires harsh.The second, hydrolytic process needs a large amount of alcohol or other organic solvent controls reaction speed, and the barium alkoxides price is more expensive in addition, so cost is higher during practical application.High purity titanium is used H in ammonia soln ₂O ₂Be oxidized to the superoxide of titanium, use Ba (OH) then ₂Solution (100 ℃～140 ℃) at a lower temperature reacts with it, thereby makes high pure and ultra-fine BaTiO ₃The method of powder is H ₂O ₂Oxidation-hydrothermal treatment consists coupling method.Prepare BaCO with this method ₃Powder does not need high-temperature roasting and long-time the grinding, has avoided Yin Gaowen and the powders that causes, so impurity introducing amount is few, and product size of particles is even, particle diameter less (about 55nm).But in actual applications because need the reaction under high pressure condition, so reduced its use value of producing in enormous quantities.

Summary of the invention

It is excessive to The present invention be directed to barium phthalate base powder particle, sintering temperature is too high, the problem such as height of crossing the electrode cost adopts the coprecipitation method in the wet chemical method, through rational formula, optimize synthesis technique, under lower temperature, prepare that the MLCC that is suitable for nickel inner electrode uses, have the mutually ultra-fine BaTiO of nano level uhligite of resistance to reduction ₃Powders calcined.In reducing atmosphere, can burn till Y5V ceramic condenser with this powder based on the high dielectric property of barium titanate in lower temperature.This method equipment is simple, with low cost, and the pottery of preparing can satisfy the MLCC high-performance, miniaturization, the development trend of lowpriced metallization.

The composition of nickel inner electrode barium phthalate base laminated ceramic capacitor nanometer porcelain powder, comprise barium titanate major ingredient and anti-reduction additive: two or more of calcium, magnesium, iron, zinc, manganese, cobalt, zirconium, and one or more oxide compound of yttrium and rare-earth elements of lanthanum, cerium, dysprosium, erbium, ytterbium, wherein major ingredient BaTiO ₃Shared mole number is 92%～98%, and anti-reduction additive accounts for 2%～8%.Used raw material is TiCl ₄Reach the nitrate of barium, calcium, magnesium, iron, zinc, manganese, cobalt, zirconium and yttrium and rare-earth elements of lanthanum, cerium, dysprosium, erbium, ytterbium.

The concrete processing step of preparation is as follows:

A) solid nitric acid barium is made its aqueous solution with water dissolution, concentration is 0.01～0.06g/ml; With TiCl ₄Make the aqueous solution of oxalic acid, concentration is 0.01～0.04g/ml; Will be as anti-reduction additive: two or more of calcium, magnesium, iron, zinc, manganese, cobalt, zirconium, and one or more solid nitric acid salt raw material of yttrium and rare-earth elements of lanthanum, cerium, dysprosium, erbium, ytterbium makes their aqueous solution with water dissolution, and every kind of concentration range is 0.01～0.1g/ml;

B) the above-mentioned solution for preparing is got material by stoichiometry in batches, join successively in the solution of being adjusted by ammoniacal liquor, and constantly stir, final pH value transfers to 9～10, and temperature of reaction is 10 ℃～100 ℃, and the reaction times is 1～2 hour;

C) after throw out being washed with water for several times earlier, under 100 ℃～200 ℃, dried through 3～5 hours;

D) at 800 ℃～900 ℃ following roastings superfine barium titanate original washing powder body material that can to obtain the anti-reduction particle size of uhligite phase after 1～2 hour be 20～50nm;

E) above-mentioned powders calcined is added sintering agent SiO ₂, B ₂O ₃, Li ₂O, one or both among the PbO after fully grinding, add and are pressed into the round billet sheet;

F) coat nickel electrode in round billet sheet two sides;

G) at N ₂-H ₂Under the reducing atmosphere, N ₂/ H ₂Intrinsic standoff ratio is 10～20: 1, heats up with 2～20 ℃/min speed, 1150 ℃～1250 ℃ insulations 1～2 hour, cools to 900 ℃～1000 ℃ then, carries out the weak oxide processing and makes pottery.

The preparation method of a kind of nickel inner electrode barium phthalate base laminated ceramic capacitor nano level dielectric materials that is proposed by the present invention has the following advantages:

1, the preparation process of chemical coprecipitation is carried out in the aqueous solution, need not other organic solvent, safe preparation process, and compliance with environmental protection requirements, equipment is simple in addition, and production cost is low, is easy to suitability for industrialized production.

2, barium titanate major ingredient and anti-reduction additive are all synthetic together with chemical coprecipitation method, carry out the fashionable particle size inequality that causes of secondary mixing to avoid major ingredient and additive etc., and purity is not high, problems such as equipment complexity.

3, the precursor by chemical coprecipitation production obtains by chemical reaction in solution, its particle size is minimum, Chemical Composition is evenly accurate, and activity is very big, can prepare full uhligite nano-scale 20～50nm powder mutually in lesser temps and short time.

4, by above-mentioned highly active anti-reduced nano level powder, in reducing atmosphere, in 1150～1250 ℃, sintering went out high performance nickel inner electrode pottery in 2 hours, sintering temperature and sintering time have been reduced, reduce energy consumption, reduced electrode cost and energy cost widely, can satisfy the development trend of MLCC lowpriced metallization.

5, after the ceramic high temperature sintered heat insulating, cool to 900～1000 ℃ and carry out the weak oxide processing, improved ceramic dielectric properties.

6, because precursor is to form in solution, and various constituent elements can be realized the mixing on molecule, the atomic scale level, so the powder chemical uniformity that roasting goes out is good, the grain size distribution of Low fire ceramic is also narrow, dielectric properties reliability height.

7, the grain-size of Low fire ceramic can be by sintering temperature and sintering time control, and grain-size is 1～3 μ m, and is evenly distributed, and helps the attenuate of thickness of dielectric layers, satisfies the development trend of MLCC miniaturization.

Embodiment

Table 1 is corresponding to example 1 each sample powder size (nm), roasting, sintering temperature (℃), sintering time (h), the DIELECTRIC CONSTANT of-30 ℃ of materials _{(30 ℃)},-30 ℃ of temperature coefficient of capacitance Tcc _{(30 ℃)}, the DIELECTRIC CONSTANT of 25 ℃ of materials _{(25 ℃)}, the dielectric loss DF of 25 ℃ of materials _{(25 ℃)}, the DIELECTRIC CONSTANT of+85 ℃ of materials _{(+85 ℃)},+85 ℃ of temperature coefficient of capacitance Tcc _{(+85 ℃)}, grain-size (μ m), insulation resistivity ρ (Ω .cm), voltage breakdown (kV/mm).

Embodiment: fixedly Ba/Ti=1.08 and magnesium, calcium, zirconium, yttrium, cerium content, changing manganese content is 1#:0.5%; 2#:1%; 3#:2%, with the synthetic precursor of coprecipitation method, and at 900 ℃ of roastings anti-reduction of acquisition in 2 hours Y5V type MLCC barium titanate based ceramic powder.Water-soluble nitrate of baryta, magnesium nitrate, nitrocalcite, zirconium nitrate, manganous nitrate, Yttrium trinitrate, cerous nitrate respectively, the aqueous solution that titanium tetrachloride is made nitrate such as the oxalic acid aqueous solution of titanium and barium, magnesium, calcium, zirconium, manganese, yttrium, cerium is as initial feed, and the proportioning in the synthetics is equivalent at Ba _mTi _nO ₃Get A=MgO, B=MnO, C=Y among the+α A+ β B+ γ C+ δ D+ ε E+ ζ F ₂O ₃, D=CeO ₂, E=ZrO ₂, F=CaO, α=0.02, β=(0.005～0.02), γ=0.002, δ=0.01, ε=0.08, ζ=0.0525, m=0.9975, n=0.92.Mix and stir, slowly add ammoniacal liquor simultaneously, PH regulates in 9.5, forms pale precipitation.The gained throw out is through washing drying, roasting acquisition barium titanate based ceramic powder.Powder is pressed into diameter 10mm, the base substrate of thickness 1mm under 2MPa pressure.Upper and lower surface is coated with nickel behind the body drying, sintering under hydrogeneous atmosphere, and 5 ℃/min of heat-up rate rises to 1200 ℃, is incubated 2 hours.Carry out cooling to room temperature with the furnace, Measuring Dielectric Constant between-30 ℃～+ 85 ℃, electrical properties such as dielectric loss after weak oxide is handled at 1000 ℃ then.Measuring result sees Table one.

Table 1

Sample number into spectrum	The roasting junction temperature (℃)	Powder size (nm)	Sintering temperature (℃)	Sintering time (h)	ε	Tcc (％)	ε 25℃	DF (％) 25℃	ε	Tcc (％)	Grain-size (μ m)	ρ *10 12 (Ω. cm)	Voltage breakdown (kv/m m)
														-30℃		+85℃
					1	900			～30	1200								2	3355	-64	9389	1.5	4050	-56	～3.0	6.2	10
2	900	～30	1200	2			2352	-68			7449	1.0	3142	-57	～3.0	9.6	9
					3	900			～30	1200								2	2355	-64	6642	1.5	2167	-67	～3.0	7.2	-

The anti-particle size of making through said process of reducing the dielectric materials powder of Y5V type nickel electrode barium phthalate base laminated ceramic capacitor is～30nm, can be in 1200 ℃ of temperature ranges, 2 hours sintering go out the Y5V type MLCC material of excellent performance, and 25 ℃ of specific inductivity of the room temperature of material are up to 9400; Between-82%～+ 22%, and has high insulation resistivity 10 at the velocity of variation of-30 ℃～+ 85 ℃ temperature range content temperature ¹²～10 ¹³, high-breakdown-voltage, the characteristics of stable performance.Reached reduction powder size, reduced sintering temperature, shortened sintering time, replaced precious metal silver/palladium electrode with base metal nickel, purpose such as reduce production costs has satisfied the miniaturization of Y5V type laminated ceramic capacitor, the development trend of lowpriced metallization.

Claims (1)

1, the preparation method of nickel inner electrode barium phthalate base laminated ceramic capacitor nanometer porcelain powder is characterized in that the step of preparation is:

A) solid nitric acid barium is made its aqueous solution with water dissolution, concentration is 0.01～0.06g/ml; With TiCl ₄Make the aqueous solution of oxalic acid, concentration is 0.01～0.04g/ml; Will be as anti-reduction additive: two or more of calcium, magnesium, iron, zinc, manganese, cobalt, zirconium, and one or more solid nitric acid salt raw material of yttrium and rare-earth elements of lanthanum, cerium, dysprosium, erbium, ytterbium makes their aqueous solution with water dissolution, and every kind of concentration range is 0.01～0.1g/ml;

B) the above-mentioned solution for preparing is got material by stoichiometry in batches, join successively in the solution of being adjusted by ammoniacal liquor, and constantly stir, final pH value transfers to 9～10, and temperature of reaction is 10 ℃～100 ℃, and the reaction times is 1～2 hour;

C) after throw out being washed with water for several times earlier, under 100 ℃～200 ℃, dried through 3～5 hours;

D) at 800 ℃～900 ℃ following roastings superfine barium titanate original washing powder body material that can to obtain the anti-reduction particle size of uhligite phase after 1～2 hour be 20～50nm.