LAMINATED CERAMIC CAPACITOR AND METHOD FOR MANUFACTURING LAMINATED CERAMIC CAPACITOR

• US 20130194718A1
• Filed: 03/14/2013
• Published: 08/01/2013
• Est. Priority Date: 02/14/2011
• Status: Abandoned Application

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Matsuda, Makoto
• Application Number:
  US13/804,798
• Publication Number:
  US 20130194718A1
• Time in Patent Office: Days
• US Class Current: 361/301.4
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3236 Alkaline earth titanates
• CPC Class Codes: C04B 2235/3239 Vanadium oxides, vanadates or oxide forming salts thereof, e.g. magnesium vanadate
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
• CPC Class Codes: C04B 2235/5445 submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/6025 Tape casting, e.g. with a doctor blade
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/6584 at an oxygen percentage below that of air
• CPC Class Codes: C04B 2235/785 Submicron sized grains, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/79 Non-stoichiometric products, e.g. perovskites (ABO3) with an A/B-ratio other than 1
• CPC Class Codes: C04B 2235/85 Intergranular or grain boundary phases
• CPC Class Codes: C04B 2237/346 Titania or titanates
• CPC Class Codes: C04B 35/4682 based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/62685 characterised by the order of addition of constituents or additives
• CPC Class Codes: H01G 4/1227 : based on alkaline earth titanates
• CPC Class Codes: H01G 4/30 : Stacked capacitors H01G4/33 takes precedence

Abstract

Provided is a laminated ceramic capacitor having excellent lifetime characteristics in a high-temperature loading test. It includes a laminated body including a plurality of stacked dielectric layers including crystal grain and crystal grain boundaries, and a plurality of internal electrodes and external electrodes. The laminated body contains, as its main constituent, a perovskite-type compound containing Ba and Ti and optionally Ca, and further contains a rare-earth element R, and Mn, Mg, V, and Si With respect to 100 parts by mol the Ti, the total parts by mol content (100×m) of Ba and Ca is 0.950≦m<1.000, the contents in terms of parts by mol is 0.3≦R≦2.5, 0.05≦Mn≦0.5, 0.5≦Mg≦2.0, 0.05≦V≦0.25, 0.5≦Si≦3.0, and further, the molar ratio x of Ca/(Ba+Ca) is 0≦x≦0.01, and the existence of the rare-earth element R in a position of 4 nm inner from a surface of the crystal grain is 20% or more.

Claims

1. A laminated ceramic capacitor comprising:

a laminated body comprising a plurality of stacked dielectric layers comprising a crystal grain and a crystal grain boundary, and a plurality of internal electrodes formed along the interfaces between the dielectric layers; and

a plurality of external electrodes formed on an outer surface of the laminated body and electrically connected to the internal electrodes,

wherein the laminated body has a composition which contains, as its main constituent, a perovskite-type compound containing Ba and Ti and optionally containing Ca, and further contains rare-earth element R, and Mn, Mg, V, and Si,

in terms of parts by mol with respect to 100 parts by mol of the Ti;

the total content (100×

m) of the Ba and the Ca is 0.950≦

m<

1.000,the content a of the R is 0.3≦

a≦

2.5, the content b of the Mn is 0.05≦

b≦

0.5,the content c of the Mg is 0.5≦

c≦

2.0,the content d of the V is 0.05≦

d≦

0.25, and the content e of the Si is 0.5≦

e≦

3.0, the molar ratio x of Ca/(Ba+Ca) is 0≦

x≦

0.10, and the existence of the rare-earth element R in a position of 4 nm inner from a surface of the crystal grain is 20% or more.

2. A laminated ceramic capacitor comprising according to claim 1 in which said contents and molar ratio are when the laminated body is dissolved in a solvent.

3. A laminated ceramic capacitor according to claim 1, wherein the dielectric layers comprise said composition.

4. The laminated ceramic capacitor according to claim 3, wherein the dielectric layers are 0.4 μ

m to 1.5 μ

m in thickness.

5. The laminated ceramic capacitor according to claim 4, wherein the Ca is present.

6. The laminated ceramic capacitor according to claim 4, wherein the Ca is absent.

7. The laminated ceramic capacitor according to claim 2, wherein the dielectric layers are 0.4 μ

m to 1.5 μ

m in thickness.

8. The laminated ceramic capacitor according to claim 7, wherein the Ca is present.

9. The laminated ceramic capacitor according to claim 7, wherein the Ca is absent.

10. The laminated ceramic capacitor according to claim 1, wherein the dielectric layers are 0.4 μ

m to 1.5 μ

m in thickness.

11. The laminated ceramic capacitor according to claim 10, wherein the Ca is present.

12. The laminated ceramic capacitor according to claim 11, wherein R is Dy.

13. The laminated ceramic capacitor according to claim 10, wherein the Ca is absent.

14. The laminated ceramic capacitor according to claim 13, wherein R is Dy.

15. A method for manufacturing a laminated ceramic capacitor comprising providing a mixture of a main constituent powder, a rare-earth element R, a Mn compound, a Mg compound, a V compound, and a Si compound, wherein the main constituent powder contains, as its main constituent, a perovskite-type compound containing Ba and Ti and optionally containing Ca;

and in terms of parts by mol with respect to 100 parts by mol of the Ti, the total content (100×

m) of the Ba and the Ca is 0.950≦

m<

1.000, the content a of the R is 0.3≦

a≦

2.5, the content b of the Mn is 0.05≦

b≦

0.5,the content c of the Mg is 0.5≦

c≦

2.0, the content d of the V is 0.05≦

d≦

0.25, and the content e of the Si is 0.5≦

e≦

3.0, the molar ratio x of Ca/(Ba+Ca) is 0≦

x≦

0.10;

forming a ceramic slurry with the mixture;

forming a ceramic green sheet from the ceramic slurry;

stacking a plurality of ceramic green sheets and at least two internal electrode layers at different interfaces between sheets to obtain an unfired laminated body; and

firing the unfired laminated body to obtain a laminated body with an internal electrode formed between dielectric layers,

wherein the dielectric layers include a crystal grain and a crystal grain boundary, and the existence of the rare-earth element R in a position of 4 nm inwardly from a surface of the crystal grain is 20% or more.