Multilayer ceramic chip capacitor

• US 5,668,694 A
• Filed: 10/19/1995
• Issued: 09/16/1997
• Est. Priority Date: 10/19/1994
• Status: Expired due to Term

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Sato, Akira, Nomura, Takeshi, Arashi, Tomohiro, Nakano, Yukie, Yamamatsu, Junko, Kawano, Naoki
• Primary Examiner(s): Ledynh, Bot L.
• Application Number:
  US08/545,255
• Time in Patent Office: 698 Days
• Field of Search: 361/311-313, 361/320, 361/321.1, 361/321.5, 361/322, 365/145, 365/149, 257/295, 257/306, 257/310
• US Class Current: 361/321.4
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: B32B 2311/22 Nickel or cobalt
• CPC Class Codes: C04B 2235/3205 Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
• 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 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3239 Vanadium oxides, vanadates or oxide forming salts thereof, e.g. magnesium vanadate
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• 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 glass constituents C04B2235/36
• CPC Class Codes: C04B 2235/6582 Hydrogen containing atmosphere
• CPC Class Codes: C04B 2235/6584 at an oxygen percentage below that of air
• CPC Class Codes: C04B 2235/6588 Water vapor containing atmospheres
• CPC Class Codes: C04B 2235/663 Oxidative annealing
• CPC Class Codes: C04B 2235/765 Tetragonal symmetry
• CPC Class Codes: C04B 2235/768 Perovskite structure ABO3
• CPC Class Codes: C04B 2235/785 Submicron sized grains, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2237/12 Metallic interlayers
• CPC Class Codes: C04B 2237/346 Titania or titanates
• CPC Class Codes: C04B 2237/40 : Metallic
• CPC Class Codes: C04B 2237/405 : Iron metal group, e.g. Co or Ni
• CPC Class Codes: C04B 2237/704 : of one or more of the ceramic layers or articles
• CPC Class Codes: C04B 2237/706 : of one or more of the metallic layers or articles
• CPC Class Codes: C04B 35/4682 : based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/6264 : Mixing media, e.g. organic solvents
• CPC Class Codes: C04B 35/63424 : Polyacrylates; Polymethacrylates
• CPC Class Codes: C04B 35/638 : Removal thereof
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: H01G 4/1227 : based on alkaline earth titanates

Abstract

The invention provides a multilayer ceramic chip capacitor which satisfies X7R property or a temperature response of its capacitance and shows a minimal change of capacitance with time under a DC electric field, a long accelerated life of insulation resistance (IR) and good DC bias performance and also provides a multilayer ceramic chip capacitor which is resistant to dielectric breakdown in addition to the above advantages. In a first form of the invention, dielectric layers contain BaTiO₃ as a major component and MgO, Y₂ O₃, at least one of BaO and CaO, and SiO₂ as minor components in a specific proportion. In a second form, the dielectric layers further contain MnO and at least one of V₂ O₅ and MoO₃ as minor components in a specific proportion. In the first form, the dielectric layer has a mean grain size of up to 0.45 μm, and in an X-ray diffraction chart of the dielectric layer, a diffraction line of (200) plane and a diffraction line of (002) plane at least partially overlap one another to form a wide diffraction line which has a half-value width of up to 0.35°.

Claims

1. A multilayer ceramic chip capacitor having a capacitor chip comprising alternately stacked dielectric layers and internal electrode layers, wherein

said dielectric layers comprise a dielectric layer material which comprises barium titanate, magnesium oxide, yttrium oxide, at least one selected from barium oxide and calcium oxide, silicon oxide, manganese oxide, and at least one selected from vanadium oxide and molybdenum oxide in such a proportion that there are present

MgO:

0.1 to 3 mol

Y₂ O₃ ;

more than 0 to 5 mol

BaO+CaO;

2 to 12 mol

SiO₂ ;

2 to 12 mol

MnO;

more than 0 to 0.5 mol

V₂ O₅ ;

0 to 0.3 mol

MoO₃ ;

0 to 0.3 mol

V₂ O₅ +MoO₃ ;

more than 0 mol

per 100 mol of BaTiO₃, provided that the barium titanate, magnesium oxide, yttrium oxide, barium oxide, calcium oxide, silicon oxide, manganese oxide, vanadium oxide, and molybdenum oxide are calculated as BaTiO₃, MgO, Y₂ O₃, BaO, CaO, SiO₂, MnO, V₂ O₅, and MoO₃, respectively, and wherein

said dielectric layer material comprises crystal grains having a mean grain size of up to 0.45 μ

m, and wherein

in an X-ray diffraction chart of said dielectric layer material, a diffraction line of (200) plane and a diffraction line of (002) plane overlap one another to form a wide diffraction line which has a half-value width of up to 0.35°

.

2. The multilayer ceramic chip capacitor of claim 1 wherein said crystal grains have a mean grain size of at least 0.10 μ

m and said wide diffraction line has a half-value width of at least 0.10°

.

3. The multilayer ceramic chip capacitor of claim 1 wherein a proportion of crystal grains in said dielectric material in which domain walls are observable is 35 to 85% in a section of said dielectric layers.

4. The multilayer ceramic chip capacitor of claim 1 wherein said internal electrode layers comprise a conductor selected from nickel or nickel alloy.

5. The multilayer ceramic chip capacitor of claim 4 wherein said nickel alloy comprises an alloy of nickel with at least one member of the group consisting of Mn, Cr, Co and Al.

6. The multilayer ceramic chip capacitor of claim 5 wherein said nickel alloy comprises at least 95% nickel by weight.

7. The multilayer ceramic chip capacitor of claim 1, wherein said crystal grains have a mean grain size of up to 0.35 μ

m.

8. The multilayer ceramic chip capacitor of claim 1 wherein said dielectric layer material comprises 0.5 to 2.0 mol of MgO;

0.01 to 0.4 mol of MnO;

0.1 to 5 mol of Y₂ O₃ ;

2 to 6 mol of BaO+CaO;

2 to 6 mol of SiO₂ ; and

0 to 0.25 mol of V₂ O₅ and 0 to 0.25 mol of MoO₃ wherein there is provided 0.01 to 0.3 mol of V₂ O₅ +MoO₃ per 100 mol of BaTiO₃.

9. The multilayer ceramic chip capacitor of claim 1 wherein said dielectric layer material comprises 1 to 5 mol of Y₂ O₃ per 100 mol of BaTiO₃.

10. The multilayer ceramic chip capacitor of claim 1 wherein said dielectric layer material comprises 0.05 to 0.25 mol of V₂ O₅ +MoO₃ per 100 mol of BaTiO₃.

11. The multilayer ceramic chip capacitor of claim 1 wherein said dielectric layer comprises 1.1 to 3.5 mol of Y₂ O₃ per 100 mol of BaTiO₃.