COG dielectric composition for use with nickel electrodes
View Patent ↗Multilayer ceramic chip capacitors which satisfy COG requirements and which are compatible with reducing atmosphere sintering conditions so that non-noble metals such as nickel and nickel alloys may be used for internal and external electrodes are disclosed. The capacitors exhibit desirable dielectric properties (high capacitance, low dissipation factor, high insulation resistance), excellent performance on highly accelerated life testing, and very good resistance to dielectric breakdown. The dielectric layers comprise a strontium zirconate matrix doped with other metal oxides such as TiO 2 , MgO, B 2 O 3 , CaO, MnO, Nd2O3 and Nb2O5 in various combinations.
1. A lead-free and cadmium-free dielectric material comprising a solids portion wherein the solids portion comprises, prior to firing:
no lead and no cadmium;
optionally up to about 1.3 SrTiO 3 ;
from about 70.8 wt % to about 81.7 wt % SrZrO 3 ;
optionally up to about 3.4 wt % CaZrO 3 ;
optionally up to about 7.6 wt % CaTiO 3 ;
from about 11.6 wt % to about 13.5 wt % Sr 2 Nb 2 O 7 ;
optionally up to about 7.1 wt % Nd 2 ZrO 5 ;
from about 0.27 wt % to about 0.38 wt % B 2 O 3 ;
from about 0.31 wt % to about 0.44 wt % MgO; and
optionally up to about 0.06 wt % MnO.
2. A method of forming an electronic component comprising:
applying the dielectric material of claim 1 to a substrate; and
firing the substrate at a temperature sufficient to sinter the dielectric material.
3. The method of claim 2 , wherein the firing is conducted at a temperature of from about 1200° C. to about 1350° C.
4. The method of claim 2 , wherein the firing is conducted in an atmosphere having a partial oxygen pressure of about 10 −12 atm to about 10 −8 atm.
5. A multilayer ceramic chip capacitor comprising a fired collection of:
alternately stacked layers of:
the dielectric material of claim 1 ; and
layers of an internal electrode material comprising a transition metal other than Ag, Au, Pd, or Pt.
6. The multilayer ceramic chip capacitor of claim 5 , wherein the internal electrode material comprises nickel.
7. A method of forming an electronic component comprising:
alternately applying layers of
the dielectric material of claim 1 , and
a metal-containing electrode paste onto a substrate to form a laminar stack;
firing the substrate at a temperature sufficient to sinter the dielectric material;
cutting the laminar stack to a predetermined shape;
separating the cut stack from the substrate; and
firing the stack to sinter the metal in the electrode paste and fuse the oxides in the dielectric material.
8. The method of claim 7 , wherein the layers of dielectric material, after firing, each have a thickness of about 1 microns to about 50 microns.
9. The method of claim 7 , wherein the firing is conducted at a temperature of from about 1200° C. to about 1325° C.
10. The method of claim 7 , wherein the firing is conducted in an atmosphere having a partial oxygen pressure of about 10 −12 atm to about 10 −8 atm.
11. The method of claim 7 , wherein the metal-containing electrode paste comprises nickel.
12. The composition according to claim 1 , wherein the dielectric material exhibits a dielectric constant greater than 31.
13. The electronic component formed by the method of claim 2 , wherein the sintered dielectric material exhibits a dielectric constant greater than 31.