Dielectric compositions and methods to form the same

Details Dielectric compositions and methods to form the same Dielectric compositions and methods to form the same

2001-04-11

2004-01-06

Gupta, Yogendra N. (Department: 1751)

Compositions

Fluent dielectric

C252S572000, C252S573000, C361S321400, C361S321100, C361S321200, C361S321300, C361S311000, C361S312000

Reexamination Certificate

active

06673274

ABSTRACT:

FIELD OF INVENTION
The invention relates generally to dielectric materials and, more particularly, to barium titanate-based compositions that may be used to form dielectric layers in an electronic device such as a multilayer ceramic capacitor.
BACKGROUND OF INVENTION
Barium titanate-based compositions, which include barium titanate (BaTiO
3
) and its solid solutions, may be used to form dielectric layers in electronic devices such as multilayer ceramic capacitors (MLCCs). The barium titanate-based compositions are typically produced as small particles (e.g., about 1 micron or less) which may be further processed to form a dielectric layer. MLCCs include a series of alternating dielectric and electrode layers which are stacked to form a laminate structure. Certain types of MLCCs utilize nickel-based electrodes. Nickel-based electrodes may provide cost savings over precious metal-based electrodes (e.g., Pd, Ag—Pd).
Industry standards exist to qualify the performance of MLCC devices. For example, an MLCC is required to have certain electrical and mechanical properties to achieve X7R specifications or X5R specifications. The X7R specification has a temperature stability requirement (a capacitance at −55° C. and at 125° C. that varies less than +/−15% from the capacitance at 25° C.) and a dissipation factor requirement (less than 3.5% at 1.0 Vrms). The X5R specification has a temperature stability requirement (a capacitance at −55° C. and at 85° C. that varies less than +/−15% from the capacitance at 25° C.) and a dissipation factor requirement (less than 5.0% at 1.0 Vrms).
Pure barium titanate (BaTiO
3
) undergoes several phase transformations over the temperature range of −55° C. and 125° C. which can cause a change in capacitance. For example, the tetragonal-cubic transformation that occurs near 125° C. typically causes an anomalous increase in capacitance on the order of 300-500% the value of the dielectric constant at 25° C. Thus, pure barium titanate generally cannot be used to form dielectric layers in MLCCs that satisfy the X7R or X5R specifications.
Dopants may be added to pure barium titanate in order to improve certain electrical properties of MLCCs including increasing temperature stability and decreasing dielectric loss. Typically, the dopants are metallic compounds, often in the form of oxides or hydroxides. With the addition of dopants, it is possible to form compositions which can form dielectric layers of MLCCs that satisfy the X7R or X5R requirements. However, sometimes, such compositions can have other disadvantages such as a relatively low capacitance and/or high dielectric loss which can sacrifice the performance of MLCCs which include dielectric layers formed from the compositions.
SUMMARY OF INVENTION
The invention provides dielectric compositions, methods of forming the same, and capacitors that include dielectric layers formed from the dielectric compositions.
In one aspect the invention provides a dielectric composition. The dielectric composition comprises a barium titanate-based material, a rare earth metal compound, a manganese compound, an alkaline earth metal compound, a hexavalent metal compound, and a silicate-based compound.
In another aspect, the invention provides a dielectric composition. The dielectric composition comprises barium titanate, yttrium which comprises between about 0.10% and about 2.5% of the total weight of the dielectric composition, manganese which comprises between about 0.01% and about 0.20% of the total weight of the dielectric composition, magnesium which comprises between about 0.01% and about 0.50% of the total weight of the dielectric composition, molybdenum which comprises between about 0.01% and about 0.20% of the total weight of the dielectric composition, and barium silicate which comprises between about 0.50% and about 5.0% of the total weight of the dielectric composition.
In another aspect, the invention provides a dielectric composition. The dielectric composition comprises barium titanate-based particles. The barium titanate-based particles have a coating comprising a rare earth metal compound, a manganese compound, an alkaline earth metal compound, a hexavalent metal compound, and a silicate-based compound.
In another aspect, the invention provides a capacitor. The capacitor includes at least one electrode layer and at least one dielectric layer. The dielectric layer comprises a barium titanate-based material, a rare earth metal compound, a manganese compound, an alkaline earth metal compound, a hexavalent metal compound, and a silicate-based compound.
In another aspect, the invention provides at least one electrode layer and at least one dielectric layer. The dielectric layer comprises a dielectric composition. The dielectric composition comprises the dielectric composition comprises barium titanate, ytrium, manganese, magnesium, molybdenum, and barium silicate. Yttrium comprises between about 0.10% and about 2.5% of the total weight of the dielectric composition. Manganese comprises between about 0.01% and about 0.20% of the total weight of the dielectric composition. Magnesium comprises between about 0.01% and about 0.50% of the total weight of the dielectric composition. Molybdenum comprises between about 0.01% and about 0.20% of the total weight of the dielectric composition. Barium silicate comprises between about 0.50% and about 5.0% of the total weight of the dielectric composition.
In another aspect, the invention provides a method of forming a dielectric composition. The method includes forming a coating on barium titanate-based particles. The coating comprises a rare earth metal compound, a manganese compound, an alkaline earth metal compound, a hexavalent metal compound, and a silicate-based compound.
Other advantages, novel features, and aspects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying figures, and from the claims.


REFERENCES:
patent: 3490927 (1970-01-01), Kahn et al.
patent: 3642527 (1972-02-01), Purdes et al.
patent: 3717487 (1973-02-01), Hurley et al.
patent: 3725539 (1973-04-01), Spangenberg
patent: 3754987 (1973-08-01), Purdes
patent: 4283753 (1981-08-01), Burn
patent: 4636248 (1987-01-01), Ogata et al.
patent: 4636378 (1987-01-01), Pastor et al.
patent: 4643984 (1987-02-01), Abe et al.
patent: 4755493 (1988-07-01), Takeuchi et al.
patent: 4764493 (1988-08-01), Lilley et al.
patent: 4829033 (1989-05-01), Menashi et al.
patent: 4832939 (1989-05-01), Menashi et al.
patent: 4855266 (1989-08-01), Burn
patent: 4859448 (1989-08-01), Klee et al.
patent: 4863883 (1989-09-01), Menashi et al.
patent: 4880757 (1989-11-01), Henslee et al.
patent: 4880758 (1989-11-01), Heistand, II et al.
patent: 4886654 (1989-12-01), Ohga et al.
patent: 4898843 (1990-02-01), Matushita et al.
patent: 4937213 (1990-06-01), Bernier et al.
patent: 4939108 (1990-07-01), Dean
patent: 4987107 (1991-01-01), Narumi et al.
patent: 5011804 (1991-04-01), Bergna et al.
patent: 5029042 (1991-07-01), Dean
patent: 5082810 (1992-01-01), Bergna et al.
patent: 5082811 (1992-01-01), Bruno
patent: 5084424 (1992-01-01), Abe et al.
patent: 5086021 (1992-02-01), Sasaki et al.
patent: 5087437 (1992-02-01), Bruno et al.
patent: 5096642 (1992-03-01), Shirasaki
patent: 5112433 (1992-05-01), Dawson et al.
patent: 5155072 (1992-10-01), Bruno et al.
patent: 5225960 (1993-07-01), Kishi et al.
patent: 5296426 (1994-03-01), Burn
patent: 5335139 (1994-08-01), Nomura et al.
patent: 5362472 (1994-11-01), Lauter et al.
patent: 5403797 (1995-04-01), Ohtani et al.
patent: 5445806 (1995-08-01), Kinugasa et al.
patent: 5453262 (1995-09-01), Dawson et al.
patent: 5590387 (1996-12-01), Schmidt et al.
patent: 5650367 (1997-07-01), Fujikawa et al.
patent: 5668694 (1997-09-01), Sato et al.
patent: 5690727 (1997-11-01), Azuma et al.
patent: 5734545 (1998-03-01), Sano et al.
patent: 5742473 (1998-04-01), Sano et al.
patent: 5757610 (1998-05-01), Wada et al.
patent: 5790367 (1998-08-01), Mateika et al.
patent: 5835340 (1998-

Affiliated with

Also associated with

Rating

Dielectric compositions and methods to form the same does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dielectric compositions and methods to form the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric compositions and methods to form the same will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3195843