Electronically tunable, low-loss ceramic materials including a tunable dielectric phase and multiple metal oxide phases

• US 8,609,017 B2
• Filed: 02/17/2007
• Issued: 12/17/2013
• Est. Priority Date: 01/24/2001
• Status: Expired due to Term

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Blackberry Limited
• Inventors: Sengupta, Louise C., Zhang, Xubai, Chiu, Luna H.
• Primary Examiner(s): Del Sole, Joseph S
• Assistant Examiner(s): KEMMERLE III, RUSSELL J
• Application Number:
  US11/707,816
• Publication Number:
  US 20070145647A1
• Time in Patent Office: 2,495 Days
• Field of Search: 264/650, 264/614, 264/617, 501137-139
• US Class Current: 264/614
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3445 Magnesium silicates, e.g. forsterite
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/768 Perovskite structure ABO3
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 35/20 rich in magnesium oxide , e.g. forsterite C04B35/195 takes precedence
• CPC Class Codes: C04B 35/4682 based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/47 based on strontium titanates

Abstract

Electronically tunable dielectric materials having favorable properties are disclosed. The electronically tunable materials include an electronically tunable dielectric phase such as barium strontium titanate in combination with at least two additional metal oxide phases. The additional metal oxide phases may include, for example, oxides of Mg, Si, Ca, Zr, Ti and Al. The electronically tunable materials may be provided in bulk, thin film and thick film forms for use in devices such as phased array antennas, tunable filters and the like. The materials are useful in many applications, including the area of radio frequency engineering and design.

Claims

1. A method of making an electronically tunable dielectric material comprising:

mixing particles of at least one electronically tunable dielectric material including barium strontium titanate and a total of from about 1 to about 80 weight percent of particles of at least two additional metal oxide materials, wherein the at least two additional metal oxide materials are selected from a group consisting of WO₃, SnTiO₄, ZrTiO₄, CaSiO₃, CaWO₄, CaZrO₃, PbO, and Bi₂O₃;

sintering the mixed particles, wherein the electronically tunable dielectric particles and the additional metal oxide particles have average particle sizes of from about 0.1 to about 5 micron, wherein the two additional metal oxide phases have a weight ratio of from about 1;

100 to about 100;

1;

forming the electronically tunable dielectric material from the sintered mixed particles;

measuring a dielectric constant, a tunability and a dielectric loss for the electronically tunable dielectric material;

adjusting an amount of only one metal oxide material of the at least two additional metal oxide materials for the mixing step;

repeating the mixing, sintering, forming, measuring and adjusting steps to change the dielectric constant of the electronically tunable dielectric material to a desired dielectric constant while maintaining the tunability and the dielectric loss of the electronically tunable dielectric material substantially the same.

2. The method of claim 1, wherein the at least one electronically tunable dielectric material particles and the at least two additional metal oxide materials particles have average particle sizes of from about 1.5 to about 2.5 micron, and wherein an insertion loss for the at least one electronically tunable dielectric material is less than 0.02 for a frequency of 10 GHz.

3. The method of claim 1, wherein the mixing particles of at least one electronically tunable dielectric material including barium strontium titanate and a total of from about 1 to about 80 weight percent of particles of at least two additional metal oxide materials is performed in a liquid medium, and wherein the at least two additional metal oxide materials comprise a total of from about 3 to about 65 weight percent.

4. The method of claim 1, wherein the forming of the at least one electronically tunable dielectric material comprises isostatic pressing.

5. The method of claim 1, wherein the at least two additional metal oxide materials comprise a total of from about 10 to about 50 weight percent.

6. The method of claim 1, wherein the at least two additional metal oxide materials have a weight ratio of from about 1:

10 to about 10;

1.

7. The method of claim 1, wherein the at least two additional metal oxide materials have a weight ratio of from about 1:

5 to about 5;

1.

8. The method of claim 1, wherein the barium strontium titanate is of the formula Ba_xSr_1-xTiO₃, where x is from about 0.15 to about 0.6.

9. The method of claim 1, wherein the mixing of the particles is in a liquid solvent, and further comprising:

grinding the mixture of the particles to desired particle sizes, and

adding a screen printing binder to provide a viscosity between 35,000 cps to 65,000 cps.

10. The method of claim 1, wherein the at least two additional metal oxide materials do not include Al, Zr and Si.

11. The method of claim 1, wherein the dielectric constant of the formed electronically tunable dielectric material is between 300 to 400 or between 800 to 1000.

12. The method of claim 11, wherein the at least two additional metal oxide materials further comprise a third metal oxide material that is an Mg-free compound.

13. The method of claim 12, wherein the Mg-free compound comprises an oxide of a metal selected from Si, Ca, Zr, Ti and Al.

14. The method of claim 12, wherein the Mg-free compound comprises a rare earth oxide.

15. The method of claim 1, further comprising mixing the formed electronically tunable dielectric material with a polymeric binder to enable screen printing.

16. The method of claim 15, wherein the mixing of the particles is in a liquid solvent.

17. The method of claim 1, wherein the mixing is performed without adding binders to the particles of the at least one electronically tunable dielectric material and the at least two additional metal oxide materials.

18. A method of making an electronically tunable dielectric material comprising:

mixing particles of at least one electronically tunable dielectric material and a total of from about 1 to about 80 weight percent of particles of at least two additional metal oxide materials, wherein the at least two additional metal oxide materials comprise CaTiO₃ and a metal oxide selected from a group consisting of WO₃, SnTiO₄, ZrTiO₄, CaSiO₃, CaWO₄, CaZrO₃, PbO, and Bi₂O₃;

sintering the mixed particles, wherein the electronically tunable dielectric particles and the additional metal oxide particles have average particle sizes of from about 0.1 to about 5 micron, wherein the two additional metal oxide phases have a weight ratio of from about 1;

100 to about 100;

1;

forming the electronically tunable dielectric material from the sintered mixed particles;

measuring a dielectric constant, a tunability and a dielectric loss for the electronically tunable dielectric material;

adjusting an amount of only one metal oxide material of the at least two additional metal oxide materials for the mixing step;

repeating the mixing, sintering, forming, measuring and adjusting steps to change the dielectric constant of the electronically tunable dielectric material to a desired dielectric constant while maintaining the tunability and the dielectric loss of the electronically tunable dielectric material substantially the same.

19. The method of claim 18, wherein the at least one electronically tunable dielectric material is barium strontium titanate, wherein the electronically tunable dielectric particles and the additional metal oxide particles have average particle sizes of from about 1.5 to about 2.5 micron, wherein the forming of the electronically tunable dielectric material comprises one of uniaxially pressing or isostatic pressing, and wherein the at least two additional metal oxide materials comprise a third additional metal oxide material selected from a group consisting of SnTiO₄, ZrTiO₄, CaSiO₃, CaSnO₃, wherein the at least one electronically tunable dielectric material does not include barium strontium titanate.

20. The method of claim 18, wherein the at least two additional metal oxide materials comprise a total of from about 3 to about 65 weight percent of the material, and wherein the at least one electronically tunable dielectric material does not include barium strontium titanate.

21. The method of claim 18, wherein the at least two additional metal oxide materials comprise a total of from about 5 to about 60 weight percent of the material.

22. The method of claim 18, wherein the at least two additional metal oxide materials comprise a total of from about 10 to about 50 weight percent of the material.

23. A method of making an electronically tunable dielectric material comprising:

mixing particles of at least one electronically tunable dielectric material including barium strontium titanate with particles of at least two additional metal oxide materials having a total of from 1 to 80 weight percent, wherein the at least two additional metal oxide materials comprise CaTiO₃ and a metal oxide selected from a group consisting of SnTiO₄, ZrTiO₄, CaSiO₃, and CaZrO₃;

sintering the mixed particles, wherein the electronically tunable dielectric particles and the at least two additional metal oxide particles have average particle sizes of from about 0.1 to about 5 micron, wherein the two additional metal oxide phases have a weight ratio of from about 1;

100 to about 100;

1;

forming the electronically tunable dielectric material from the sintered mixed particles;

measuring a dielectric constant, a tunability and a dielectric loss for the electronically tunable dielectric material;

adjusting an amount of only one metal oxide material of the at least two additional metal oxide materials for the mixing step;

repeating the mixing, sintering, forming, measuring and adjusting steps to change the dielectric constant of the electronically tunable dielectric material to a desired dielectric constant while maintaining the tunability and the dielectric loss of the electronically tunable dielectric material substantially the same.

24. The method of claim 23, wherein the at least two additional metal oxide materials do not include Al, Zr and Si.

25. The method of claim 24, further comprising pressing the sintered mixed particles at a pressure between 5 kpsi and 10 kpsi using an acrylic binder of 2 percent by weight, wherein the mixing of the particles is in a liquid solvent, and further comprising:

grinding the mixture of the particles to desired particle sizes, and

adding a screen printing binder to provide a viscosity between 35,000 cps to 65,000 cps.

26. The method of claim 23, further comprising mixing the sintered mix with at least a solvent to form an ink having a viscosity between 35 kcps and 65 kcps.