MAGNETIC-DIELECTRIC ASSEMBLIES AND METHODS OF FABRICATION

• US 20110227678A1
• Filed: 04/15/2011
• Published: 09/22/2011
• Est. Priority Date: 10/20/2008
• Status: Active Grant

• Current Assignee: Allumax TTI LLC
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Ly, Tri M., Zheng, Jingmin, Cruickshank, David
• Granted Patent: US 8,282,763 B2
• Time in Patent Office: Days
• US Class Current: 335/296
• CPC Class Codes: H01P 1/387 Strip line circulators
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing

Abstract

A method for making a composite magnetic-dielectric disc assembly includes forming a dielectric ceramic annular cylinder, forming a magnetic ceramic rod, assembling the magnetic ceramic rod coaxially inside the dielectric ceramic cylinder, joining the magnetic ceramic rod to the dielectric ceramic cylinder using an adhesive comprising a ceramic material to form a rod-and-cylinder assembly, and slicing the rod-and-cylinder assembly to form a plurality of composite magnetic-dielectric disc-shaped assemblies. The magnetic-dielectric disc assemblies can be used as components of, for example, circulators, isolators, or similar electrical assemblies.

Claims

1. A method for fabricating a magnetic-dielectric assembly comprising acts of:

applying an adhesive to at least a portion of at least one of an interior surface of a dielectric ceramic annular cylinder and at least a portion of a surface of a magnetic ceramic rod, the adhesive comprising a ceramic material; and

assembling the magnetic ceramic rod coaxially inside the dielectric ceramic annular cylinder to form a magnetic-dielectric assembly.

2. The method of claim 1, wherein the act of applying an adhesive comprises applying an adhesive including a matrix, the matrix having a dielectric constant lower than a dielectric constant of the ceramic material.

3. The method of claim 1 wherein the act of applying an adhesive comprises applying an adhesive including a matrix, the matrix having a thermal conductivity lower than a thermal conductivity of the ceramic material.

4. The method of claim 1, wherein the ceramic material includes powdered alumina.

5. The method of claim 4, wherein the powdered alumina includes substantially spherical particles with a median diameter in a range of from about 0.1 micrometers to about 10 micrometers.

6. The method of claim 4, further comprising an act of selecting an adhesive including from about 0.4 to about 1.2 grams of powdered alumina per gram of adhesive.

7. The method of claim 4, wherein the powdered alumina has a purity of greater than about 99%.

8. The method of claim 4, wherein the adhesive further includes an epoxy matrix.

9. The method of claim 1, further comprising an act of cutting the magnetic-dielectric assembly to form at least one magnetic-dielectric disc assembly.

10. The method of claim 9, wherein the act of cutting the magnetic-dielectric assembly includes sawing the magnetic-dielectric assembly.

11. The method of claim 9, wherein the act of cutting the magnetic-dielectric assembly includes removing adhesive from a blade of a saw with the ceramic material.

12. The method of claim 9, wherein the act of cutting the magnetic-dielectric assembly includes forming at least one magnetic-dielectric disc assembly having a desired dimensional parameter.

13. The method of claim 12, wherein the desired dimensional parameter is at least one of thickness, variation in thickness, surface roughness, and circularity.

14. The method of claim 12, wherein the at least one magnetic-dielectric disc assembly varies in thickness by less than 0.025 mm after cutting and before any further processing.

15. The method of claim 9, further comprising an act of selecting an adhesive matrix and the ceramic material to provide the adhesive with a dielectric constant such that an insertion loss at a frequency of 900 MHz of a microwave isolator comprising the at least one magnetic-dielectric disc assembly is decreased by about 0.2 decibels relative to an assembly of substantially the same materials except having an adhesive free of the ceramic material.

16. The method of claim 9, further comprising an act of selecting an adhesive matrix and the ceramic material to provide the adhesive with sufficient thermal conductivity such that during cutting, the magnetic-dielectric assembly does not result in melting of the adhesive.

17. The method of claim 1, wherein the ceramic material has a thermal conductivity of at least 0.08 cal/(sec·

cm·

K).

18. A magnetic-dielectric assembly comprising:

a ferromagnetic ceramic disc coaxially secured within a dielectric ceramic ring by an adhesive that includes a powdered ceramic selected from the group consisting of alumina, titania, silica, and zirconia.

19. The magnetic-dielectric assembly of claim 18, wherein the ferromagnetic ceramic disc includes yttrium-iron-garnet and the dielectric ceramic ring includes MgO—

CaO—

ZnO—

Al₂O₃—

TiO₂.

20. The magnetic-dielectric assembly of claim 18, mounted in an electrical device coupled to a radio frequency electric circuit.

21. The magnetic-dielectric assembly of claim 20, wherein the electrical device is at least one of a circulator and an isolator.

22. An adhesive comprising between 0.4 and 1.2 grams of abrasive per gram of adhesive.

23. The adhesive of claim 22, wherein the adhesive comprises epoxy.

24. The adhesive of claim 23, wherein the adhesive is prepared by introducing abrasive into at least one of a resin and a hardener.

25. A method of joining a first ceramic component to a second ceramic component comprising:

applying an adhesive including a ceramic material to at least one of a first surface of the first ceramic component and a second surface of the second ceramic component; and

contacting the first surface of the first ceramic component with the second surface of the second ceramic component.

26. The method of claim 25, further comprising loading the adhesive with between 0.4 and 1.2 grams of the ceramic material per gram of adhesive.

27. The method of claim 25, further comprising curing the adhesive.