VOLTAGE SWITCHABLE DIELECTRIC MATERIAL CONTAINING CONDUCTIVE CORE SHELLED PARTICLES

• US 20100090178A1
• Filed: 09/30/2009
• Published: 04/15/2010
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Littelfuse Incorporated
• Inventors: Saraf, Pragnya, Wu, Junjun, Kosowsky, Lex, Fleming, Robert, Ranganathan, Thangamani
• Granted Patent: US 9,208,930 B2
• Time in Patent Office: Days
• US Class Current: 252/513
• CPC Class Codes: H01B 1/20 Conductive material dispersed in non-conductive organic material organic macromolecular compounds or compositions C08
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01C 7/10 voltage responsive, i.e. varistors

Abstract

A composition of voltage switchable dielectric (VSD) material that comprises a concentration of core shelled particles that individually comprise a conductor core and a shell, the shell of each core shelled particle being (i) multilayered, and/or (ii) heterogeneous.

Claims

1. A composition of voltage switchable dielectric (VSD) material comprising:

a binder; and

one or more types of particles dispersed in the binder, the one or more types of particles including a concentration of core shelled particles that individually comprise a conductor core and a shell, wherein the shell is (i) multilayered, and/or (ii) heterogeneous.

2. The composition of claim 1, wherein the one or more types of particles are dispersed in the binder in a concentration that is at or above a percolation level of the composition.

3. The composition of claim 1, wherein the one or more types of particle constituents further comprises non-core shelled particles that are conductors or semi-conductors.

4. The composition of claim 1, wherein the one or more types of particle constituents further comprises non-core shelled particles that are nano-dimensioned particles.

5. The composition of claim 1, wherein the nano-dimensioned particles are high-aspect ratio particles.

6. The composition of claim 1, wherein the nano-dimensioned particles are organic.

7. The composition of claim 1, wherein the nano-dimensioned particles include carbon nano-tubes.

8. The composition of claim 1, wherein the nano-dimensioned particles include high-aspect ratio metal particles.

9. The composition of claim 1, wherein the one or more types of particle constituents further comprises non-core shelled particles that include Boron.

10. The composition of claim 1, wherein the one or more types of particle constituents further comprises active varistor particles.

11. The composition of claim 1, wherein the binder is formed a polymer.

12. The composition of claim 1, wherein the binder is formed a conductive polymer.

13. The composition of claim 1, wherein the shell includes a semi-conductive or resistive material.

14. The composition of claim 1, wherein the conductor core at least some of the core shelled particles each comprise of a metal particle.

15. The composition of claim 14, wherein the shell of at least some of the core shelled particles each comprises one or more kinds of oxides.

16. The composition of claim 15, wherein the at least some of the conductor core shelled particles comprise one or more kinds of oxides formed on the metal particles.

17. The composition of claim 14, wherein the shell of at least some of the core shelled particles each comprises one or more kinds of metal-oxides.

18. The composition of claim 1, wherein the shell of at least some of the core shelled particles is comprised of a layer that is formed from two or more types of material.

19. The composition of claim 1, wherein the shell of each of at least some of the core shelled particles is comprised of multiple layers, including a first layer and a second layer formed over the first layer, wherein a material of the first layer is different than a material of the second layer.

20. The composition of claim 1, wherein the shell of each of at least some of the core shelled particles is non-uniform, so as to expose the conductor core or an underlying shell.

21. The composition of claim 1, wherein the conductor core is nickel, and wherein the shell includes metal oxide.

22. A composition comprising:

a polymer binder;

multiple types of particle constituents, including a concentration of core shelled particles that individually comprise a metal core and a shell, wherein the shell is formed at least in part from a metal oxide and is (i) multilayered, and/or (ii) heterogeneous; and

wherein said composition is (i) dielectric in absence of a voltage that exceeds a characteristic voltage level, and (ii) conductive with application of a voltage that exceeds a characteristic voltage level of the composition.