Varistor

Patent metadata

Field	Value
Publication number	US-12148553-B2
Application number	US-202017753580-A
Country	US
Kind code	B2
Filing date	Nov 6, 2020
Priority date	Nov 8, 2019
Publication date	Nov 19, 2024
Grant date	Nov 19, 2024

Abstract

The present disclosure specifies a varistor comprising a ceramic body, which comprises a functional ceramic, and electrodes arranged inside the ceramic body. The electrodes include non-floating electrodes, which are electrically connected to external contacts of the varistor, respectively. The electrodes include at least three floating electrodes, which are electrically isolated with respect to the external contacts. At least two floating electrodes are arranged in the same layer, and each of the floating electrodes overlaps with at least two further electrodes. At least two floating electrodes overlap with one of the non-floating electrodes, respectively. A distance (D 1 ) is defined along a longitudinal axis of the ceramic body between two of the electrodes overlapping with a first floating electrodes, and a distance (D 2 ) is defined perpendicular to the longitudinal axis between the first floating electrode and one of the overlapping electrodes. The distance (D 1 ) is at least twice the distance (D 2 ).

First claim

The invention claimed is:

1. A varistor comprising:
a ceramic body comprising a functional ceramic;
electrodes arranged inside the ceramic body, the electrodes including non-floating electrodes that are electrically connected to external contacts of the varistor, respectively, the electrodes further including at least three floating electrodes that are electrically isolated with respect to the external contacts; and
wherein the at least three floating electrodes include at least two floating electrodes which are arranged in a same layer, and
wherein each of the at least three floating electrode overlaps with at least two of the electrodes including the non-floating electrodes and the at least three floating electrodes, and
wherein the at least two floating electrodes of the at least three floating electrodes overlap with one of the non-floating electrodes, and
wherein a distance (D 1 ) is defined along a longitudinal axis of the ceramic body between two of the electrodes overlapping with a first floating electrodes of the at least three floating electrodes, and a distance (D 2 ) is defined perpendicular to the longitudinal axis between the first floating electrode and one of the overlapping electrodes, and wherein the distance (D 1 ) is at least twice the distance (D 2 ), and
wherein the electrodes are arranged symmetrically, and wherein, thereby, thermoplastic tensions inside the ceramic body, which can occur during thermal manufacture processes as sintering, are reduced.

2. The varistor according to claim 1 , wherein floating electrodes of the at least three floating electrodes which overlap each other are arranged in two parallel layers along the longitudinal axis of the ceramic body.

3. The varistor according to claim 1 , wherein floating electrodes of the at least three floating electrodes are arranged in multiple parallel layers along a longitudinal axis of the ceramic body.

4. The varistor according to claim 1 , wherein the functional ceramic comprises metal oxide.

5. The varistor according to claim 4 , wherein the functional ceramic comprises grains.

6. The varistor according to claim 5 , wherein the grains have a diameter between 100 nm and 20 μm.

7. The varistor according to claim 6 , wherein at least two abutting grains are arranged in series in between adjacent electrodes.

8. The varistor according to claim 1 , wherein the distance between adjacent electrodes is between 400 nm and 20 μm.

9. The varistor according to claim 1 , wherein the electrodes arranged inside the ceramic body are flat.

10. The varistor according to claim 5 , wherein the non-floating electrodes and/or the at least three floating electrodes have a thickness between 1 and 3 μm.

11. The varistor according to claim 1 , wherein the electrodes comprise silver, palladium, copper, another metal or a combination thereof.

12. The varistor according to claim 1 , wherein the varistor is manufactured by multilayer technology.

13. The varistor according to claim 1 , wherein the height of the ceramic body measured perpendicular to the longitudinal axis is 100 μm or less.

14. The varistor according to claim 1 , wherein the overlap between at least one floating electrode and the two further electrodes is at least 5% and at most 45% of the extension of the floating electrode in direction of the longitudinal axis.

15. The varistor according to claim 1 , wherein the external contacts are shaped as caps.

16. The varistor according to claim 1 , wherein the thickness of the ceramic body is 100 μm or less, and the thickness of the electrodes is between 1 and 3 μm, a number of electrode layers is less than the ceramic body thickness divided by the electrode thickness.

17. The varistor according to claim 1 , further including metal oxide grains, the diameter of metal oxide grains is in the range of 5 μm to 20 μm.

18. The varistor according to claim 17 , wherein the metal oxide grains are selected from zinc oxide, bismuth oxide, chrome oxide or manganese oxide that show highly non-linear electrical characteristics, and wherein a mixture of the metal oxide as well as doping of the metal oxide improves the performance of the varistor.

19. The varistor according to claim 1 , wherein the ceramic body is rectangular in shape, two non-floating electrodes protrude into the ceramic body on each of two opposing ends, both non-floating electrodes overlap with different floating electrodes of the at least three floating electrodes, and the floating electrodes which overlap with the non-floating electrodes overlap again with two other floating electrodes of the at least three floating electrodes that are located in a middle region of the ceramic body and stacked upon each other.

20. The varistor according to claim 1 , wherein nine non-floating electrodes protrude into the ceramic body from the first and second opposing ends, and wherein, inside the ceramic body, multiple parallel layers of floating electrodes are arranged along the longitudinal axis from the first end to the second end.

21. A varistor comprising:
a ceramic body comprising a functional ceramic, the functional ceramic including grains;
electrodes arranged inside the ceramic body, the electrodes including non-floating electrodes that are electrically connected to external contacts of the varistor, respectively, the electrodes further including at least three floating electrodes that are electrically isolated with respect to the external contacts; and
wherein the at least three floating electrodes include at least two floating electrodes which are arranged in a same layer, and
wherein each of the at least three floating electrode overlaps with at least two of the electrodes including the non-floating electrodes and the at least three floating electrodes, and
wherein the at least two floating electrodes of the at least three floating electrodes overlap with one of the non-floating electrodes, and
wherein a distance (D 1 ) is defined along a longitudinal axis of the ceramic body between two of the electrodes overlapping with a first floating electrodes of the at least three floating electrodes, and a distance (D 2 ) is defined perpendicular to the longitudinal axis between the first floating electrode and one of the overlapping electrodes, and wherein the distance (D 1 ) is at least twice the distance (D 2 ), and
wherein at least two abutting grains are arranged in series in between adjacent electrodes.

22. A varistor comprising:
a ceramic body comprising a functional ceramic;
electrodes arranged inside the ceramic body, the electrodes including non-floating electrodes that are electrically connected to external contacts of the varistor, respectively, the electrodes further including at least three floating electrodes that are electrically isolated with respect to the external contacts; and
wherein the at least three floating electrodes include at least two floating electrodes which are arranged in a same layer, and
wherein each of the at least three floating electrode overlaps with at least two of the electrodes including the non-floating electrodes and the at least three floating electrodes, and
wherein the at least two floating electrodes of the at least three floating electrodes overlap with one of the non-floating electrodes, and
wherein a distance (D 1 ) is defined along a longitudinal axis of the ceramic body between two of the electrodes overlapping with a first floating electrodes of the at least three floating electrodes, and a distance (D 2 ) is de

Assignees

• Tdk Electronics Ag

Inventors

• Mohandas Prahlad Malpe
• Nabavi S Soran
• Hofrichter Alfred

Classifications

• H01C1/14

  Terminals or tapping points specially adapted for resistors; Arrangements of terminals or tapping points on resistors · CPC title

• H01C1/148

  the terminals embracing or surrounding the resistive element (H01C1/142 takes precedence) · CPC title

• H01C7/18

  comprising a plurality of layers stacked between terminals · CPC title

• H01C7/105

  Varistor cores (H01C7/12 takes precedence) · CPC title

• H01C7/108 Primary

  Metal oxide · CPC title