CN217847574U

CN217847574U - Metal oxide varistor device

Info

Publication number: CN217847574U
Application number: CN202221286373.6U
Authority: CN
Inventors: 蔡新明; 徐铭曦
Original assignee: Dongguan Littelfuse Electronic Co Ltd
Current assignee: Dongguan Littelfuse Electronic Co Ltd
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2022-11-18
Anticipated expiration: 2032-05-25

Abstract

A Metal Oxide Varistor (MOV) device comprising a MOV chip, a first electrode disposed on a first side of the MOV chip and a second electrode disposed on a second side of the MOV chip, a first lead connected to the first electrode and a second lead connected to the second electrode, and a protective coating covering the MOV chip, the first electrode, the second electrode and portions covering the first lead and the second lead, the protective coating comprising a base layer formed from an epoxy material and a top layer formed from a silicone material.

Description

Metal oxide varistor device

Technical Field

The present disclosure relates generally to the field of voltage suppression devices, and more particularly to a metal oxide varistor device having a coating that provides enhanced isolation voltage.

Background

Metal Oxide Varistors (MOVs) are voltage dependent nonlinear devices commonly used in electronic circuits to provide transient voltage suppression. Conventional MOV devices include a metal oxide ceramic wafer ("MOV wafer") that typically has metal electrodes attached (e.g., soldered) to planar surfaces on opposite sides thereof. Conductive leads extend from the metal electrodes to facilitate electrical connection of the MOV devices within the circuit. Portions of the MOV tab, metal electrodes and conductive leads are typically covered in a conformal coating comprising a base layer of insulating silicone and a top layer of insulating varnish. While this type of coating is suitable for meeting stringent quality requirements (e.g., AEC-Q200), it generally provides low isolation voltage capability. It is desirable to provide an MOV device with a coating that provides high isolation voltage capability and meets new quality standards (e.g. GB 30981-2020).

It is with respect to these and other considerations that the present improvements may be useful.

SUMMERY OF THE UTILITY MODEL

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This disclosure is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

An exemplary embodiment of a Metal Oxide Varistor (MOV) device according to the present disclosure may include a MOV chip, a first electrode disposed on a first side of the MOV chip and a second electrode disposed on a second side of the MOV chip, a first lead connected to the first electrode and a second lead connected to the second electrode, and a protective coating covering the MOV chip, the first electrode, the second electrode, and portions covering the first lead and the second lead, the protective coating including a base layer formed of an epoxy material and a top layer formed of a silicone material.

Drawings

The accompanying drawings illustrate an exemplary method of the disclosure including a practical application of its principles as follows:

figure 1 is a front cross-sectional view illustrating a MOV device according to an exemplary embodiment of the present disclosure.

Detailed Description

As used herein, an element or operation recited in the singular and preceded with the word "a" or "an" should be understood as encompassing multiple elements or operations, unless specified otherwise. In addition, various embodiments herein have been described in the context of one or more elements or components. An element or component may comprise any structure arranged to perform certain operations. Although an embodiment may be described using a limited number of elements in a particular topology by way of example, the embodiment may include more or less elements in alternate topologies as desired for a given implementation. Note that any reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrases "in one embodiment," "in some embodiments," and "in various embodiments" in various places in the specification are not necessarily all referring to the same embodiment.

Embodiments of a Metal Oxide Varistor (MOV) device in accordance with the present disclosure will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the disclosure are shown. However, MOV devices may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will convey to those skilled in the art certain exemplary aspects of MOV devices. In the drawings, like numerals refer to like elements throughout, unless otherwise specified.

Referring to fig. 1, a front cross-sectional view of an exemplary embodiment of a Metal Oxide Varistor (MOV) device 10 (hereinafter "device 10") according to the present disclosure is shown. For convenience and clarity, terms such as "front," "back," "top," "bottom," "upper," "lower," "above," "below," and the like may be used herein to describe the relative position and orientation of various components of the device 10, each with respect to the geometry and orientation of the device 10 as shown in fig. 1. The terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.

The device 10 may include a MOV chip 11, the MOV chip 11 having a first electrode 12 and a second electrode disposed on opposite sides thereof. In fig. 1, only the first electrode 12 on the front side of the MOV chip 11 is visible, but it will be appreciated that the second electrode on the opposite rear side of the MOV chip 11 is substantially identical to the first electrode 12. The MOV sheet 11 may be formed from any MOV composition known in the art including, but not limited to, zinc oxide particles embedded in a ceramic. The first electrode 12 and the second electrode may be formed of any suitable conductive material, including but not limited to aluminum, copper clad aluminum, silver, tin, nickel, etc. The MOV tab 11 and the first and

second electrodes

12, 12 are depicted as circular in shape, but this is not critical. It is contemplated that the MOV sheet 11 and one or more of the first and

second electrodes

12, 12 may have different shapes, such as rectangular, triangular, irregular, etc., without departing from the scope of the present disclosure.

The device 10 may further include electrically conductive first and second leads 15, 16 connected to the first and second electrodes 12, respectively, for facilitating electrical connection of the device 10 within an electrical circuit. The first and second leads 15, 16 may be formed of any suitable electrically conductive material, including but not limited to aluminum, copper clad steel, copper clad aluminum, silver, tin, nickel, etc. In various non-limiting embodiments, the first and second leads 15, 16 may be electrically connected to the first and

second electrodes

12, 16 by soldering, welding, a conductive adhesive, or the like.

The device 10 may further include a multilayer protective coating 20 (hereinafter "coating 20") covering the MOV chip 11, the first and

second electrodes

12, 16 and portions of the first and second leads 15, 16. The coating 20 may include a base layer 22 in direct contact with portions of the MOV chip 11, the first and

second electrodes

12, 16 and the first and second leads 15, 16, and a top layer 24 covering the base layer 22. The base layer 22 may be formed of an epoxy material. Various types of epoxy resins familiar to those of ordinary skill in the art may be used. The top layer 24 may be formed of a silicone material. Various types of silicone familiar to those of ordinary skill in the art may be used. Both the base layer 22 and the top layer may be applied using any suitable method (e.g., dipping, spraying, etc.). The present disclosure is not limited in this regard.

Coating 20 can provide device 10 with many advantages over conventional MOV devices. For example, the coating 20 may allow the device 10 to meet stringent quality and durability requirements (e.g., AEC-Q200). In addition, the coating 20 may provide high isolation voltage capability for the device 10 to facilitate compliance with new quality standards (e.g., GB 30981-2020).

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural elements or operations, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

The scope of the present disclosure is not limited by the specific embodiments described herein. Indeed, other various embodiments and modifications of the disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Accordingly, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Further, the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose. Those of ordinary skill in the art will recognize that usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the present disclosure as described herein.

Claims

1. A metal oxide varistor device, comprising:

an MOV sheet;

a first electrode disposed on a first side of the MOV die and a second electrode disposed on a second side of the MOV die;

a first lead connected to the first electrode and a second lead connected to the second electrode; and

a protective coating covering the MOV die, the first electrode, the second electrode, and portions covering the first and second leads, the protective coating comprising:

a base layer formed of an epoxy resin material; and

a top layer formed of a silicone material.

2. The metal oxide varistor device of claim 1, wherein the base layer is in direct contact with the MOV chip, the first electrode, the second electrode, and portions of the first and second leads, and wherein the top layer covers the base layer.