Metal oxide varistor

Abstract

The utility model discloses a metal oxide varistor with positioning features. A metal oxide varistor (MOV) includes an MOV chip having a first electrode and a second electrode disposed on opposite sides thereof; a first terminal connected to the first electrode and a second terminal connected to the second electrode, the first terminal having a plurality of through holes formed therethrough; and a dielectric coating covering the MOV chip, the first and second electrodes, and portions of the first and second terminals, the dielectric coating having a plurality of through-holes formed therethrough, each of the plurality of through-holes in the dielectric coating being aligned with one of the plurality of through-holes in the first terminal.

Description

Technical Field

[0001] The present disclosure generally relates to the field of circuit protection devices. More specifically, the present disclosure relates to metal oxide varistors having structural features facilitating precise positioning within a surge protector. Background Art

[0002] Metal oxide varistors (MOVs) play a crucial role in surge protection devices (SPDs) by rapidly responding to transient voltage spikes. These spikes, typically caused by lightning strikes or electrical surges, can damage sensitive electronic equipment. MOVs are semiconductors with non-linear voltage-current characteristics, meaning their resistance decreases as the voltage across them increases. In an SPD, the MOV is connected in parallel with the device to be protected. During normal operation, the MOV has a high resistance, allowing only a negligible amount of current to pass through. However, when a surge occurs, the voltage across the MOV rapidly increases, causing it to conduct heavily, thereby diverting the excess current from the protected device and dissipating the surge energy as heat. This action effectively clamps the voltage to a safe level, protecting the connected device from damage.

[0003] A typical MOV includes an MOV chip formed of zinc oxide grains combined with other metal oxides. The MOV chip has metal electrodes on its opposite sides, and conductive terminals are attached to each of the electrodes to facilitate the electrical connection of the MOV within a circuit (e.g., within an SPD). A conformal dielectric coating, typically formed of a polymer, surrounds portions of the MOV chip, electrodes, and terminals to provide insulation and protection to the MOV from environmental factors.

[0004] When a MOV is installed in an SPD, it is important to correctly position (i.e., place and orient) the MOV to ensure proper electrical connection of the MOV within the SPD. Various methods have been developed to assist in positioning the MOV during installation. One such method involves simply placing the MOV within a similarly sized / shaped slot or cavity within the SPD, whereby the sides or edges of the MOV are constrained to hold the MOV in the desired position and orientation. This method can be unreliable because the thickness of the dielectric coating on the MOV is typically non-uniform, resulting in tilting of the MOV chip and terminals after installation. Another method for assisting in positioning the MOV within the SPD involves forming a plurality of small positioning holes in the dielectric coating on at least one side of the MOV. When the MOV is installed within the SPD, corresponding retaining posts or detents can engage the positioning holes to hold the MOV in the desired position and orientation. This method is also associated with certain drawbacks. For example, when the positioning holes are formed in the dielectric coating of the MOV, it is possible that the terminals of the MOV (which are typically located near the positioning holes) may be damaged. Additionally, since the dielectric coating is typically very thin (e.g., about 0.5 mm thick), it can be difficult for the retaining posts or detents of the SPD to obtain a grip on the edge of the dielectric coating bordering the positioning holes. As a result, the MOV may be held loosely in place and may be prone to slipping out of or moving out of its desired position and orientation.

[0005] In view of the foregoing, it is desirable to provide a MOV that facilitates convenient, safe, and precise positioning when installed in an SPD. It is with respect to these and other considerations that the present improvements may be useful. Summary of the Utility Model

[0006] The Summary of the Utility Model is provided to introduce a selection of concepts that are further described below in the Detailed Description in a simplified form. The Summary of the Utility Model is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be a help in determining the scope of the claimed subject matter.

[0007] A metal oxide varistor (MOV) according to an embodiment of the present disclosure may include a MOV chip having a first electrode and a second electrode disposed on opposite sides thereof; a first terminal connected to the first electrode and a second terminal connected to the second electrode, the first terminal having a plurality of through holes formed therethrough; and a dielectric coating covering the MOV chip, the first and second electrodes, and portions of the first and second terminals, the dielectric coating having a plurality of through holes formed therethrough, wherein each of the plurality of through holes in the dielectric coating is aligned with one of the plurality of through holes in the first terminal.

[0008] A method of manufacturing a MOV according to an embodiment of the present disclosure may include providing a MOV chip having a first electrode and a second electrode disposed on opposite sides thereof; connecting a first terminal to the first electrode and a second terminal to the second electrode, the first terminal having a plurality of through-holes formed therethrough; applying a dielectric coating to the MOV chip, the first and second electrodes, and portions of the first and second terminals; and forming a plurality of through-holes in the dielectric coating, wherein each of the plurality of through-holes in the dielectric coating is aligned with one of the plurality of through-holes in the first terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] By way of example, various embodiments of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0010] Figure 1A is a perspective view of a MOV according to an embodiment of the present disclosure;

[0011] Figure 1B is a diagrammatic illustration Figure 1A of an exploded view of the MOV;

[0012] Figure 2 is a flowchart of a method of manufacturing a MOV according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0013] As used herein, an element or operation recited in the singular and beginning with the word "a" or "an" should be understood to possibly include a plurality of elements or operations, unless otherwise indicated. Additionally, various embodiments herein have been described in the context of one or more elements or components. An element or component may include any structure arranged to perform certain operations. Although embodiments may be described by way of example with a limited number of elements in a particular topology, the embodiments may include more or fewer elements in alternative topologies as desired for a given implementation. Note that any reference to "an embodiment" or "embodiments" 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 the specification do not necessarily all refer to the same embodiment.

[0014] Embodiments of a metal oxide varistor (MOV) according to the present disclosure and a method of manufacturing a metal oxide varistor will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the present disclosure are presented. However, the MOV and the manufacturing method can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will convey certain aspects of the MOV and the manufacturing method to those skilled in the art. In the drawings, like numerals always refer to like elements unless otherwise noted.

[0015] Reference Figure 1A and Figure 1B , a perspective view and an exploded view of a metal oxide varistor (MOV) 10 according to the present disclosure are shown (for clarity, the dielectric coating 22 of the MOV 10 described below is omitted from Figure 1B . For convenience and clarity, terms such as "top", "bottom", "above", "below", "beneath", "over" etc. may be used herein to describe the relative placement and orientation of the various components of the MOV 10, each component being related to the geometry and orientation of the MOV 10 as it appears in Figure 1A and Figure 1B . The terms will include the specifically recited words, their derivatives, and words of similar meaning.

[0016] Reference Figure 1B , the MOV 10 may include an MOV chip 12 having a first electrode and a second electrode 14a, 14b disposed on opposite sides thereof (the second electrode 14b is not within the view in Figure 1B but is substantially the same as the first electrode 14a). In various embodiments, the MOV chip 10 may be formed of zinc oxide grains combined with other metal oxides. The present disclosure is not limited in this regard. The first electrode and the second electrode 14a, 14b may be formed of any suitable conductive material, including but not limited to copper, copper alloy, aluminum, aluminum covered with copper, silver, tin, nickel, etc. The first electrode and the second electrode 14a, 14b may be attached to the MOV chip 12 via cold pressing, solder, conductive adhesive, etc., or may be deposited on the MOV chip via a sputter deposition process. The present disclosure is not limited in this regard. The MOV chip 12 and the first electrode and the second electrode 14a, 14b are depicted as being generally rectangular in shape, but this is not critical. It is contemplated that the MOV chip 12 and one or more of the first electrode and the second electrode 14a, 14b may have different shapes, such as circular, triangular, irregular shapes, etc., without departing from the scope of the present disclosure.

[0017] The MOV 10 may further include a first conductive terminal and a second conductive terminal 15, 16 connected to the first electrode and the second electrodes 14a, 14b. The first terminal and the second terminal 15, 16 may include (e.g., via soldering, welding, conductive adhesives, etc.) respective contact portions 15a, 16a mechanically connected to the first electrode and the second electrodes 14a, 14b, and respective lead portions 15b and 16b extending from the contact portions 15a, 16a to facilitate the electrical connection of the MOV 10 within the circuit. The contact portions 15a, 16a may be in an annular shape as Figure 1B shown, or may have any other suitable shape for providing a robust mechanical and electrical contact with the first electrode and the second electrodes 14a, 14b. In various non-limiting embodiments, the first terminal and the second terminal 15, 16 may be formed of copper, tin, silver, etc. The present disclosure is not limited in this regard.

[0018] The contact portion 15a of the first terminal 15 may have a plurality of through holes 20 formed therethrough. The through holes 20 are depicted as circular, but this is not critical. The through holes 20 may have any suitable shape, including but not limited to rectangular, triangular, irregular shapes, etc. The contact portion 15a is shown as having three through holes 20 formed therethrough, but this is not intended to be restrictive. In various embodiments, the contact portion 15a may have as few as two through holes 20 formed therethrough. In other embodiments, the contact portion 15a may have more than three through holes 20 formed therethrough. Additionally, although only the contact portion 15a of the first terminal 15 is provided with through holes 20, alternative embodiments of the present disclosure in which the contact portion 16a of the second terminal 16 is also provided with through holes 20 are conceivable.

[0019] Reference Figure 1A, the MOV 10 may also include a dielectric coating 22 that covers portions of the MOV chip 12, the first and second electrodes 14a, 14b, and the first and second terminals 15, 16. The dielectric coating 22 can protect the covered components of the MOV 10 from environmental factors and can prevent electrical short circuits between the MOV 10 and surrounding circuit components. In various embodiments, the dielectric coating 22 can be formed of a dielectric polymer or other dielectric material suitable for conformal application over the underlying components of the MOV 10. The dielectric coating 22 can have a plurality of through-holes 24 formed therein, and these through-holes 24 can be aligned with the through-holes 20 formed in the contact portion 15a of the first terminal 15 and can have the same overall size and shape (e.g., the same diameter) as the through-holes 20 formed in the contact portion 15a of the first terminal 15. In particular, the edges of the through-holes 24 in the dielectric coating 22 can be aligned with the corresponding underlying through-holes 20 in the contact portion 15a of the first terminal 15. The through-holes 24 can be formed in the dielectric coating 22 after the dielectric coating 22 is applied to the underlying components of the MOV 10, as described further below.

[0020] Each through-hole 24 in the dielectric coating 22 and its corresponding underlying through-hole 20 in the contact portion 15a of the first terminal 15 can together form a positioning hole 30 in the MOV 10. When the MOV 10 is installed within a surge protector, the positioning hole 30 can receive a corresponding retaining post or stop (e.g., extending from an internal compartment of the SPD adapted to hold the MOV 10) to fix the MOV 10 in a desired position and orientation. Each positioning hole 30 can have a depth equal to the sum of the thicknesses of the dielectric coating 22 and the contact portion 15a of the first terminal 15. In various embodiments, each positioning hole 30 can have a depth in the range of about 1 millimeter to about 2 millimeters. The present disclosure is not limited in this regard. This contrasts with prior art MOVs having positioning holes that extend only through the dielectric coating, where such positioning holes have a depth equal to only the thickness of the dielectric coating (e.g., about 0.5 millimeter). Thus, the positioning holes of the MOV 10 of the present disclosure are significantly deeper than those of prior art MOVs and thus allow the retaining posts or stops of the SPD to obtain a more secure and robust grip on the MOV 10 relative to prior art MOVs. Accordingly, relative to prior art MOVs, the MOV 10 of the present disclosure can be positioned more accurately and precisely within the SPD and is less likely to shift or slide after it is installed in the SPD.

[0021] Reference Figure 2 , a flowchart is shown illustrating an exemplary method for manufacturing the above-described MOV 10 according to the present disclosure. Now, in conjunction with Figure 1A and Figure 1BThe method is described with reference to the illustration of MOV 10 presented.

[0022] In Figure 2 In block 100 of the method shown, a MOV chip 12 can be provided and can have a first electrode and second electrodes 14a, 14b disposed on its opposite sides. The MOV chip 10 can be formed of zinc oxide grains combined with other metal oxides. The present disclosure is not limited in this regard. The first electrode and second electrodes 14a, 14b can be formed of any suitable conductive material, including but not limited to copper, copper alloy, aluminum, aluminum covered with copper, silver, tin, nickel, etc. The first electrode and second electrodes 14a, 14b can be attached to the MOV chip 12 via cold pressing, solder, conductive adhesive, etc., or can be deposited on the MOV chip via a sputtering deposition process. The present disclosure is not limited in this regard.

[0023] In block 110 of the method, conductive first and second terminals 15, 16 can be connected to the first electrode and second electrodes 14a, 14b, respectively. Specifically, the contact portions 15a, 16a of the first and second terminals 15, 16 can be mechanically connected to the first electrode and second electrodes 14a, 14b, such as via brazing, soldering, conductive adhesive, etc., where the respective lead portions 15b, 16b of the first and second terminals 15, 16 extend from the contact portions 15a, 16a. In various non-limiting embodiments, the first and second terminals 15, 16 can be formed of copper, tin, silver, etc. The present disclosure is not limited in this regard. As described above, the contact portion 15a of the first terminal 15 can have a plurality of through holes 20 formed therethrough. The through holes 20 can be formed in the contact portion 15a via cutting, drilling, punching, etching, etc. The present disclosure is not limited in this regard.

[0024] In block 120 of the method, a dielectric coating 22 can be applied to the MOV chip 12, the first and second electrodes 14a, 14b, and portions of the first and second terminals 15, 16. The lead portions 15b, 16b of the first and second terminals 15, 16 can extend outside of the dielectric coating 22 to facilitate electrical connection of the MOV 10 within a circuit. As described above, the dielectric coating 22 can be formed of a dielectric polymer or other dielectric material suitable for conformal application on the components underlying the MOV 10. The dielectric coating 22 can be applied to the underlying components using any suitable method (including but not limited to dipping, spraying, etc.). In block 130 of the method, through holes 24 can be formed in the dielectric coating 22, such as by cutting (e.g., laser cutting), drilling, etching, etc. As described above, the through holes 24 can be aligned with the underlying through holes 20 formed in the contact portion 15a of the first terminal 15 and can have the same overall dimensions and shape as the underlying through holes 20 formed in the contact portion 15a of the first terminal 15.

[0025] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood as not excluding a plurality of elements or steps, unless such exclusion is explicitly recited. In addition, a reference to "one embodiment" of the present disclosure is not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0026] Although the present disclosure refers to certain embodiments, many modifications, changes, and alterations to the described embodiments are possible without departing from the scope and field of the present disclosure as defined by the appended claims. Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but rather that it have the full scope defined by the language of the following claims and their equivalents.

Claims

1. A metal oxide varistor, characterized in that: include: a metal oxide varistor chip having a first electrode and a second electrode disposed on opposite sides thereof; a first terminal connected to the first electrode and a second terminal connected to the second electrode, the first terminal having a plurality of through holes formed therethrough; and a dielectric coating covering the metal oxide varistor chip, the first and second electrodes, and portions of the first and second terminals, the dielectric coating having a plurality of through holes formed therethrough, wherein each of the plurality of through holes in the dielectric coating is aligned with one of the plurality of through holes in the first terminal.

2. The metal oxide varistor according to claim 1, characterized in that: The first terminal includes a contact portion and a lead portion extending from the contact portion, wherein the contact portion is mechanically connected to the first electrode, and wherein the lead portion extends beyond the dielectric coating and facilitates electrical connection of the metal oxide varistor within a circuit, wherein a plurality of through holes in the first terminal are formed in the contact portion.

3. The metal oxide varistor according to claim 2, characterized in that: The contact portion of the first terminal is ring-shaped.

4. The metal oxide varistor according to claim 1, characterized in that: Each through hole in the dielectric coating and a corresponding underlying through hole in the first terminal together define a positioning hole having a depth equal to the sum of the thickness of the dielectric coating and the thickness of the first terminal.

5. The metal oxide varistor according to claim 1, characterized in that: Each through-hole in the dielectric coating has the same size and shape as a corresponding underlying through-hole in the first terminal.

6. The metal oxide varistor according to claim 1, characterized in that: Each positioning hole has a depth in the range of 1 mm to 2 mm.

7. The metal oxide varistor according to claim 1, characterized in that: The metal oxide varistor includes a total of at least three positioning holes.

8. The metal oxide varistor according to claim 1, characterized in that: Each through-hole in the dielectric coating has an edge aligned with an edge of a corresponding underlying through-hole in the first terminal.

9. The metal oxide varistor according to claim 1, characterized in that: The dielectric coating is formed from a dielectric polymer.

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