Patent Application
20250054663
The present disclosure relates generally to the field of circuit protection devices. More specifically, the present disclosure relates to a metal oxide varistor that can be produced using a low temperature process and that is resistant to thermal shock.
Metal oxide varistors (MOVs) are voltage dependent, nonlinear devices that provide transient voltage suppression in electronic circuits. A MOV has high electrical resistance when subjected to a low voltage and a low electrical resistance when subjected to a high voltage. When connected in parallel with a protected circuit component, a MOV can clamp voltage to a safe level in the event of a high transient voltage in the circuit. The MOV thus absorbs energy that could otherwise damage the protected component.
A conventional MOV chip is made from a composition of metal oxide granules embedded in a ceramic matrix. A shortcoming associated with such MOV compositions is that they must be subjected to a sintering process performed at very high temperatures to form a chip. Additionally, the ceramic matrix is brittle and is prone to cracking if subjected to thermal shock, which can occur during an abnormal overvoltage event. This can lead to excessive heating and combustion.
It would be desirable to provide a MOV chip that can be manufactured using low temperature (e.g., room temperature) processes. It would also be desirable to provide a MOV chip that is resistant to thermal shock.
It is with respect to these and other considerations that the present improvements may be useful.
This Summary is provided to introduce a selection of concepts in a simplified form further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is the summary intended as an aid in determining the scope of the claimed subject matter.
A metal oxide varistor (MOV) in accordance with an embodiment of the present disclosure includes 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, wherein the MOV chip is formed of a MOV composition comprising metal oxide granules embedded in a polyaniline-polymer matrix.
A method of manufacturing a metal oxide varistor (MOV) in accordance with an embodiment of the present disclosure includes placing a quantity of a MOV composition in a pressing die, the MOV composition including metal oxide granules mixed with a polyaniline-polymer, performing a pressing operation including operating the pressing die to compress the MOV composition into a solid MOV chip, and applying first and second electrodes to opposing first and second sides of the MOV chip, wherein the pressing operation is performed at a temperature in a range of 15 degrees Celsius to 200 degrees Celsius.
By way of example, various embodiments of the present disclosure will now be described, with reference to the accompanying drawings, wherein:
As used herein, an element or operation recited in the singular and proceeded with the word “a” or “an” are understood as possibly including plural elements or operations, except as otherwise indicated. Furthermore, 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 with a limited number of elements in a certain topology by way of example, the embodiment may include more or less elements in alternate topologies as desired for a given implementation. Note any reference to “one embodiment” or “an embodiment” means 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) and a method of manufacturing the same in accordance with the present disclosure will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the present disclosure are presented. The MOV and the method of manufacture may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will convey certain aspects of the MOV and the method of manufacture to those skilled in the art. In the drawings, like numbers refer to like elements throughout unless otherwise noted.
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The MOV 10 may further include electrically conductive first and second leads 15, 16 connected to the first and second electrodes 14a, 14b, respectively, for facilitating electrical connection of the MOV 10 within a circuit. In various non-limiting embodiments, the first and second leads 15, 16 may be formed of copper, tin, silver, etc., and may be electrically connected to the first and second electrodes 14a, 14b via soldering, welding, electrically conductive adhesive, etc. The present disclosure is not limited in this regard.
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The MOV chip 12 may be formed of a MOV composition that is adapted to resist thermal shock and that can be formed into a chip using low temperature processes as further described below. For example, the MOV composition may include metal oxide granules (e.g., zinc oxide granules) embedded in a polyaniline-polymer matrix. It has been found through testing that the polyaniline-polymer matrix of the present disclosure is far more robust and far less susceptible to cracking when subjected to abnormal overvoltage conditions relative to ceramic matrices used in conventional MOV chips. The risk of catastrophic failure (e.g., combustion) is therefore greatly mitigated relative to conventional MOV chips.
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Those of ordinary skill in the art will appreciate that the above-described MOV 10 and associated method of manufacture provide numerous advantages. For example, the above-described MOV composition 22, which includes a polyaniline-polymer matrix, is far more robust and far less susceptible to cracking when subjected to abnormal overvoltage conditions relative to ceramic matrices used in conventional MOV chips. The risk of catastrophic failure (e.g., combustion) is therefore greatly mitigated relative to conventional MOV chips. Additionally, the MOV composition 22 can be formed into a MOV chip using a pressing process performed at low temperatures, avoiding the need for high-temperature sintering processes that are typically employed to form MOV chips from conventional MOV compositions (i.e., metal oxide granules embedded in a ceramic matrix). Still further, the robustness and breakdown voltage of the MOV chip 12 of the present disclosure can be easily tuned by varying the ratio of metal oxide and polyaniline-polymer in the MOV composition 22.
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 steps, 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.
While the present disclosure makes reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claim(s). Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.
