Copper Electrode Varistor Fabrication With Edge Passivation
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Solution Overview
Problem
Existing varistor devices are costly to fabricate due to the use of expensive noble metals for electrode materials, and there is a need for a method that can efficiently produce varistors with comparable electrical properties while reducing fabrication expenses.
Innovation Solution
A method involving a ceramic base body with a base metal electrode region, where the electrode region is formed by exposing the base body to a protective gas atmosphere at controlled temperatures, using a cheaper material like copper, and applying a passivation layer to protect against oxidation and chemical reactions, allowing for cost-effective production and maintaining electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If noble metals are used for electrode materials in varistor devices, then electrical properties are maintained, but fabrication cost increases significantly
Solution Approach 1:
The patent replaces expensive noble metals with base metals (such as copper, aluminum, or their alloys) for the electrode region. This substitution uses cheaper materials that can be effectively protected through the subsequent application of protective coatings, thereby reducing fabrication cost while maintaining functional performance.
Solution Approach 2:
The patent introduces a protective coating layer as an intermediary between the base metal electrode region and the external environment. This coating prevents oxidation and chemical reactions, protecting the base metal from degradation and ensuring stable electrical properties over time, thus enabling the use of cheaper base metals without sacrificing reliability.
2Object-affected harmful factors
If base metal electrode region is exposed to air at high temperature, then oxidation occurs, but protective gas atmosphere adds process complexity
Solution Approach 1:
The patent employs a protective gas atmosphere (such as nitrogen or other inert gases) during the high-temperature processing of the base metal electrode region. This inert environment prevents oxidation and chemical reactions of the base metal, allowing the electrode to be formed without degradation while maintaining process control.
3Reliability
If passivation layer is applied to protect base body, then chemical resistance is improved, but manufacturing steps increase
Solution Approach 1:
The patent combines the formation of the protective coating with the high-temperature processing step used to create the base metal electrode region. By applying the protective coating before or during the sintering process, the patent integrates multiple functions (electrode formation and protection) into a single processing step, thereby reducing overall manufacturing complexity.
Solution Approach 2:
The patent applies the protective coating to the base body before the high-temperature processing of the electrode region. This preliminary action ensures that the protective layer is already in place to prevent oxidation and chemical reactions during subsequent heating, simplifying the overall process by eliminating the need for separate protection steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables the fabrication of varistor devices with similar electrical properties to those using noble metals but at a lower cost, utilizing copper for the electrode region and ensuring protection against oxidation and corrosion, thus reducing production expenses and enhancing durability.
Implementation Method 1
The ceramic material or the base body may also be a material which is not yet sintered and which is being sintered during the exposure of the base body to the temperature
Implementation Method 2
The protective gas atmosphere or ambient is, expediently, necessary to prevent an oxidation of, for example, the base body during the exposure of the base body to the temperature
Implementation Method 3
the passivation protects the base body against chemical reactions and/or influences of the protective gas during the exposure of the base body to the temperature
Implementation Method 4
the temperature is a burn-in temperature for the basic material to be burned-in or mechanically connected to the base body such that the base metal electrode region is formed
Data Source
Figure 1
AI summary
A varistor device (100) is provided that comprises a ceramic base body (1). The ceramic base body (1) comprises two metal electrode regions (2) each connected to a main surface (7) of two or more main surfaces (7). The varistor device (100) further comprises an electrode comprising a base metal electrode region (2), wherein the base metal electrode region (2) is directly connected to the ceramic base body (1). A passivation (3) is directly connected to the ceramic base body (1). The passivation (3) is disposed only at an edge surface (6) of the ceramic base body (1) The edge surface (6) connects the two or more main surfaces of the ceramic base body.