Multilayer Ceramic Capacitor Electrodes With Local Sn Enrichment
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Solution Overview
Problem
The reduction in thickness of internal electrode layers and dielectric layers in ceramic electronic devices leads to degradation of insulation resistance and reliability due to breaking of internal electrode layers, with existing solutions insufficiently addressing the interface resistance issues between electrode layers and dielectric layers.
Innovation Solution
A multilayer ceramic device is designed with a structure where internal electrode layers made of Ni and Sn are alternately stacked with dielectric layers, featuring a discontinuity and an Sn high concentration portion on the surface of the internal electrode layers, which increases the potential barrier and reduces oxygen vacancy concentration, thereby enhancing insulation resistance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of internal electrode layers and dielectric layers is reduced to achieve downsizing and high capacity, then the capacity increases, but the insulation resistance degrades due to breaking of internal electrode layers
Solution Approach 1:
The patent applies local quality by creating an Sn high concentration portion specifically at the discontinuity of the internal electrode layer, rather than uniformly distributing Sn throughout the entire layer. This localized enrichment of Sn at the critical discontinuity region increases the potential barrier locally, preventing ion migration and maintaining insulation resistance at the most vulnerable point while keeping the overall layer thickness reduced for high capacity.
Solution Approach 2:
The patent changes the concentration parameter of Sn at the discontinuity region, creating a localized high concentration portion with Sn concentration higher than the average Sn concentration of the internal electrode layer. This parameter change (increasing Sn concentration locally) increases the potential barrier height, thereby preventing ion migration and maintaining insulation resistance despite the reduced thickness of the electrode and dielectric layers.
2Quantity of substance
If the thickness of internal electrode layers is reduced, then the capacity increases, but the interface resistance between electrode layers and dielectric layers increases
Solution Approach 1:
The patent addresses interface resistance by creating local quality variation - specifically, an Sn high concentration portion at the discontinuity of the internal electrode layer. This localized Sn enrichment modifies the interface properties at the critical discontinuity region, reducing interface resistance where it is most problematic, while maintaining overall thin layer structures for high capacity.
3Ease of manufacture
If discontinuities are formed in internal electrode layers, then the manufacturing process becomes simpler, but the electric field concentration increases and reliability degrades
Solution Approach 1:
The patent converts the harmful effect of discontinuities (which cause electric field concentration and ion migration) into a beneficial structure by intentionally creating an Sn high concentration portion at the discontinuity. The discontinuity is retained for manufacturing simplicity, but the localized Sn enrichment transforms it from a harmful defect into a controlled feature that increases potential barrier and prevents ion migration, thereby maintaining insulation resistance.
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 solution effectively improves the insulation resistance and reliability of the ceramic electronic device by increasing the potential barrier and reducing oxygen vacancy concentration near the discontinuities, addressing the degradation issues caused by electric field concentration and interface resistance.
Implementation Method 1
an Sn high concentration portion, of which an Sn concentration is higher than an average Sn concentration of the one of the internal electrode layers, is formed on a part of a surface of the at least one of the internal electrode layers, the part of the surface being exposed to the discontinuity
Data Source
AI summary
A ceramic electronic device includes a multilayer structure in which each of a plurality of dielectric layers including Ba and Ti and each of a plurality of internal electrode layers including Ni and Sn are alternately stacked. A discontinuity is formed in at least one of the plurality of internal electrode layers, the discontinuity being a break in a cross section including a stacking direction of the multilayer structure. An Sn high concentration portion, of which an Sn concentration is higher than an average Sn concentration of the one of the internal electrode layers, is formed on a part of a surface of the at least one of the internal electrode layers, the part of the surface being exposed to the discontinuity.