Multilayer Ceramic Capacitor Interface Layer for Thin Dielectric Insulation
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in maintaining high reliability and insulation resistance when dielectric layers are reduced in thickness, especially at high temperatures and high humidity, with existing solutions providing only partial improvements.
Innovation Solution
Incorporating a non-perovskite oxide interface layer with tin (Sn), barium (Ba), and titanium (Ti) within the dielectric layers, which contacts the internal electrode layers, to enhance reliability and reduce voltage levels across the ferroelectric phase, thereby improving high-temperature load life and capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of dielectric layers is reduced to make compact capacitors, then the capacitance increases, but the insulation resistance between internal electrode layers decreases
Solution Approach 1:
The patent applies local quality by creating a distinct interface layer with different composition and structure at the boundary between the dielectric layer and internal electrode layer. This interface layer, containing perovskite oxide and non-perovskite oxide phases, provides localized insulation enhancement precisely where electrical stress is highest, without requiring overall increase in dielectric layer thickness. The interface layer's unique phase composition creates a barrier that prevents charge leakage and maintains insulation resistance in thin-film capacitors.
Solution Approach 2:
The patent employs composite materials by combining perovskite oxide and non-perovskite oxide phases within the interface layer. This composite structure leverages the high permittivity of perovskite phase for capacitance while the non-perovskite phase provides insulating properties and defect passivation. The synergistic combination of these two phases in the interface layer simultaneously achieves high capacitance and maintained insulation resistance in reduced-thickness dielectric layers.
2Quantity of substance
If the thickness of dielectric layers is reduced to increase capacitance, then the capacitance increases, but the reliability at high temperature and high humidity deteriorates
Solution Approach 1:
The interface layer provides localized protection against high temperature and high humidity degradation at the critical electrode-dielectric boundary. The non-perovskite oxide phase in the interface layer acts as a barrier that prevents harmful chemical reactions and moisture penetration, while the perovskite phase maintains dielectric properties. This localized quality enhancement at the interface protects the entire capacitor structure under harsh environmental conditions.
Solution Approach 2:
The interface layer serves as an intermediary between the internal electrode layer and the bulk dielectric layer, mediating the interaction between the electrode and dielectric materials. This intermediate structure passivates interface defects, prevents direct contact between electrode and dielectric that would cause degradation, and maintains stable electrical properties under high temperature and humidity conditions.
3Reliability
If additives such as rare earth elements or magnesium are added to dielectric layers to improve insulation resistance, then the insulation resistance improves, but the device complexity increases
Solution Approach 1:
The patent changes the structural parameter of the dielectric layer by creating a phase-separated interface layer with perovskite and non-perovskite oxide phases, rather than relying on chemical composition changes through multiple additives. This parameter change in crystal structure and phase distribution achieves insulation resistance improvement without the complexity of multi-element doping, maintaining simpler material composition while achieving the desired electrical properties.
Data Source
AI summary
A multilayer ceramic capacitor includes first and second main surfaces opposite to each other in a thickness direction, first and second side surfaces opposite to each other in a width direction, first and second end surfaces opposite to each other in a longitudinal direction, an element body including dielectric layers and internal electrode layers stacked in the thickness direction, and a pair of external electrodes on the first and second end surfaces and electrically connected to the internal electrode layers, in which the dielectric layers include, as a main component, a perovskite oxide including barium and titanium, and the dielectric layers include an inner portion that is in contact with the internal electrode layer and includes an interface layer including a non-perovskite oxide including tin, barium, and titanium.