Laminated Ceramic Capacitor with CaZrO3 Dielectric for Cu Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laminated ceramic capacitors using Cu internal electrodes face challenges in achieving low relative dielectric constant, temperature coefficient of capacitance, and longevity traits, particularly when sintered at low temperatures, due to the generation of secondary phases during the sintering process.
Innovation Solution
The use of a dielectric porcelain composition with a primary component of CaZrO3, auxiliary components including Mn, B, and Li, and controlled Mg content, where the Ca/Zr ratio in secondary phases is lower than in primary phases, and the number of secondary phases per 10-μm square is limited to suppress the formation of high Zr content secondary phases, ensuring low dielectric constant and improved longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low temperature sintering (1080°C or below) is used to enable Cu internal electrodes, then Cu can be used instead of Ni or Pd for low cost and low ESR, but secondary phases form during sintering that deteriorate longevity traits
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric porcelain by controlling the Ca/Zr ratio within 0.95-1.05 and limiting auxiliary components (Mn: 0.1-5.0 mol%, B: 0.1-5.0 mol%, Li: 0.1-5.0 mol%, Si: 0.1-5.0 mol%, Mg: 0.01-1.0 mol%) to prevent excessive secondary phase formation during low temperature sintering, thereby maintaining longevity traits while enabling Cu electrode use
Solution Approach 2:
The patent creates a composite dielectric material system combining CaZrO3 primary component with controlled auxiliary components (Mn, B, Li, Si, Mg) that work together to form a stable microstructure during sintering, where the composite composition suppresses harmful secondary phases while maintaining the benefits of low temperature processing
2Reliability
If low temperature sintering is used to maintain low relative dielectric constant and temperature coefficient of capacitance, then these electrical characteristics are improved, but the longevity traits deteriorate due to secondary phases
Solution Approach 1:
The patent precisely controls the Ca/Zr ratio within a narrow range of 0.95-1.05 and limits each auxiliary component to specific ranges (Mn: 0.1-5.0 mol%, B: 0.1-5.0 mol%, Li: 0.1-5.0 mol%, Si: 0.1-5.0 mol%, Mg: 0.01-1.0 mol%), which prevents excessive secondary phase formation and maintains both electrical characteristics and longevity traits
3Ease of manufacture
If Cu is used as internal electrode material for low cost and low ESR, then manufacturing cost and electrical performance are improved, but the dielectric must be sintered at low temperatures which causes secondary phase formation
Solution Approach 1:
The patent modifies the dielectric composition parameters to enable sintering at Cu's melting point (1080°C) or below, with Ca/Zr ratio of 0.95-1.05 and controlled auxiliary components, allowing Cu electrode use while suppressing secondary phase formation through optimized composition
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
This approach results in laminated ceramic capacitors with excellent voltage resistance and longevity traits, maintaining low relative dielectric constant and temperature coefficient of capacitance, while preventing excessive secondary phase formation, thus enhancing reliability and Q-value.
Implementation Method 1
sintered at low temperatures of 1080° C. or below
Data Source
AI summary
A laminated ceramic capacitor includes multiple dielectric layers, internal electrodes having Cu as the primary component and embedded between the dielectric layers, and external electrodes. The dielectric layers contain a primary component comprised of a CaZrO3 compound and auxiliary components that include Mn, B, Si, and Li wherein a primary phase comprised of the primary component, segregation phases containing Ca and at least one of the auxiliary components, and secondary phases containing at last Ca and Zr are formed. The ratio of Ca to Zr in the secondary phases is smaller than the ratio of Ca to Zr in the primary phase, and the number of secondary phases with a diameter of 100 nm or greater in a cross section of the dielectric layers averages 30 or less per 10 square μm.