Copper Conductive Paste for Thin MLCC Electrode Coverage
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in achieving high coverage of thin inner electrodes, which limits capacitance, despite the addition of common materials to align the sintering temperatures of conductive metal particles with dielectric layers.
Innovation Solution
A conductive paste comprising copper and ABO3 type ceramic powder with a specified ionic radius ratio is used to form inner electrodes, ensuring high coverage even when formed as thin layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of inner electrodes is reduced to increase capacitance, then the capacitance increases, but the coverage of inner electrodes decreases
Solution Approach 1:
The invention changes the chemical composition parameters of the conductive paste by adding specific ceramic materials (BaTiO3, SrTiO3, CaZrO3) to modify the sintering behavior. This compositional parameter change enables thin-layer electrodes to achieve high coverage by controlling the sintering process to prevent excessive shrinkage that would otherwise reduce coverage.
Solution Approach 2:
The invention creates a composite conductive paste material combining conductive metal particles with specific ceramic materials (BaTiO3, SrTiO3, CaZrO3). This composite formulation allows the paste to maintain both the conductivity needed for electrode function and the sintering characteristics required to achieve high coverage in thin layers, resolving the contradiction between thickness reduction and coverage maintenance.
2Manufacturing precision
If the sintering temperature of conductive metal particles is increased to improve coverage, then the coverage increases, but the temperature difference with dielectric layer sintering increases
Solution Approach 1:
The invention modifies the sintering temperature parameters by introducing ceramic materials with specific thermal properties. These ceramics act as fluxes that lower the sintering temperature of the conductive paste, allowing it to sinter at temperatures closer to the dielectric layer sintering temperature while still achieving high coverage through controlled shrinkage behavior.
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 conductive paste maintains high coverage of inner electrodes, thereby increasing the capacitance of multilayer ceramic capacitors.
Implementation Method 1
the sintering temperature of conductive metal particles included in conductive paste films that are to be the inner electrodes is lower than the sintering temperature of the ceramic that forms the dielectric layers, which means that the metal particles included in the inner electrodes are sintered first
Implementation Method 2
By adding a common material, it is possible to shift the onset of sintering of the metal particles included in the conductive paste films that are to be the inner electrodes toward higher temperatures
Data Source
AI summary
A conductive paste included in inner electrodes of a multilayer ceramic capacitor is fired and includes a conductive metal powder, a ceramic powder, an organic solvent, and an organic binder. The conductive metal powder includes copper, and at least a portion of the ceramic powder is a powder of at least one oxide of an ABO3 type with a specified ionic radius in which a ratio of a six-coordinate ionic radius of an A-site element in ABO3 to a six-coordinate ionic radius of copper is about 0.96 or greater and about 1.04 or less.