MLCC with Cu Electrodes and BaTiO3 Additives
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Solution Overview
Problem
Existing multi-layer ceramic capacitors face challenges in achieving high permittivity and small size while being lead-free and sinterable at 1080°C or less, with previous solutions either compromising on permittivity or requiring high sintering temperatures.
Innovation Solution
A multi-layer ceramic capacitor design using a dielectric ceramic layer composed of a perovskite base material with specific additives and a Cu or Cu alloy internal electrode, allowing sintering at 1080°C or less while maintaining high permittivity and X7R temperature characteristics, and enhancing high-temperature accelerated life through Cu diffusion into the ceramic layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If glass is added to lower the sintering temperature, then the sintering temperature is reduced, but the permittivity is lowered
Solution Approach 1:
The invention changes the chemical composition parameters of the dielectric ceramic layer by specifying precise ranges of BaTiO3 (95-99.5 mol%), Re2O3 (0.05-0.75 mol%), and MnO (0.25-2.0 mol%), along with controlled amounts of B, Li, or Si (0.16-1.6 parts by mass). This compositional parameter optimization enables sintering at lower temperatures (1080°C or less) while maintaining high permittivity (2000 or more), resolving the trade-off between temperature reduction and permittivity preservation
Solution Approach 2:
The invention creates a composite dielectric ceramic system combining BaTiO3 base material with rare earth metal oxides (Re2O3 where Re is La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y) and MnO, along with subcomponents containing B, Li, or Si. This composite material structure achieves both low-temperature sinterability and high permittivity, overcoming the limitation of glass addition that reduced permittivity
2Reliability
If additives are added to improve reduction resistance, then the reduction resistance is improved, but the sinterability of the ceramic material is deteriorated
Solution Approach 1:
The invention optimizes the concentration parameters of additives by limiting Re2O3 to 0.05-0.75 mol% and MnO to 0.25-2.0 mol% relative to 100 mol% BaTiO3, with B, Li, or Si subcomponents at 0.16-1.6 parts by mass. This precise parameter control provides sufficient reduction resistance while maintaining good sinterability at temperatures of 1080°C or less, resolving the contradiction between improvement of one property and deterioration of another
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 achieves a multi-layer ceramic capacitor with permittivity of 2000 or more, X7R temperature characteristics, and improved high-temperature accelerated life, comparable to existing Ni internal electrode capacitors, while being lead-free and sinterable at reduced temperatures.
Implementation Method 1
Cu diffuses from an internal electrode and distributes
Implementation Method 2
a dielectric ceramic layer having a specific composition and an internal electrode constituted of Cu or a Cu alloy are combined, 1080°C or less, desirably substantially 1000°C can be used to sinter
Data Source
AI summary
A multi-layer ceramic capacitor includes a plurality of dielectric ceramic layers; internal electrodes formed between the dielectric ceramic layers; and end termination electrodes electrically connected to the internal electrodes, wherein the dielectric ceramic layer is a sintered body constituted of a primary component that, when it is expressed by ABO3+aRe2O3+bMnO, satisfies 1.000≦A/B≦1.035, 0.05≦a≦0.75 and 0.25≦b≦2.0; and a subcomponent that includes at least one kind of B, Li or S in the range of 0.16 to 1.6 parts by mass in total in terms of B2O3, Li2O and SiO2; and the internal electrode is constituted of Cu or a Cu alloy.