Multilayer Ceramic Capacitor Grain Size Control
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Solution Overview
Problem
The challenge is to maintain the capacitance and capacity vs. temperature characteristics of multilayer ceramic capacitors without worsening them when the internal electrode layer is made thinner, as finer ceramic grains used to achieve thinner dielectric layers result in a lower specific dielectric constant.
Innovation Solution
Incorporating coarse ceramic grains with a specific size range (Tmin≦Dcoa≦Tmax) and volume percentage (25-50%) in the dielectric layer, along with controlled average grain size (0.15×Tabe≦Dabe≦0.3×Tabe), to ensure the dielectric layer's thickness and composition do not negatively impact capacitance and capacity vs. temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If finer ceramic grains are used to make the dielectric layer thinner, then the capacitance and capacity vs. temperature characteristics deteriorate due to lower specific dielectric constant
Solution Approach 1:
The patent applies local quality by creating a bimodal grain size distribution where coarse ceramic grains (first size range) and fine ceramic grains (second size range) coexist in the dielectric layer. The coarse grains provide high specific dielectric constant to maintain capacitance characteristics, while the fine grains enable thinner dielectric layer construction. This spatial coexistence of grains with different properties resolves the contradiction between thickness reduction and performance maintenance.
Solution Approach 2:
The patent employs composite materials principle by combining ceramic grains of two distinct size ranges within the same dielectric layer. The composite structure consists of coarse grains (0.5-2.0 μm) that contribute to dielectric constant and fine grains (0.1-0.5 μm) that enable thinning. This composite approach allows the dielectric layer to simultaneously achieve reduced thickness and maintained capacitance characteristics.
2Volume of moving object
If the internal electrode layer is made thinner to reduce capacitor size, then the dielectric layer must also be made thinner, but this causes capacitance deterioration
Solution Approach 1:
The patent applies local quality by creating a bimodal grain size distribution where coarse ceramic grains (first size range) and fine ceramic grains (second size range) coexist in the dielectric layer. The coarse grains provide high specific dielectric constant to maintain capacitance characteristics, while the fine grains enable thinner dielectric layer construction. This spatial coexistence of grains with different properties resolves the contradiction between thickness reduction and performance maintenance.
Solution Approach 2:
The patent employs composite materials principle by combining ceramic grains of two distinct size ranges within the same dielectric layer. The composite structure consists of coarse grains (0.5-2.0 μm) that contribute to dielectric constant and fine grains (0.1-0.5 μm) that enable thinning. This composite approach allows the dielectric layer to simultaneously achieve reduced thickness and maintained capacitance characteristics.
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 prevents the deterioration of capacitance and capacity vs. temperature characteristics while allowing for thinner internal electrode layers, maintaining performance and reducing the risk of short-circuiting.
Implementation Method 1
with such strong dielectric ceramic grains, however, a smaller grain size means a lower specific dielectric constant because of the sizing effect
Data Source
AI summary
A multilayer ceramic capacitor includes ceramic grains forming a dielectric layer of the multilayer ceramic capacitor, which ceramic grains contain a coarse ceramic grain SPr having a coarse grain size Dcoa that satisfies the condition of Tmin ≦Dcoa ≦Tmax where Tmax is the maximum thickness of the dielectric layer and Tmin is the minimum thickness of the dielectric layer. The multilayer ceramic capacitor is capable of inhibiting deterioration of capacitance and capacity-temperature characteristics even when the internal electrode layer is made thin.