Curved Internal Electrodes in Multilayer Ceramic Capacitors
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Solution Overview
Problem
Multilayer ceramic capacitors with dielectric layers containing Ca and Zr experience dielectric breakdown when subjected to high voltages, limiting their application.
Innovation Solution
The design incorporates a multilayer ceramic capacitor with internal electrode layers and dielectric layers made of CaZrO3, where the internal electrode layers have a curved end side extending in the width direction, reducing the likelihood of dielectric breakdown by avoiding corner concentrations of electric field, and including Ti in the dielectric layers to enhance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dielectric layers including Ca and Zr are used to reduce resistive temperature coefficient, then temperature stability of capacitance is improved, but dielectric breakdown occurs when high voltage is applied
Solution Approach 1:
The internal electrode layers are designed with curved end sides instead of straight edges. The curvature is defined by the relationship L2 < L1, where L1 is the length at the middle portion and L2 is the length at the end portion in the width direction. This curved configuration eliminates sharp corners that would concentrate electric fields, thereby preventing dielectric breakdown while maintaining the Ca-Zr dielectric composition for temperature stability.
Solution Approach 2:
The patent applies different geometric characteristics to different portions of the internal electrode layers. The middle portion has a longer extent (L1) while the end portions have a shorter extent (L2), creating a localized curvature at the ends. This local quality modification specifically addresses the electric field concentration problem at corners without altering the overall electrode structure or dielectric material composition.
2Ease of manufacture
If internal electrode layers have straight edges, then manufacturing is simpler, but electric field concentration at corners causes dielectric breakdown
Solution Approach 1:
The internal electrode layers incorporate curved end sides with a specific geometric relationship (L2 < L1) to eliminate corner sharpness. This curvature design prevents electric field concentration that would lead to dielectric breakdown, while the overall lamination structure remains suitable for conventional manufacturing processes.
Solution Approach 2:
The patent modifies the geometric parameters of the internal electrode layers by defining the relationship between L1 (middle portion length) and L2 (end portion length). This parameter change from equal lengths (straight edges) to unequal lengths (curved edges) transforms the electrode geometry to prevent dielectric breakdown while maintaining manufacturability.
Data Source
AI summary
A multilayer ceramic capacitor includes internal electrode layers and dielectric layers laminated alternately, and external electrodes on end surfaces. The internal electrode layers extend in a length direction and a width direction. The dielectric layers include about 100 moles or more and about 101 moles or less of Ca with respect to 100 moles of Zr. One side in the length direction of the internal electrode layers is connected to one of the external electrodes. Another side of the internal electrode layers is not connected to the external electrodes. A length at a middle portion in the width direction of the internal electrode layers is defined as L1, and a length at an end portion in the width direction is defined as L2, the internal electrode layers include a curved end side extending in the width direction so that L2<L1 is satisfied.