Multilayer Ceramic Capacitor Electrode Structure for Moisture Protection
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Solution Overview
Problem
In multilayer ceramic electronic components, the decreasing size and increasing capacitance lead to thinner internal electrodes and lower equivalent series resistance (ESR), causing impedance issues at parallel resonance points, which degrades the decoupling function in certain frequency bands, and creates vulnerabilities to moisture penetration due to external electrode wrapping around side surfaces.
Innovation Solution
A multilayer ceramic electronic component design featuring a ceramic body with a specific external electrode structure, including a first conductive portion on the end surface that does not wrap around the side surfaces and a second conductive portion that covers the first portion and wraps around the principal and side surfaces, along with protruding portions to enhance stability and prevent moisture penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the external electrode wraps around onto the side surface to cover the resistance electrode layer, then the coverage and protection of the resistance electrode layer is improved, but the distance from the edge of the wrapped around portion of the external electrode layer to the edge of the wrapped around portion of the resistance electrode layer becomes short, making it easy for moisture to penetrate
Solution Approach 1:
The invention introduces a protruding portion that extends in the thickness direction from the end surface, creating a three-dimensional structure. This dimensional change allows the external electrode to form an overlapping region with the resistance electrode layer in the thickness direction, rather than only in the planar direction, thereby providing better coverage and longer moisture barrier distance without increasing the planar wrapping extent.
2Quantity of substance
If multilayer ceramic capacitors are made smaller with increasing capacitance, then the capacitance density is improved, but the internal electrodes become thinner and ESR becomes too low, causing high impedance at parallel resonance points and degrading decoupling function
Solution Approach 1:
The invention changes the electrical parameters of the external electrode by introducing a resistance electrode layer with controlled resistance value. This resistance layer is electrically connected to the internal electrode, allowing adjustment of the overall ESR to an optimal range that prevents excessive impedance at parallel resonance points while maintaining the required capacitance value in smaller capacitor designs.
3Reliability
If a resistance electrode layer is formed by applying paste containing resistive component and covered by external electrode layer, then the ESR is increased to counter anti-resonance, but the wrapped around structure creates short distance edges that facilitate moisture penetration
Solution Approach 1:
The invention extends the external electrode structure in the thickness direction to form a protruding portion, creating an overlapping region with the resistance electrode layer. This three-dimensional configuration provides both adequate coverage of the resistance electrode layer and sufficient edge distance to prevent moisture penetration, resolving the contradiction between ESR control and moisture protection.
Solution Approach 2:
The protruding portion of the external electrode acts as an intermediary structure that simultaneously provides coverage for the resistance electrode layer and creates a moisture barrier. This intermediate structure allows the resistance electrode layer to perform its ESR control function while being protected from moisture by the overlapping external electrode portion.
Data Source
AI summary
In a multilayer ceramic electronic component, internal electrodes arranged inside a ceramic body include exposed ends that are connected to end surfaces of the ceramic body. External electrodes, which are arranged on the end surfaces so as to be electrically connected to the internal electrodes, include first conductive portions that are arranged on the end surfaces so as to cover the exposed ends but so as not to wrap around onto the side surfaces, and include second conductive portions that are arranged on the end surfaces so as to cover the first conductive portions and so as to wrap around onto the principal surfaces and the side surfaces. In each external electrode, protruding portions are arranged on the end surface adjacent to the first conductive portion to stabilize the posture of the ceramic body when the second conductive portions are being formed.