Multilayer Ceramic Capacitor Electrode Structure for Narrow Lead-Outs
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face reduced connectivity between internal electrode lead-out portions and external electrodes due to narrow lead-out portions, leading to decreased contact areas and potential connectivity issues.
Innovation Solution
The design incorporates a configuration where the lead-out portions of internal electrode layers have a narrower width than the opposing portions, with a Cu layer having a higher content in the first layer portion and a glass-rich layer in the second layer portion, enhancing connectivity and contact areas through a Cu-rich and glass-rich layer structure, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the lead-out portion width is reduced, then the capacitance density is improved, but the contact area with external electrode is reduced
Solution Approach 1:
The external electrode is designed with non-uniform Cu content distribution, creating a Cu-rich first layer portion for enhanced connectivity and a glass-rich second layer portion for protection. This local quality variation allows the electrode to simultaneously achieve low impedance connection and environmental stability without requiring increased overall electrode width
Solution Approach 2:
The external electrode uses a composite structure combining Cu-rich and glass-rich layers. The Cu-rich first layer portion provides excellent electrical connectivity with the lead-out portion, while the glass-rich second layer portion provides moisture resistance and mechanical protection, resolving the contradiction between contact area requirements and capacitance density
2Quantity of substance
If the lead-out portion width is reduced, then the capacitance density is improved, but the connectivity is reduced
Solution Approach 1:
The invention changes the compositional parameters of the external electrode by creating a Cu-rich first layer portion with higher copper content. This parameter change enhances the electrical conductivity and connectivity with the narrow lead-out portion, allowing reliable signal transmission despite the reduced width
Solution Approach 2:
By creating a localized Cu-rich region in the first layer portion that directly contacts the lead-out portion, the invention ensures high connectivity at the critical interface while maintaining narrow overall electrode dimensions for improved capacitance density
3Reliability
If a Cu-rich first layer portion is added, then the connectivity is improved, but the device complexity is increased
Solution Approach 1:
The invention merges the functions of connectivity enhancement and environmental protection into a single integrated external electrode structure with two functional layers. This combined approach avoids the need for separate components or additional processing steps, thereby limiting the increase in device complexity while achieving improved connectivity
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 configuration improves the connectivity and reliability of multilayer ceramic capacitors by increasing the contact area between internal electrode layers and external electrodes, reducing delamination, and enhancing moisture resistance.
Implementation Method 1
The first layer portion of the first external electrode is a layer in which Cu is continuous to connect the first lead-out portions adjacent to each other in the thickness direction
Implementation Method 2
Each of the first external electrode and the second external electrode includes a Cu layer on the element body portion, a Ni plating layer on the Cu layer
Implementation Method 3
The second layer portion has a higher content of a glass than the first layer portion... enhancing moisture resistance
Data Source
AI summary
A multilayer ceramic capacitor includes an element body portion including internal electrode layers, and first and second external electrodes. In the internal electrode layers, a width of an opposing portion is larger than a width of a lead-out portion, each of the first and second external electrodes includes a Cu layer on the element body portion including first and second layer portions. The first layer portion has a higher Cu content than the second layer portion, the second layer portion has a higher glass content than the first layer portion. The Cu in the first layer portion is continuous to connect lead-out portions adjacent to each other. In a cross section of the second layer portion extending through a central portion in the width direction and parallel to the thickness and length directions, the glass occupies about 25% or more of an area of the second layer portion.