Inflected External Electrodes for Ceramic Capacitor Downsizing
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Solution Overview
Problem
Ceramic electronic devices, such as three-terminal multilayer ceramic capacitors, face challenges in downsizing while maintaining humidity resistance and capacity, as reducing external electrode thickness compromises humidity resistance.
Innovation Solution
A ceramic electronic device design featuring multilayer chips with internal electrode layers and external electrodes where the external electrodes have varying thicknesses, with a larger thickness connected to projection portions and a smaller thickness elsewhere, along with a manufacturing method involving pattern-formed sheets and conductive pastes to enhance wettability and firing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the external electrode thickness is reduced to downsize the ceramic electronic device, then the external size is reduced, but the humidity resistance deteriorates
Solution Approach 1:
The external electrode is designed with non-uniform thickness distribution, having a first thickness in a first region and a second thickness in a second region, where the thickness varies continuously or stepwise. This local quality variation allows the electrode to provide enhanced humidity resistance in critical regions while maintaining overall compact dimensions, thereby resolving the contradiction between downsizing and humidity resistance.
2Reliability
If the external electrode thickness is increased to improve humidity resistance, then the humidity resistance is improved, but the external size increases
Solution Approach 1:
Instead of uniformly increasing the external electrode thickness throughout, the invention applies increased thickness locally in specific regions where humidity resistance is most critical, while maintaining thinner sections in other areas. This selective thickness distribution achieves the required humidity resistance without proportionally increasing the overall device volume.
3Volume of moving object
If the ceramic electronic device is downsized to meet small size mobile phone requirements, then the space saving is achieved, but the capacity enlargement becomes difficult
Solution Approach 1:
The invention optimizes the thickness dimension of the external electrode by creating a multi-level thickness structure rather than relying solely on increasing the area or volume of electrode material. This dimensional optimization allows for enhanced capacity and humidity resistance within the constrained lateral dimensions of downsized devices, effectively utilizing the thickness dimension to compensate for reduced planar area.
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 design secures humidity resistance and suppresses external size while enabling capacity enlargement and downsizing, maintaining desirable performance with a small number of elements.
Implementation Method 1
wettability of the conductive paste for an external electrode with respect to the reverse pattern slurry is higher than wettability of the conductive paste for an external electrode with respect to the conductive paste for an internal electrode
Implementation Method 2
firing the ceramic multilayer structure and the conductive paste for an external electrode
Data Source
AI summary
A ceramic electronic device includes: a multilayer chip in which dielectric layers are stacked, the multilayer chip having two end faces, an upper face, a lower face and two side faces; a plurality of internal electrode layers that are provided inside of the multilayer chip; and a pair of external electrodes that are provided on the two end faces and are connected to the plurality of internal electrode layers, wherein each of the pair of external electrodes has a smaller thickness in a region not connected to the plurality of internal electrode layers, has an inwardly inflected point as viewed toward the plurality of internal electrode layers, and has a larger thickness in a region connected to the plurality of internal electrode layers, as measured in a direction perpendicular to the corresponding end face.