Multilayer Ceramic Capacitor Electrode Porosity Design
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Solution Overview
Problem
High-capacity multilayer ceramic capacitors face durability issues due to reduced volume and strength of dielectric layers and potential cracking during high-temperature sintering, particularly due to differences in metal diffusion rates between internal and external electrodes.
Innovation Solution
The multilayer electronic component incorporates external electrodes with a first layer containing conductive metal, glass, low melting point metal, and pores, and a second layer with conductive metal and glass, where the porosity of the first layer is higher than the second layer, to reduce sintering temperature and prevent cracking while maintaining connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of layers is increased to achieve high capacity, then the capacity increases, but the volume and strength of dielectric layers decrease leading to durability limits
Solution Approach 1:
The external electrode is divided into two distinct layers: a first external electrode layer with higher porosity containing low melting point metal, and a second external electrode layer with lower porosity. This segmentation allows each layer to perform specialized functions - the first layer reduces sintering temperature and prevents cracking, while the second layer provides structural strength and conductivity.
Solution Approach 2:
Different regions of the external electrode are given different properties through the two-layer structure. The first layer (higher porosity) is optimized for reducing sintering temperature and preventing cracks during the sintering process, while the second layer (lower porosity) is optimized for providing mechanical strength and electrical conductivity after sintering.
2Reliability
If sintering is performed at high temperature to ensure connectivity, then the connectivity is improved, but cracks occur due to difference in diffusion rates of metal between internal and external electrodes
Solution Approach 1:
The sintering temperature is reduced by incorporating low melting point metal in the first external electrode layer. This parameter change allows the sintering process to occur at a lower temperature, reducing the thermal stress and diffusion rate differences that cause cracking, while still achieving adequate connectivity between internal and external electrodes.
Solution Approach 2:
The first external electrode layer containing low melting point metal acts as an intermediary between the internal electrode and the second external electrode layer. This intermediate layer facilitates connectivity at lower temperatures and reduces the direct thermal stress and diffusion rate differences between the internal electrode and the outer electrode structure.
3Temperature
If the porosity of the first electrode layer is increased to reduce sintering temperature, then the sintering temperature decreases, but the structural strength may be compromised
Solution Approach 1:
The external electrode is segmented into two layers with different porosity levels. The first layer has higher porosity to reduce sintering temperature, while the second layer has lower porosity to provide structural strength. This segmentation resolves the contradiction by distributing the functional requirements across separate layers.
Solution Approach 2:
The external electrode is formed as a composite structure with two layers having different material properties. The first layer (higher porosity) and second layer (lower porosity) are combined to create a composite electrode that exhibits both low sintering temperature characteristics and high structural strength.
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 enhances the durability and reliability of the multilayer ceramic capacitors by lowering the sintering temperature, reducing crack occurrence, and maintaining electrical connectivity, thereby improving the component's moisture resistance and overall performance.
Implementation Method 1
there is a problem in that a crack may occur due to a difference in diffusion rates of metal between an internal electrode and an external electrode
Implementation Method 2
a low melting point metal having a lower melting point than the conductive metal
Implementation Method 3
the porosity of the first electrode layer is higher than the porosity of the second electrode layer
Data Source
AI summary
A multilayer electronic component includes a body including a dielectric layer and internal electrodes alternately stacked with the dielectric layer interposed therebetween; and an external electrode including a first electrode layer disposed externally on the body, connected to the internal electrodes, and including a conductive metal, a glass, a low melting point metal having a lower melting point than the conductive metal, and a pore, and a second electrode layer covering the first electrode layer and including a conductive metal, a glass, and a pore, wherein porosity of the first electrode layer is higher than porosity of the second electrode layer.