Multilayer Ceramic Component Electrodes With Segmented Cu Plating
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Solution Overview
Problem
The adhesive strength between the multilayer body and the plating layer of external electrodes in multilayer ceramic electronic components is weakened, leading to peeling-off issues, and the mechanical strength of the plating layer is compromised due to grain growth during heat treatment, affecting the reliability and performance of these components.
Innovation Solution
The external electrodes are structured with specific Cu plating layers having controlled Cu particle densities and additional Cu plating layers to enhance adhesive strength and mechanical strength, while maintaining low equivalent series resistance (ESR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed to improve adhesive strength between the multilayer body and the plating layer, then adhesive strength is improved, but grain growth in the metal component causes mechanical strength of the plating layer to decrease
Solution Approach 1:
The external electrode is divided into multiple plating layers (first plating layer, second plating layer, and third plating layer) with different Cu particle densities. The first and second plating layers have low Cu particle density (1.5 or less) to provide high adhesive strength, while the third plating layer has high Cu particle density to provide high mechanical strength. This segmentation allows each layer to specialize in one function, resolving the contradiction between adhesive strength and mechanical strength.
Solution Approach 2:
Different regions of the plating structure are given different local qualities through controlled Cu particle densities. The first and second plating layers have low Cu particle density (1.5 or less) optimized for adhesion to the multilayer body and intermediate layer, while the third plating layer has high Cu particle density optimized for mechanical strength and resistance to grain growth. This local differentiation allows the structure to simultaneously achieve both adhesive strength and mechanical strength.
2Volume of moving object
If the external electrode is plated directly on the end surface of the multilayer body, then the external electrode can be planarized and reduced in thickness, but the adhesive strength between the multilayer body and the plating layer is weakened
Solution Approach 1:
An intermediate layer is introduced between the multilayer body and the first plating layer to serve as a mediator that enhances adhesion. This intermediate layer facilitates better bonding between the multilayer body and the plating structure, resolving the adhesion problem that would otherwise result from direct plating. The intermediate layer acts as a bridge that maintains both the reduced thickness and improved adhesive strength.
3Strength
If Cu particle density is increased to improve mechanical strength of the plating layer, then mechanical strength is improved, but adhesive strength between the plating layer and multilayer body decreases
Solution Approach 1:
The plating structure is segmented into multiple layers with different Cu particle densities. The first and second plating layers have low Cu particle density (1.5 or less) to ensure high adhesive strength, while the third plating layer has high Cu particle density to ensure high mechanical strength. This segmentation allows the structure to simultaneously achieve both adhesive strength and mechanical strength without compromise.
Solution Approach 2:
Different local regions of the plating structure have different Cu particle densities optimized for their specific functions. The first and second plating layers have low Cu particle density (1.5 or less) locally optimized for adhesion, while the third plating layer has high Cu particle density locally optimized for mechanical strength. This local quality differentiation resolves the contradiction by allowing each region to excel at its primary function.
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 improved adhesive strength and mechanical strength of the external electrodes enhance the reliability and performance of multilayer ceramic electronic components, reducing the risk of peeling and fractures, and lowering ESR.
Implementation Method 1
an average number of Cu particles is about 1.5 or less in any two or more first square regions of the first Cu plating layer on a side of the first end surface... The first external electrode includes a first Cu plating layer and a third Cu plating layer on the first Cu plating layer
Implementation Method 2
a heat treatment is performed after the external electrode is formed by plating directly on the multilayer body. This causes mutual diffusion between the metal of the internal electrode layer and the metal of the plating layer
Implementation Method 3
the heat treatment causes growth of grains in the metal component in the plating layer, with the result that the mechanical strength of the plating layer decreases
Data Source
AI summary
A multilayer ceramic electronic component includes a multilayer body including first and second internal electrode layers extending first and second end surfaces, first and second external electrodes respectively on the first and second end surfaces and respectively connected to the first and second internal electrode layers. The first external electrode includes first and third Cu plating layers, the second external electrode includes second and fourth Cu plating layers. Average numbers of Cu particles are about 1.5 or less in two or more first or second square regions of the first and second Cu plating layers. Average numbers of Cu particles are more than about 1.5 in two or more third or fourth square regions of the third and fourth Cu plating layer. The first square regions to the fourth square regions each has a square or substantially square shape with each side having a dimension of about 2 μm.