Multilayer Ceramic Component External Terminal Bonding
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in reducing size while maintaining performance and preventing short-circuiting due to thin ceramic layers, and existing methods for forming external terminal electrodes either result in inadequate bonding or increased thickness.
Innovation Solution
The use of a Cu plating film with dispersed Cu oxides, particularly Cu2O, on the external terminal electrodes, which are formed by plating and subjected to a heat treatment at 1,065°C or more in an oxygen-rich atmosphere to enhance bonding to the ceramic base body, along with auxiliary conductors and edge-side conductors for improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of ceramic layers is decreased to reduce component size, then the capacity can be increased, but short-circuiting occurs between internal electrodes
Solution Approach 1:
The patent applies different material compositions to different regions of the ceramic layer. Specifically, the first and second ceramic layers contain different amounts of glass (first glass content and second glass content respectively), creating local quality variations that prevent short-circuiting while maintaining thin overall thickness. This regional differentiation allows the thin ceramic structure to maintain sufficient insulation properties.
2Area of moving object
If the area of ceramic layer is increased to provide margins for stacking errors, then the effective area of internal electrode can be increased, but the component size exceeds predetermined standards
Solution Approach 1:
The patent changes the material parameters of the ceramic layers, specifically the glass content, to alter the shrinkage characteristics during firing. By controlling the glass content in different layers, the patent achieves precise dimensional control that allows for adequate margins while maintaining the overall component size within predetermined standards.
3Ease of manufacture
If conductive paste is applied by immersion method, then the external terminal electrode can be formed, but the paste adheres thick to the central part increasing electrode thickness
Solution Approach 1:
The patent changes the physical parameters of the conductive paste by adjusting its viscosity. By controlling the viscosity within a specific range, the paste achieves optimal flow characteristics that prevent excessive thickening at the central region during immersion application, resulting in more uniform electrode thickness.
4Shape
If plating method is used to form external terminal electrode, then thin and flat electrode can be formed, but the bonding force to ceramic base body is insufficient
Solution Approach 1:
The patent creates a composite structure at the interface between the external terminal electrode and the ceramic base body. By controlling the glass content in the first and second ceramic layers, a composite material system is formed that enhances the bonding force between the plating film and the ceramic, combining the advantages of both plating (thin and flat) and glass bonding (strong adhesion).
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 approach allows for the creation of thin, flat external terminal electrodes with superior bonding to the ceramic base body, enabling reduced component size and increased capacity within predetermined dimensional standards, while enhancing reliability and humidity resistance.
Implementation Method 1
subjected to a heat treatment at 1,065°C or more in an oxygen-rich atmosphere to enhance bonding to the ceramic base body
Implementation Method 2
Cu plating film with dispersed Cu oxides, particularly Cu2O
Data Source
AI summary
A multilayer ceramic electronic component including thin external terminal electrodes each having a superior bonding force to a ceramic base body is provided. In order to form the external terminal electrodes, after Cu plating films are deposited on exposed portions of internal electrodes by direct plating on a ceramic base body, a Cu liquid phase, an O2-containing liquid phase, and a Cu solid phase are generated between the Cu plating film and the ceramic base body by a heat treatment, so that Cu oxides are dispersed in the Cu plating film, at least near an interface with the ceramic base body. Since the Cu oxides function as an adhesive, a bonding force of the Cu plating film to the ceramic base body can be increased, and hence the external terminal electrode having a superior bonding force to the ceramic base body can be obtained.