Multilayer Ceramic Capacitor Electrode Design for Solder Splitting
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Solution Overview
Problem
Existing multilayer ceramic capacitors face issues with solder splitting phenomena due to glass segregation and increased dielectric loss at high frequencies, particularly when using iron group transition metals like Ni for plating, which affects sealing and electrical characteristics.
Innovation Solution
A multilayer ceramic capacitor design with a base conductive layer containing less than 7 weight % glass and composed of transition metals other than the iron group, along with a first plated film that is half the thickness of the base conductive layer or more, primarily made of transition metals like Cu, to prevent solder splitting and reduce dielectric loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass is added to external electrode paste to prevent intrusion of plating solution, then seal property is improved, but surface elution of glass occurs causing inferior plating after sintering
Solution Approach 1:
The patent changes the chemical composition parameters of the glass by specifying precise ratios of network formers (SiO2: 40-70 wt%, B2O3: 10-30 wt%) and network modifiers (Al2O3: 5-20 wt%, ZnO: 5-20 wt%). This compositional optimization ensures the glass provides adequate seal properties while minimizing surface elution that would cause plating defects.
Solution Approach 2:
The external electrode paste is formulated as a composite material containing conductive metal particles (Cu, Ag, or Au) combined with the optimized glass composition. This composite structure allows the glass to provide sealing functionality while the metal particles maintain electrical conductivity, and the specific glass composition prevents excessive surface elution during sintering.
2Reliability
If iron group transition metal (Ni) is used for plated film to ensure adhesiveness, then electrode sealing is improved, but dielectric loss increases at high frequencies
Solution Approach 1:
The patent changes the material parameter of the plated film from iron group transition metals (Ni) to non-ferromagnetic metals (Cu, Ag, or Au). This material substitution eliminates the high magnetic permeability characteristic of Ni, thereby reducing dielectric loss at high frequencies while maintaining adequate electrode sealing through the base conductive layer.
Solution Approach 2:
The patent applies different material properties to different layers of the external electrode structure. The base conductive layer (containing glass) provides sealing functionality, while the plated film layer (Cu, Ag, or Au) provides low-loss electrical conductivity. This local differentiation of material quality allows each layer to optimize its specific function without compromising the other.
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 solution effectively suppresses solder splitting and enhances high-frequency characteristics by ensuring adequate adhesiveness and reducing dielectric loss, while maintaining preferable electrode sealing and plating quality.
Implementation Method 1
the base conductive layer including glass of less than 7 weight % and being mainly composed of a transition metal other than an iron group or a noble metal
Implementation Method 2
a first plated film covering the base conductive layer, the first plated film having a thickness that is half of a thickness of the base conductive layer or more and being mainly composed of a transition metal other than an iron group
Data Source
AI summary
A multilayer ceramic capacitor includes: a ceramic multilayer structure having ceramic dielectric layers and internal electrode layers alternately stacked, the internal electrode layers being mainly composed of a transition metal other than an iron group, end edges of the internal electrode layers being alternately exposed to a first end face and a second end face; and a pair of external electrodes provided on the first end face and the second end face, wherein the external electrode includes a base conductive layer that includes glass of less than 7 weight % and is mainly composed of a transition metal other than an iron group or a noble metal, and a first plated film that covers the base conductive layer, has a thickness that is half of a thickness of the base conductive layer or more and is mainly composed of a transition metal other than an iron group.