Multilayer Capacitor External Electrode Glass for Plating Reliability
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face issues with deteriorated electrode coverage, corrosion resistance, and moisture resistance due to thin external electrodes, which are prone to glass erosion and delamination during plating, leading to poor reliability and increased surface roughness.
Innovation Solution
Incorporating a secondary phase of glass comprising barium (Ba), aluminum (Al), and silicon (Si) into the external electrode to enhance density, corrosion resistance, and moisture resistance, while preventing glass pooling and improving plating reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin external electrode is formed with conventional external electrode paste, then miniaturization and high capacitance are achieved, but electrode coverage is deteriorated due to increased surface roughness
Solution Approach 1:
The patent changes the chemical composition parameters of the glass component in the external electrode paste, specifically adjusting the ratio of alkali metal oxides to alkaline earth metal oxides and controlling the content of specific glass formers. This parameter optimization allows the external electrode to maintain good coverage and adhesion even when thinned, resolving the contradiction between miniaturization and electrode coverage.
Solution Approach 2:
The patent uses a composite material system consisting of conductive metal particles, glass frit, and organic vehicle. The glass component serves as a binder and densifier that compensates for the reduced thickness of the external electrode, maintaining coverage and adhesion properties. The composite structure allows the thin electrode to achieve both miniaturization and sufficient coverage.
2Strength
If glass component is added to improve bonding strength between external electrode and body, then bonding strength is enhanced, but corrosion resistance deteriorates due to vulnerability to acid plating solution
Solution Approach 1:
The patent optimizes the chemical composition parameters of the glass component, specifically controlling the ratio of alkali metal oxides (Na2O, K2O) to alkaline earth metal oxides (CaO, MgO) to be within 0.5-2.0, and limiting water-soluble glass content to 3-15 wt%. These parameter changes enable the glass to provide strong bonding while resisting corrosion from acid plating solutions, resolving the contradiction between bonding strength and corrosion resistance.
Solution Approach 2:
The patent creates different glass phase compositions within the external electrode - a corrosion-resistant glass phase at the surface exposed to plating solution, and a bonding-optimized glass phase at the interface with the ceramic body. This local differentiation allows the single glass component to simultaneously provide both strong bonding and corrosion resistance.
3Manufacturing precision
If glass component is used to achieve high density on surface of external electrode, then surface density is improved, but moisture resistance reliability deteriorates due to partial damage from acid plating solution
Solution Approach 1:
The patent adjusts the glass composition parameters to achieve optimal surface density while maintaining corrosion and moisture resistance. Specifically, controlling the total content of glass formers (SiO2, B2O3, P2O5) at 70-90 wt% and limiting water-soluble glass to 3-15 wt% creates a dense yet corrosion-resistant surface layer that prevents moisture penetration, resolving the contradiction between surface density and moisture resistance reliability.
4Volume of moving object
If external electrode is thinned to achieve miniaturization, then size is reduced, but reliability deteriorates due to glass erosion and delamination during plating process
Solution Approach 1:
The patent optimizes the glass component parameters including the ratio of network formers to modifiers, controlling the softening temperature and viscosity of the glass. This parameter optimization ensures that during the plating process, the glass forms a stable, erosion-resistant matrix that prevents delamination even in thinned electrodes, maintaining plating reliability while enabling miniaturization.
Solution Approach 2:
The patent creates a composite external electrode structure where conductive metal particles are embedded in an optimized glass matrix. This composite structure provides both the electrical conductivity needed for thin electrodes and the mechanical stability to prevent erosion and delamination during plating, resolving the contradiction between miniaturization and plating reliability.
Data Source
AI summary
A multilayer electronic component includes a body including a dielectric layer and an internal electrode; and an external electrode disposed on the body and connected to the internal electrode, wherein the external electrode includes a conductive metal and glass, and wherein at least a portion of the glass includes a secondary phase of the glass including barium (Ba), aluminum (Al), and silicon (Si).