Multilayer Ceramic Capacitor Electrode Structure for Moisture Crack Resistance
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Solution Overview
Problem
Multilayer ceramic capacitors face insufficient moisture resistance reliability due to the occurrence of cracks in external electrodes, which compromises their electrical conductivity and reliability.
Innovation Solution
The capacitors feature a multilayer body with dielectric and internal electrodes alternately stacked, and external electrodes comprising a metal layer, a glass film adjacent to the metal layer, a fired layer of glass and metal, and a plating film, with specific thicknesses and configurations to enhance moisture resistance and prevent cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external electrodes are formed on multilayer ceramic capacitors, then electrical connectivity is achieved, but moisture resistance reliability becomes insufficient due to crack occurrence
Solution Approach 1:
The external electrode is constructed as a composite structure with multiple layers: a base metal layer for electrical conductivity, an intermediate layer (oxide or glass-based) for adhesion and stress management, and an outer protective layer (glass or ceramic) for moisture resistance. This composite approach allows each layer to address specific requirements, preventing cracks while maintaining electrical functionality.
Solution Approach 2:
The patent optimizes the thickness parameters of each external electrode layer to prevent crack formation. The intermediate layer thickness is controlled at 0.1-5.0 μm, and the outer protective layer is designed with specific thickness ranges to manage thermal stress and mechanical strength, thereby improving moisture resistance reliability without compromising electrical connectivity.
2Reliability
If the external electrode structure is simplified, then manufacturing complexity is reduced, but moisture resistance reliability deteriorates
Solution Approach 1:
The external electrode is segmented into distinct functional layers: a base metal layer for electrical conductivity, an intermediate layer for adhesion and stress management, and an outer protective layer for moisture resistance. This segmentation allows each layer to be optimized for its specific function while maintaining overall structural integrity and reliability.
Solution Approach 2:
An intermediate layer is introduced between the base metal layer and the outer protective layer to serve as a mediator. This intermediate layer (oxide or glass-based) provides adhesion between layers, manages thermal stress, and prevents direct contact between the metal and moisture-prone environments, thereby improving reliability without significantly increasing manufacturing complexity.
Data Source
AI summary
A multilayer ceramic capacitor includes external electrodes including metal layers on first and second end surfaces and covering internal electrodes extending to the first and second end surfaces, respectively, glass films on the first and second end surfaces, adjacent to the metal layers and extending around the metal layers, fired layers including glass and metal, and covering the metal layers, and plating films covering the fired layers. A thickness of the metal layer is between about 0.1 μm and about 15.0 μm inclusive, and a thickness of the fired layer is between about 0.1 μm and about 1.0 μm inclusive.