Multilayer Ceramic Electrode Structure for Migration Resistance
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Solution Overview
Problem
Existing varistors face challenges with reduced size and increased operating frequency, leading to capacitance variations and migration issues due to residual stress in silver-based external electrodes, which can cause peeling and exposure of silver, increasing the risk of migration.
Innovation Solution
A multilayer ceramic component with a sintered body, internal electrodes, and side surface electrodes featuring a primary electrode layer with a plating layer, where the primary electrode layer is partially separated from the sintered body to create an air gap, reducing residual stress and preventing silver exposure, thereby minimizing migration risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the overall size of the varistor is reduced, then the component size is minimized, but the distance between external electrodes becomes shorter and residual stress causes peeling and silver exposure
Solution Approach 1:
The external electrode is segmented into multiple functional layers: a silver-based primary electrode layer for electrical conductivity, and an additional protective layer (such as aluminum or copper) that prevents peeling and silver exposure. This segmentation allows each layer to perform its specific function while collectively solving the reliability issue in miniaturized components.
Solution Approach 2:
The external electrode uses a composite structure combining different materials - primarily silver for electrical performance, combined with other metals (aluminum, copper, or their alloys) that provide mechanical strength and resistance to peeling. This composite approach maintains electrical conductivity while preventing the harmful effects of residual stress in compact designs.
2Reliability
If silver is exposed due to peeling, then the electrical connection is maintained, but migration risk increases
Solution Approach 1:
An intermediary protective layer (aluminum, copper, or their alloys) is introduced between the silver primary electrode layer and the external environment. This intermediary layer maintains electrical connection continuity while preventing direct exposure of silver, thereby eliminating the migration risk without compromising electrical reliability.
3Speed
If operating frequency is increased, then device performance is improved, but capacitance variation increases
Solution Approach 1:
The electrode structure parameters are optimized by controlling the thickness and composition of the protective layer relative to the primary silver layer. This parameter optimization ensures stable capacitance characteristics across high frequency ranges while maintaining good electrical conductivity and preventing migration, thus enabling high-performance operation with stable capacitance.
Data Source
AI summary
A multilayer ceramic component according to the present disclosure includes a sintered body, a plurality of internal electrodes, and a side surface electrode. The side surface electrode includes: a primary electrode layer containing silver as a main component thereof; and a plating layer covering the primary electrode layer at least partially. The primary electrode layer includes a first terminal portion provided for the side surface of the sintered body and a second terminal portion. The second terminal portion extends, in a second direction, from at least one of a pair of end portions of the first terminal portion in a third direction and is provided for at least one of a pair of principal surfaces. An interposed portion is formed by allowing a part of the plating layer to enter a region where a tip of the second terminal portion and the sintered body are separate from each other.