Multilayer Ceramic Capacitor External Electrode Moisture and Crack Resistance
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Solution Overview
Problem
Electronic components with external electrodes on laminates are prone to cracking under bending stress, leading to moisture intrusion and reduced insulation resistance, as existing resin-based external electrodes are permeable and fail to effectively prevent moisture ingress.
Innovation Solution
A multilayer ceramic capacitor design featuring a Ni layer, a Ni—Sn alloy layer, and a resin layer with metal grains on the external electrode, where the Ni and Ni—Sn alloy layers are sintered with internal electrodes and the resin layer is heat-treated to form a durable external electrode that reduces moisture intrusion and crack generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an external electrode is formed using a resin including metal grains, then resistance to bending stress is improved, but moisture intrusion occurs through the resin
Solution Approach 1:
The patent employs a composite external electrode structure consisting of a resin layer containing metal grains (for flexibility and stress resistance) combined with a moisture barrier layer (for moisture protection). This composite approach allows the electrode to simultaneously achieve bending stress resistance through the resin's flexibility and moisture intrusion prevention through the barrier layer's impermeability.
Solution Approach 2:
The external electrode is divided into multiple functional layers: a resin layer with metal grains that provides mechanical flexibility and stress resistance, and a separate moisture barrier layer that prevents moisture intrusion. This segmentation allows each layer to perform its specific function optimally without compromising the other.
2Reliability
If a resin layer is used in the external electrode, then crack generation under bending stress is reduced, but insulation resistance decreases due to moisture permeation
Solution Approach 1:
The patent combines a resin layer (which provides crack resistance and flexibility) with a moisture barrier layer (which prevents moisture permeation that would reduce insulation resistance). This composite structure allows the electrode to maintain both mechanical reliability under bending stress and electrical insulation properties.
Solution Approach 2:
The moisture barrier layer acts as an intermediary between the resin layer and the internal electrode, preventing moisture from reaching the internal electrode while allowing the resin layer to provide its crack-resistant function. This intermediary layer resolves the conflict between mechanical flexibility and electrical insulation.
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 significantly enhances the resistance to bending stress and prevents moisture intrusion, maintaining insulation resistance and reducing the likelihood of internal electrode short-circuits by using a Ni—Sn alloy and resin layer configuration.
Implementation Method 1
integrally firing the Ni-containing conductive paste and the unfired laminate to form the laminate having a Ni layer formed on an end surface
Implementation Method 2
heat-treating the laminate coated with the resin paste to form a Ni—Sn alloy layer on the Ni layer
Implementation Method 3
heat-treating the laminate coated with the resin paste to form a Ni—Sn alloy layer on the Ni layer
Data Source
AI summary
An electronic component includes a laminate and an external electrode provided on an end surface of the laminate. The external electrode includes a Ni layer provided on the end surface, a Ni—Sn alloy layer provided on the Ni layer, and a resin layer that is provided on the Ni—Sn alloy layer and includes metal grains including Sn grains. The Ni layer and the Ni—Sn alloy layer reduce or prevent intrusion of moisture from the external electrode into an interior of the laminate, and the resin layer reduces or prevents generation of cracks when a bending stress is applied to the external electrode.