Multilayer Capacitor Electrode Plating for Stress Relief and Crack Suppression
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Solution Overview
Problem
Multilayered capacitors face issues with stress relief, leading to cracking and deterioration of electrical characteristics due to the introduction of a conductive resin layer, which also increases equivalent series resistance (ESR) and susceptibility to moisture absorption and metal oxidation.
Innovation Solution
A multilayered capacitor design with a sintered metal layer, conductive resin layer, and plating layer, where the plating layer thickness is optimized to minimize the conductive resin volume, reducing stress while maintaining electrical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conductive resin layer is introduced into the external electrode to relieve stress, then stress relief is improved, but equivalent series resistance (ESR) deteriorates and moisture absorption increases
Solution Approach 1:
The patent applies local quality by creating a plating layer with different thicknesses in different regions: a first thickness in the first region and a second thickness (0.2×Te1≤Te2≤0.8×Te1) in the second region. This non-uniform plating structure provides localized stress relief where needed while maintaining electrical performance in other areas, thus resolving the contradiction between stress relief and electrical characteristics.
2Strength
If the conductive resin layer volume is increased to enhance stress relief, then stress relief is improved, but crack generation and burst defects increase
Solution Approach 1:
The patent implements local quality by positioning the conductive resin layer specifically in the second region and controlling its thickness through the plating layer configuration. This localized approach provides stress relief precisely where needed while minimizing the overall resin volume, thereby preventing crack generation and burst defects that would occur with excessive resin throughout the entire electrode.
3Strength
If the conductive resin layer is introduced to relieve stress, then stress relief is improved, but lifting and bursting defects occur due to moisture absorption and metal oxidation
Solution Approach 1:
The patent introduces the plating layer as an intermediary between the sintered metal layer and the conductive resin layer. This plating layer acts as a protective barrier that prevents moisture absorption and metal oxidation, thereby eliminating lifting and bursting defects while maintaining the stress relief function of the conductive resin layer.
4Object-affected harmful factors
If the plating layer thickness is increased to protect against moisture and oxidation, then protection is improved, but stress relief capability deteriorates
Solution Approach 1:
The patent applies local quality by varying the plating layer thickness across different regions: a first thickness in the first region for protection, and a controlled second thickness (0.2×Te1≤Te2≤0.8×Te1) in the second region where the conductive resin layer is present. This regional differentiation maintains protection against moisture and oxidation while preserving stress relief capability.
Data Source
AI summary
A multilayered capacitor includes a capacitor body including a dielectric layer and an internal electrode, and an external electrode disposed on the capacitor body. The external electrode includes a first region including a portion of a sintered metal layer and a portion of a plating layer and a second region including another portion of the sintered metal layer, a conductive resin layer, and another portion of the plating layer. An average thickness Te1 of the plating layer in the first region and an average thickness Te2 of the plating layer in the second region satisfy 0.2×Te1<Te2≤0.8×Te1.