MLCC Base Electrode Thickness Profile for Cu Plating Adhesion
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Solution Overview
Problem
The adhesion between the base electrode layer and the Cu-plated layer in multilayer ceramic capacitors decreases when the base electrode layer is subjected to barrel processing, resulting in a smoother surface that compromises adhesion.
Innovation Solution
The multilayer ceramic capacitor design includes a base electrode layer with an outer peripheral surface portion that has a specific thickness profile, consisting of three portions (t1, t2, t3) in order from the end surface toward the center, where t1 > t2 > t3, to enhance adhesion with the Cu-plated layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the base electrode layer is subjected to barrel processing to smooth the surface, then the surface smoothness is improved, but the adhesion between the base electrode layer and the Cu-plated layer deteriorates
Solution Approach 1:
The base electrode layer is designed with non-uniform thickness, featuring a thicker outer peripheral portion and a thinner central portion. This local variation in thickness creates different surface characteristics: the outer peripheral portion maintains sufficient roughness for strong adhesion after barrel processing, while the central portion achieves the desired smoothness. This resolves the contradiction by applying different surface quality requirements to different regions of the base electrode layer.
2Reliability
If the base electrode layer thickness is increased to improve adhesion, then the adhesion is improved, but the manufacturing complexity and material usage increase
Solution Approach 1:
Instead of uniformly increasing the base electrode layer thickness throughout, the invention applies increased thickness only to the outer peripheral portion where adhesion is critical. The central portion maintains a thinner profile, reducing overall material usage and manufacturing complexity while still achieving the required adhesion performance in the critical outer regions.
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including internal electrode layers and internal dielectric layers alternatively laminated therein, main surfaces on both sides in a lamination direction, end surfaces on both sides in a length direction intersecting the lamination direction, and lateral surfaces on both sides in a width direction intersecting the lamination direction and the length direction, and two external electrodes on the end surfaces of the multilayer body and including base electrode layers. The base electrode layers include an end surface portion on the end surface, and an outer peripheral portion on the main surface and the lateral surface, and the outer peripheral surface portion includes first, second, and third portions respectively having thicknesses t1, t2, and t3 in this order from the end surface toward a center in the length direction, and the relationship of t1>t2>t3 is satisfied.