Multilayer Ceramic Capacitor Interface Layer Against Plating Infiltration
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face challenges in achieving sufficient moisture resistance, which is crucial for improving their reliability.
Innovation Solution
The capacitors incorporate a multilayer body with dielectric ceramic and internal electrode layers, featuring external electrodes with a Ni-based first layer, a Cu-based second layer, and a plated layer, along with an interface region containing metals like Sn, In, Ga, Zn, Bi, Pb, Fe, V, or Cu, which enhances moisture resistance by preventing the infiltration of plating solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an intermediate layer containing Ni, Cu or Ni-Cu alloy is provided under the plated layer, then penetration of plating solution is prevented, but moisture resistance is insufficient
Solution Approach 1:
The external electrode is divided into three distinct layers: a Ni-based first external electrode layer, a Cu-based second external electrode layer, and a plated layer. This segmentation allows each layer to perform its specific function - the Ni layer provides moisture barrier, the Cu layer provides conductivity, and the plated layer provides corrosion resistance
Solution Approach 2:
The external electrode uses a composite structure combining Ni, Cu, and plated materials. The Ni-Cu alloy particles in the first external electrode layer create a composite material that provides both moisture resistance and electrical conductivity, while the glass particles add sealing properties
2Ease of manufacture
If a simple plated layer is used on the external electrode, then manufacturing is simple, but moisture and plating solution infiltration occurs
Solution Approach 1:
Instead of a single plated layer, the external electrode is segmented into multiple functional layers. The first external electrode layer (Ni-based) serves as a moisture barrier, the second external electrode layer (Cu-based) provides conductivity, and the plated layer provides corrosion protection
Solution Approach 2:
The first external electrode layer uses a composite of Ni particles, Ni-Cu alloy particles, and glass particles. This composite structure provides both moisture resistance and electrical conductivity, which a simple plated layer cannot achieve
3Reliability
If external electrodes are made with moisture-resistant materials, then reliability improves, but plating solution penetration occurs
Solution Approach 1:
The external electrode is segmented into distinct layers where the Ni-based first layer handles moisture resistance, the Cu-based second layer handles conductivity, and the plated layer handles plating solution resistance. This segmentation allows each material to optimize for its specific function
Solution Approach 2:
The first external electrode layer uses a composite of Ni, Ni-Cu alloy, and glass particles that provides both moisture resistance and resistance to plating solution penetration, while maintaining electrical conductivity through the Ni-Cu alloy component
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body and a pair of external electrodes at both ends of the multilayer body in a length direction and covering a pair of end surfaces, and connected to internal electrode layers. The pair of external electrodes each include a first external electrode layer covering each of the end surfaces and connected to the internal electrode layers, a second external electrode layer on the first external electrode layer, and a plated layer on the second external electrode layer, the first external electrode layer includes Ni and dielectric particles, the second external electrode layer includes Cu and glass, and a metal group including at least one of Sn, In, Ga, Zn, Bi, Pb, Fe, V, Y, or Cu is included at an interface between the first and second external electrode layers.