MLCC External Electrode Plating With Sn Interlayer Uniformity
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Solution Overview
Problem
Conventional multilayer ceramic capacitors face issues with uneven plating films during electrolytic plating, leading to solder erosion and inconsistent thickness, which affects the reliability and capacitance of the capacitors.
Innovation Solution
A multilayer ceramic capacitor design featuring a base electrode layer with a Sn-deposited region between the Ni and Sn plated layers, ensuring a smooth deposition and growth of the plating film, thereby providing a reliable and uniform plated layer coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick plating film is formed to improve film-forming property, then the plated layer coverage is improved, but the thickness of the ceramic element body must be reduced to maintain standard dimensions, resulting in decreased capacitance
Solution Approach 1:
A Sn-deposited region is formed on the base electrode layer before applying the Ni and Sn plated layers. This preliminary deposition creates a foundation that improves subsequent plating film formation, allowing for reliable plated layer coverage without requiring excessive plating thickness that would reduce ceramic body dimensions and capacitance.
2Productivity
If electrolytic plating is used to form the plated layer, then the plating process is efficient, but uneven deposition occurs leading to solder erosion and inconsistent thickness
Solution Approach 1:
The Sn-deposited region is prepared in advance on the base electrode layer to create a uniform foundation. This preliminary action ensures that subsequent electrolytic plating deposits Ni and Sn layers evenly, preventing solder erosion and maintaining consistent thickness throughout the plated layer.
Solution Approach 2:
The Sn-deposited region acts as an intermediary layer between the base electrode layer and the Ni/Sn plated layers. This intermediate layer facilitates uniform electrolytic plating deposition, ensuring consistent thickness and preventing the uneven deposition that would otherwise occur during the electrolytic plating process.
3Productivity
If the current in electrolytic plating is increased to form a thick plating film faster, then the plating speed is improved, but variations in plated layer thickness increase making quality control difficult
Solution Approach 1:
The Sn-deposited region is formed beforehand to provide a uniform base for electrolytic plating. This preliminary preparation allows for faster plating speeds with increased current while maintaining consistent thickness, as the Sn-deposited region ensures uniform current distribution and deposition throughout the plating process.
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
This design enhances the reliability of the plated layer coverage on the base electrode, preventing solder erosion and maintaining consistent capacitance, even in mass production, by stabilizing the Sn/Ni molar ratio in the deposited region.
Implementation Method 1
deposition and growth of a plating film smoothly proceed by providing a region in which Sn is deposited on a surface of a base electrode layer
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including dielectric layers and internal electrode layers alternately laminated, and external electrodes each on a corresponding one of two end surfaces opposed to each other in a length direction perpendicular or substantially perpendicular to a lamination direction of the multilayer body. The external electrodes are each connected to the internal electrode layers. Each of the external electrodes includes a stack including a base electrode layer on a corresponding one of the two end surfaces, a Ni plated layer on the base electrode layer, and a Sn plated layer on the Ni plated layer. Each of the external electrodes includes a region in which Sn is deposited between the base electrode layer and the Ni plated layer.