Multilayer Ceramic Electrode Structure for Compact Mounting Reliability
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Solution Overview
Problem
The reduction in size of housings for multilayer ceramic capacitors has made it difficult to ensure desired capacitance while maintaining connection reliability and mountability due to the thicknesses of the base electrode layer, Ni plating film, and Sn plating film, which do not contribute to capacitance formation.
Innovation Solution
A multilayer ceramic component with external electrodes that include a base film thicker than the inner and outer plating films, with specific thickness ratios to ensure connection reliability and mountability, even in reduced-size housings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thicknesses of the base electrode layer, Ni plating film, and Sn plating film are increased to ensure connection reliability and mountability, then the electrical conductivity and solderability are improved, but the overall size of the multilayer ceramic capacitor increases, making it difficult to mount in reduced-size housings
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness ratios of the base electrode layer, Ni plating film, and Sn plating film. Specifically, the base electrode layer thickness is set to 1.4-3.0 times the Ni plating film thickness and 1.4-3.0 times the Sn plating film thickness, while the Ni plating film thickness is 0.2-0.3 times the total external electrode thickness, and the Sn plating film thickness is 0.2-0.3 times the total external electrode thickness. This parameter optimization ensures sufficient connection reliability and solderability while minimizing the overall capacitor size for mounting in reduced-size housings
Solution Approach 2:
The patent applies local quality by assigning different thickness ratios to different layers of the external electrode structure based on their specific functions. The base electrode layer is given greater thickness (1.4-3.0 times) to ensure connection reliability with internal electrodes, while the plating films (Ni and Sn) are given smaller thicknesses (0.2-0.3 times each of total thickness) to provide sufficient solderability and protection without excessive size increase. This differentiated local thickness allocation resolves the contradiction between reliability and size
2Volume of moving object
If the inner layer portion is reduced in size to accommodate reduced-size housings, then the mountability is improved, but the capacitance value decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness ratios of external electrode layers to decouple the relationship between capacitor size and capacitance value. By setting the base electrode layer thickness to 1.4-3.0 times the plating film thicknesses and the plating films to 0.2-0.3 times the total external electrode thickness, the patent ensures that the external electrode dimensions do not unnecessarily constrain the internal electrode area available for capacitance formation, thereby enabling reduced-size housings while maintaining desired capacitance values
3Reliability
If the Ni plating film thickness is increased to prevent solder leaching, then the corrosion resistance is improved, but the overall external electrode thickness increases, impairing mountability to reduced-size housings
Solution Approach 1:
The patent applies parameter changes by setting the Ni plating film thickness to 0.2-0.3 times the total external electrode thickness, which provides sufficient corrosion resistance and solder leaching prevention while keeping the overall external electrode thickness minimized for mountability in reduced-size housings
Solution Approach 2:
The patent applies composite materials by using a multi-layer external electrode structure consisting of the base electrode layer, Ni plating film, and Sn plating film. This composite structure provides corrosion resistance through the Ni layer and solderability through the Sn layer, allowing each layer to be optimized for its specific function while maintaining overall compact dimensions
4Reliability
If the Sn plating film thickness is increased to ensure solder wettability, then the solderability is improved, but the overall external electrode thickness increases, impairing mountability to reduced-size housings
Solution Approach 1:
The patent applies parameter changes by setting the Sn plating film thickness to 0.2-0.3 times the total external electrode thickness, which provides sufficient solder wettability while keeping the overall external electrode thickness minimized for mountability in reduced-size housings
Data Source
AI summary
A multilayer ceramic component in which an external electrode has a thickness that does not inhibit ease of mounting. This multilayer ceramic component includes external electrodes. The external electrodes each include: a base film that extends to a first main surface and a second main surface and in contact with the internal electrode layers; an inner plating film in contact with the base film; and an outer plating film in contact with the inner plating film. The base film has a thickness that is 1.4 to 3.0 times the film thickness of the inner plating film and is 1.4 to 3.0 times the film thickness of the outer plating film. The film thickness of the base film is 0.4 to 0.6 times the total film thickness of the base film, the inner plating film and the outer plating film.