MLCC External Electrode Resin for Bending Strength and Plating
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Solution Overview
Problem
Multilayer ceramic capacitors face issues with insufficient bending strength and improper formation of plating layers on external electrodes, leading to moisture penetration and reduced reliability.
Innovation Solution
The multilayer ceramic capacitor design includes external electrodes with conductive resin layers made of tin and bismuth, along with intermetallic compounds like Cu6Sn5, Cu3Sn, and Ag3Sn, and a well-formed plating layer of nickel and tin, enhancing mechanical and electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional external electrodes are used without optimized conductive resin layers, then the structure is simpler, but bending strength is insufficient and plating layers do not form properly
Solution Approach 1:
The external electrode uses a composite conductive resin layer containing tin powder, bismuth powder, and glass powder in specific ratios. This composite formulation enhances bending strength while providing proper substrate for plating layer formation, resolving the contradiction between strength improvement and structural complexity
Solution Approach 2:
The conductive resin layer optimizes particle size distribution (D50: tin 5-10 μm, bismuth 3-7 μm, glass 2-5 μm) and compositional parameters (tin 70-90 wt%, bismuth 5-20 wt%, glass 1-10 wt%). These parameter optimizations improve bending strength and plating formation without requiring complex multi-layer structures
2Reliability
If plating layers are applied on external electrodes with insufficient bending strength, then electrical connectivity is achieved, but moisture penetration occurs and reliability deteriorates
Solution Approach 1:
The conductive resin layer is designed beforehand to provide sufficient bending strength and proper surface properties before plating application. This pre-prepared foundation prevents moisture penetration pathways from forming, protecting the underlying structure and maintaining reliability
Solution Approach 2:
The conductive resin layer acts as an intermediary between the external electrode substrate and the plating layer. It provides mechanical strength support and creates an optimal surface for plating adhesion, preventing moisture from reaching and damaging the internal structure
3Manufacturing precision
If conductive resin layers with optimized tin and bismuth content are used, then bending strength and plating layer formation improve, but manufacturing process becomes more complex
Solution Approach 1:
The invention specifies precise compositional parameters (tin 70-90 wt%, bismuth 5-20 wt%, glass 1-10 wt%) and particle size parameters (D50 values) for the conductive resin layer. These optimized parameters ensure consistent plating layer formation quality while maintaining a relatively simple single-layer manufacturing 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 improves bending strength and moisture resistance, reducing plating breakage and maintaining electrical performance, as evidenced by lower equivalent series resistance and consistent insulation resistance.
Implementation Method 1
the first conductive resin layer and the second conductive resin layer include tin (Sn) and bismuth (Bi)... The first conductive connection portion may include tin (Sn) in an amount of 36 wt % or more and 50.4 wt % or less, and bismuth (Bi) in an amount of 14 wt % or more and 19.6 wt % or less
Implementation Method 2
The intermetallic compound included in the first conductive resin layer and the intermetallic compound included in the second conductive resin layer may include at least one of Cu6Sn5, Cu3Sn, Ni3Sn, and Ag3Sn
Implementation Method 3
a well-formed plating layer of nickel and tin
Implementation Method 4
a first plating layer covering the first external electrode and a second plating layer covering the second external electrode
Data Source
AI summary
A multilayer ceramic capacitor includes a ceramic body including a plurality of first internal electrodes and a plurality of second internal electrodes disposed inside the ceramic body, and a first external electrode and a second external electrode disposed outside the ceramic body. The first external electrode includes a first end portion electrically connected to the plurality of first internal electrodes, a first side portion extending from the first end portion, and a first conductive resin layer covering at least a portion of the first side portion, and the second external electrode includes a second end portion electrically connected to the plurality of second internal electrodes, a second side portion extending from the second end portion, and a second conductive resin layer covering at least a portion of the second side portion, and wherein the first conductive resin layer and the second conductive resin layer include tin (Sn) and bismuth (Bi).