MLCC External Electrode Composition to Prevent Reflow Delamination
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Solution Overview
Problem
Multilayer ceramic capacitors face issues with delamination at the interface between the sintered electrode layer and the conductive resin layer due to outgas during high-temperature reflow, and excessive tin in the conductive resin layer can degrade plating characteristics and reduce electrical connectivity.
Innovation Solution
A multilayer electronic component design featuring a second electrode layer with a conductive portion comprising an silver (Ag)-tin (Sn) alloy and an intermetallic compound, where the ratio of the Ag—Sn alloy area to the conductive portion area is between 3 to 50%, ensuring improved bonding and preventing delamination and tin elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the conductive resin layer includes more content of Ag3Sn to improve electrical and mechanical bonding, then bonding strength is improved, but excessive tin (Sn) is eluted to the surface of the external electrode, degrading plating characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the conductive resin layer by specifying precise ranges: Ag3Sn content at 60-80 wt%, additional Sn content controlled at 5-20 wt%, and Cu content at 5-20 wt%. This parameter optimization ensures sufficient bonding strength while preventing excessive Sn elution that would degrade plating characteristics.
Solution Approach 2:
The patent creates a composite conductive resin layer combining multiple materials with complementary functions: Ag3Sn provides primary bonding strength, controlled Sn content enhances conductivity and bonding, while Cu content prevents excessive Sn elution. The resin matrix binds these components together, creating a composite structure that balances bonding strength and plating quality.
2Strength
If the conductive resin layer is ref lowed at a high temperature to improve bonding, then mechanical bonding is enhanced, but delamination occurs at the interface due to outgas generated from the conductive resin layer
Solution Approach 1:
The patent optimizes the resin component parameters by selecting specific resin types (epoxy, phenolic, or polyester) and controlling resin content at 20-40 wt%. This parameter control reduces excessive outgas generation during reflow while maintaining adequate bonding strength, preventing delamination at the interface.
Solution Approach 2:
The patent creates different functional zones within the conductive resin layer: the Ag3Sn and Sn particles provide local bonding strength at the sintered electrode layer interface, while the Cu content specifically addresses outgas-related delamination issues. The resin matrix provides local adhesion throughout the layer, creating localized quality improvements that prevent interface delamination.
3Reliability
If conductive metal particles are dispersed in the conductive resin layer to provide conductivity, then electrical connection is established, but the electrical conductivity becomes weak
Solution Approach 1:
The patent creates a composite conductive network using multiple metal particle types with different properties: Ag3Sn particles provide primary conductivity pathways, additional Sn particles enhance electrical connection, and Cu particles contribute to conductivity while controlling Sn elution. This multi-component composite structure achieves strong electrical connection without relying on excessive particle dispersion.
Solution Approach 2:
The patent creates localized conductive clusters where Ag3Sn, Sn, and Cu particles are strategically distributed within the resin matrix. These local conductive zones provide efficient electrical pathways through the conductive resin layer, achieving strong overall electrical connection through distributed local quality improvements rather than uniform dispersion.
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
The design enhances mechanical and electrical connections, suppresses delamination during high-temperature reflow, and maintains optimal plating characteristics by controlling the distribution of the Ag—Sn alloy and intermetallic compounds.
Implementation Method 1
an intermetallic compound formed by diffusion between a silver (Ag) and a tin (Sn)
Implementation Method 2
an intermetallic compound formed by diffusion between a silver (Ag) and a tin (Sn)
Implementation Method 3
coating a conductive resin layer on an external electrode thereof to absorb tensile stress occurring in a mechanical or thermal environment
Implementation Method 4
This conductive resin layer may electrically and mechanically bond the sintered electrode layer and plating layer of the external electrode of the multilayer capacitor to each other
Data Source
AI summary
A multilayer electronic component includes: a body including a dielectric layer and a plurality of internal electrodes stacked on each other interposing the dielectric layer therebetween, and external electrodes respectively disposed on the body, wherein the external electrode includes: a first electrode layer connected to the internal electrode; and a second electrode layer disposed on the first electrode layer, and including a conductive portion including an silver (Ag)-tin (Sn) alloy and a resin, and a ratio of an area of the Ag—Sn alloy to an area of the conductive portion satisfies 3 to 50% in at least a portion of a cross-section of the second electrode layer.