Multilayer Capacitor Internal Electrode Shrinkage Control
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Solution Overview
Problem
The miniaturization of multilayer capacitors requires internal electrodes with reduced thickness, but using finer metal powder particles leads to increased shrinkage initiation temperature differences between the electrode and ceramic layers, causing lumping and breakage phenomena during the sintering process.
Innovation Solution
The multilayer capacitor design includes internal electrodes with Ni grains, ceramics, and coating layers to suppress these issues, where the ceramics have poor wettability with Ni, and the coating layers are made of metals with lower melting points than Ni, ensuring connectivity and reduced thickness deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If finer metal powder particles are used to reduce internal electrode thickness, then the internal electrode thickness is reduced, but the shrinkage initiation temperature difference between the internal electrode and ceramic layer increases, causing lumping and breakage phenomena
Solution Approach 1:
A glass component is introduced as an intermediary substance in the conductive paste formulation. This glass content (5-20 wt%) acts as a mediator that reduces the shrinkage initiation temperature difference between the fine metal powder particles and the ceramic layer, preventing lumping and breakage phenomena during the sintering process while enabling the use of finer particles for reduced electrode thickness
Solution Approach 2:
The chemical composition parameters of the conductive paste are modified by adding specific glass content (5-20 wt%) and controlling the ratio of metal powder to ceramic particles. This parameter change alters the thermal and shrinkage characteristics of the internal electrode, enabling it to maintain integrity during sintering even with reduced thickness
2Length of stationary object
If finer metal powder particles are used to reduce internal electrode thickness, then the internal electrode thickness is reduced, but the internal electrode lumping phenomenon intensifies during the shrinkage process
Solution Approach 1:
The glass component serves as a lubricating intermediary during the sintering process, reducing friction and stress concentration between fine metal powder particles. This prevents the particles from aggregating into lumps while maintaining the reduced thickness and uniform shape of the internal electrode
Solution Approach 2:
The viscosity and flow characteristics of the conductive paste are modified through glass content adjustment, enabling better particle distribution and more uniform shrinkage behavior during sintering, thereby preventing lumping and maintaining shape uniformity
3Length of stationary object
If finer metal powder particles are used to reduce internal electrode thickness, then the internal electrode thickness is reduced, but the internal electrode breakage phenomenon intensifies during the shrinkage process
Solution Approach 1:
The glass phase acts as a binding intermediary that creates strong interparticle bonds between fine metal powder particles during sintering. This enhances the overall strength and fracture resistance of the internal electrode, preventing breakage phenomena even though the electrode thickness is reduced
Solution Approach 2:
The conductive paste is formulated as a composite material containing fine metal powder particles, ceramic particles, and glass content. This composite structure combines the electrical conductivity of metal with the strength and thermal stability of glass-ceramic matrix, creating an internal electrode that is both thin and mechanically robust
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 achieves internal electrodes with reduced thickness deviations and excellent connectivity, enhancing capacitance while preventing internal electrode lumping and breakage, thus addressing the challenges of miniaturization and capacitance increase.
Implementation Method 1
The first and second coating layers may be made of a metal having a melting point lower than that of Ni
Implementation Method 2
the conductive paste may further include one or more materials selected from the group consisting of Ag, Au, Zn, Sn, In, Al, Bi, Sb, Ge, and Te, a content of the one or more materials being 0.5 to 4.0 wt %, based on a content of the conductive powder particles
Data Source
AI summary
A multilayer capacitor includes: a body including dielectric layers and internal electrodes alternately disposed therein; and external electrodes disposed on the body and connected to the internal electrodes, respectively. Each of the internal electrodes includes a Ni grain, ceramics distributed in the Ni grain, a first coating layer surrounding the Ni grain, and second coating layers surrounding the ceramics.