Multilayer Ceramic Capacitor Alkali Ion Migration Barrier
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability issues due to increased electrostatic capacitance when operating at high voltages and temperatures, as alkali metal ions migrate, causing copper ions to deposit and extend the internal electrode layer, exceeding standard capacitance limits.
Innovation Solution
A manufacturing method involving a ceramic multilayer body with a perovskite dielectric layer composed of CaZrO3 and an internal electrode layer made of copper with a co-material containing CaZrO3, but no alkali metal, which forms a barrier to inhibit alkali metal ion migration during high voltage applications, preventing copper ion deposition and capacitance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer ceramic capacitor uses a dielectric layer containing alkali metal and copper internal electrode, then the capacitor achieves basic electrical function, but alkali metal ions migrate at high voltage and temperature causing capacitance increase and reliability degradation
Solution Approach 1:
The patent introduces a barrier layer composed of calcium zirconate ceramic material between the copper internal electrode and the alkali metal-containing dielectric layer. This intermediary barrier layer prevents direct interaction between copper ions and alkali metal ions, blocking the migration path that would otherwise lead to capacitance increase and reliability degradation.
Solution Approach 2:
The patent employs a composite structure combining calcium zirconate ceramic material with specific crystal structure to create a barrier layer that exhibits both electrical insulation properties and chemical stability. This composite approach leverages the beneficial properties of calcium zirconate to simultaneously resist alkali metal ion migration and maintain capacitor performance under high voltage and temperature conditions.
2Power
If the capacitor operates at high voltage and temperature, then the electrical performance is maintained, but copper ions deposit and extend the internal electrode layer causing capacitance increase
Solution Approach 1:
The calcium zirconate barrier layer serves as a protective intermediary that prevents copper ions from migrating and depositing on the dielectric layer during high voltage operation. This barrier maintains the dimensional integrity of the internal electrode layer even under elevated power conditions, preventing capacitance drift.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the interface between the internal electrode and dielectric layer by introducing the calcium zirconate barrier. This changes the electrochemical stability of the interface, preventing copper ion dissolution and deposition reactions that would otherwise occur at high voltage, thereby maintaining precise electrode dimensions.
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 method effectively inhibits capacitance increase, ensuring the multilayer ceramic capacitor operates within specified reliability standards even under high temperature and voltage conditions, maintaining reliability and performance.
Implementation Method 1
a ceramic material having a perovskite structure that includes Ca and Zr and is expressed by a general expression ABO3... containing an alkali metal... a conductive paste being mainly composed of Cu, containing a ceramic co-material and no alkali metal
Data Source
AI summary
A method of manufacturing a multilayer ceramic capacitor includes: forming a multilayer body by alternately stacking a green sheet and a conductive paste for forming an internal electrode layer, the green sheet being mainly composed of a ceramic material having a perovskite structure that includes Ca and Zr and is expressed by a general expression ABO3 and containing an alkali metal, the conductive paste being mainly composed of Cu, containing a ceramic co-material and no alkali metal; and baking the multilayer body to obtain a ceramic multilayer body.