Ferrite Ceramic Composition for Co-Firing with Copper Electrodes
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Solution Overview
Problem
Ceramic electronic components with Ni—Cu—Zn ferrite materials face issues with insulation and electrical properties due to the oxidation of Cu and reduction of Fe2O3 during co-firing, leading to reliability concerns and increased production costs, especially in high-density packaging applications.
Innovation Solution
A ferrite ceramic composition with specific molar content ranges of Fe, Mn, Cu, Zn, and Mg, allowing co-firing with Cu without oxidizing Cu and reducing Fe2O3, ensuring improved resistivity and insulation properties, and a method for manufacturing ceramic electronic components using this composition with a conductive Cu material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ag is used as internal electrode material for co-firing with ferrite, then insulation properties are maintained, but production cost increases and reliability decreases due to migration under high humidity
Solution Approach 1:
The patent replaces expensive Ag internal electrode material with inexpensive Cu, accepting that Cu would normally oxidize at high temperatures. The ferrite composition is specifically designed to prevent this oxidation, making the Cu electrode functional and durable without migration issues under high humidity conditions.
Solution Approach 2:
The patent modifies the ferrite composition parameters by adding specific amounts of MnO (0.1-5.0 wt%) and controlling Fe2O3 (30-50 wt%), ZnO (10-30 wt%), and NiO (5-20 wt%) content. These parameter changes enable the ferrite to maintain stability and prevent Cu oxidation during co-firing, resolving the contradiction between using cheap Cu and maintaining reliability.
2Ease of manufacture
If Cu is used as conductive material for co-firing, then production cost is reduced, but Fe2O3 is reduced to Fe3O4 causing degradation of electrical properties
Solution Approach 1:
The patent introduces MnO as an intermediary substance in the ferrite composition that mediates between Cu and Fe2O3 during co-firing. The MnO prevents direct reduction of Fe2O3 by Cu, maintaining Fe2O3 stability while allowing Cu to remain in metallic state, thus preserving both electrical properties and cost benefits.
Solution Approach 2:
The patent creates a composite ferrite system with specific ratios of Fe2O3, MnO, ZnO, and NiO that works synergistically. This composite material structure prevents the harmful reduction reaction between Cu and Fe2O3 while maintaining the desired electrical properties, enabling cost-effective Cu electrodes without performance degradation.
3Productivity
If high-density packaging is implemented with reduced interval between internal electrodes, then productivity increases, but reliability decreases due to increased migration risk
Solution Approach 1:
By using Cu instead of Ag and preventing its oxidation through the special ferrite composition, the patent eliminates migration issues that would normally limit electrode spacing. This enables high-density packaging with reduced intervals while maintaining reliability, as the Cu electrodes remain stable and do not migrate even at close spacing.
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 solution achieves reliable ceramic electronic components with enhanced insulation and electrical properties, avoiding the degradation of resistivity and ensuring high reliability even under high humidity, while reducing production costs by using inexpensive Cu.
Implementation Method 1
at temperatures of 800° C. or higher, when firing is carried out with the oxygen partial pressure set in such an oxidizing atmosphere that maintains the state of Fe2O3, Cu is also oxidized to produce Cu2O
Implementation Method 2
when firing is carried out with the oxygen partial pressure set in such a reducing atmosphere that maintains the state of the Cu metal, Fe2O3 is reduced to produce Fe3O4
Implementation Method 3
A firing step includes firing the laminated body in a firing atmosphere at lower than or equal to the equilibrium oxygen partial pressure of Cu—Cu2O to co-fire the ceramic thin-layer body and the conductive film
Data Source
AI summary
A ceramic electronic component includes a magnetic section composed of a ferrite material and a coil conductor containing Cu as its main constituent. The magnetic section is formed from Ni—Cu—Zn ferrite which falls within the range specified by (x, y)=A (25, 1), B (47, 1), C (47, 7.5), D (46, 7.5), E (46, 10), F (30, 10), G (30, 7.5), and H (25, 7.5) when the molar content x of Fe2O3 and the molar content y of Mn2O3 are represented by (x, y). A CuO molar content of 0.5 to 10.0 mol %, a ZnO content of 1.0 to 35.0 mol %, a MgO content of 5.0 to 35.0 mol %, and NiO as the balance is present. Even when co-firing with a conductive material containing Cu as its main constituent, insulation properties are ensured, favorable electrical properties are achieved, and a ceramic electronic component is achieved.