Electronic Component Firing Process Oxygen Control
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Solution Overview
Problem
Existing methods for producing ferrite elements with internal conductors face challenges in achieving favorable electrical characteristics due to abnormal grain growth and inadequate coexistence of Cu and Fe2O3 at high temperatures, leading to reduced specific resistance and reliability issues.
Innovation Solution
A method involving a firing step in an atmosphere with an oxygen concentration equal to or lower than the equilibrium oxygen partial pressure of Cu—Cu2O, followed by an oxygenic-atmosphere heat treatment to oxidize the magnetic body part, while preventing oxidation of the internal conductor, ensuring the magnetic body's original characteristics and inhibiting Cu oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If firing is carried out in a nitrogen atmosphere with low-melting-point constituents to reduce firing temperature, then the firing temperature can be reduced to 950-1030°C, but the Cu internal conductor oxidizes and the magnetic body characteristics deteriorate
Solution Approach 1:
The patent divides the heat treatment process into two distinct stages: (1) firing in a nitrogen atmosphere at 950-1030°C to sinter the ferrite matrix, and (2) subsequent heat treatment in an oxidizing atmosphere at 500-800°C to restore magnetic body characteristics. This segmentation allows each stage to optimize for its specific purpose without compromising the other.
Solution Approach 2:
The patent performs preliminary oxidation of the Cu internal conductor surface during the firing stage in nitrogen atmosphere, creating a protective oxide layer before the main sintering process. This preliminary action prevents excessive oxidation during subsequent processing while maintaining electrical conductivity.
2Loss of energy
If the magnetic body is reduced during firing to lower the firing temperature, then energy consumption is reduced, but the magnetic body loses its original characteristics and requires additional oxidation treatment
Solution Approach 1:
The patent employs periodic action by alternating between reducing atmosphere (nitrogen) during firing to reduce energy consumption and oxidizing atmosphere during subsequent heat treatment to restore magnetic body characteristics. This periodic switching of atmospheric conditions allows the system to achieve both energy efficiency and compositional stability.
3Productivity
If Cu and Fe2O3 are maintained at high temperatures together, then the internal conductor and magnetic body can be fired simultaneously, but abnormal grain growth occurs and specific resistance decreases
Solution Approach 1:
The patent changes the temperature parameter from high temperature (above 1000°C) to a lower range of 950-1030°C, and changes the atmospheric parameter from oxidizing to reducing (nitrogen atmosphere) during firing. These parameter changes prevent abnormal grain growth and maintain appropriate specific resistance while still achieving simultaneous firing of the internal conductor and magnetic body.
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 approach results in a highly reliable electronic component with improved impedance and specific resistance values, achieving desired electrical characteristics by maintaining the magnetic body's oxidation state and preventing internal conductor oxidation.
Implementation Method 1
an oxygenic-atmosphere heat treatment step of subjecting a fired laminated body obtained by the firing in the firing step to a heat treatment in an atmosphere with an oxygen concentration of 0.01% or more in a subsequent temperature decrease process
Implementation Method 2
a firing step of firing an unfired laminated body in an atmosphere with an oxygen concentration equal to or lower than an equilibrium oxygen partial pressure of Cu—Cu2O
Data Source
AI summary
The disclosure provides a method for producing an electronic component in which the oxidation of Cu constituting an internal conductor part of the component is inhibited or prevented in a firing step, and even when a magnetic body part containing NiO, ZnO, Fe2O3, etc. is reduced in the firing step, the magnetic body part is subsequently oxidized to ensure the original characteristics. In producing the electronic component, an unfired laminated body including parts to serve as the magnetic body part and the internal conductor part after firing is subjected to firing in an atmosphere with an oxygen concentration equal to or lower than the equilibrium oxygen partial pressure of Cu—Cu2O, and the fired laminated body is then subjected to an oxygenic-atmosphere heat treatment in an atmosphere with an oxygen concentration of 0.01% or more in a step of decreasing the temperature.