Dielectric Ceramic Composition for Low Temperature Sintering
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Solution Overview
Problem
Current dielectric ceramic materials for high-frequency electronic devices have high specific permittivity, leading to limitations in responding to high frequencies, and require high sintering temperatures, making it challenging to achieve low temperature sintering and compatibility with materials having varying coefficients of linear expansion.
Innovation Solution
A dielectric ceramic composition comprising Cu oxide, Si oxide, Mg oxide, and Zn oxide with a glass component including B oxide and other oxides, having a glass softening point of 750°C or less, which allows for low temperature sintering and adjustable coefficients of linear expansion, enabling cofiring with different materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric ceramic materials (Ni-Cu-Zn ferrite or Cu-Zn ferrite) are used, then magnetic properties are achieved, but specific permittivity is high (about 15), causing stray capacitance effects that limit high frequency response
Solution Approach 1:
The patent changes the fundamental material parameters by transitioning from ferrite-based magnetic materials to a dielectric ceramic system with specific oxide composition (CuO-SiO2-MgO-ZnO) and controlled glass content (5-20 wt%). This parameter change achieves specific permittivity below 10, eliminating stray capacitance effects while maintaining suitability for high frequency applications.
Solution Approach 2:
The patent employs a composite material system combining crystalline phases (forsterite Mg2SiO4 and willemite Zn2SiO4) with a glass phase containing B2O3 and other oxides. This composite structure achieves the desired low specific permittivity and high Q-value while enabling low temperature sintering and cofiring compatibility.
2Reliability
If high sintering temperature is used to achieve good material properties, then material performance is improved, but it becomes difficult to cofire with materials having different coefficients of linear expansion and increases manufacturing cost
Solution Approach 1:
The patent introduces glass components with softening points of 750°C or lower into the dielectric ceramic composition. This parameter change in the material composition enables sintering at temperatures of 950°C or lower, reducing manufacturing costs and enabling cofiring with materials having different thermal expansion characteristics.
Solution Approach 2:
The patent controls the coefficient of linear expansion of the dielectric ceramic to be within 10-50 ppm/°C by adjusting the oxide composition and glass content. This enables thermal expansion matching with other materials in the multilayer structure, facilitating successful cofiring at lower temperatures without causing delamination or cracking.
3Ease of manufacture
If glass content is increased to achieve low temperature sintering, then sintering temperature is reduced, but reliability decreases due to excessive glass component
Solution Approach 1:
The patent optimizes the glass content parameter to be within 5-20 wt% of the total composition. This controlled parameter range provides sufficient glass phase to enable low temperature sintering (950°C or lower) while maintaining adequate structural integrity and reliability by preventing excessive glassy phase that would compromise mechanical and electrical properties.
Solution Approach 2:
The patent creates a heterogeneous microstructure where the glass phase is distributed locally among the crystalline forsterite and willemite phases. This local distribution of glass provides sintering aid at grain boundaries and pores while maintaining the structural framework of the crystalline phases, achieving both low temperature processing and high reliability.
4Reliability
If Ag is used as conducting material to reduce cost and DC resistance, then electrical performance is improved, but it requires sintering temperature below Ag softening point (950°C or lower)
Solution Approach 1:
The patent modifies the dielectric ceramic composition by incorporating glass components with softening points of 750°C or lower, enabling sintering at temperatures of 950°C or lower. This parameter change in processing temperature allows the use of Ag as conducting material without exceeding its softening point, achieving low DC resistance while maintaining manufacturing feasibility.
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 composition achieves low specific permittivity, high f·Q-value, and high insulation resistance while allowing for low temperature sintering and compatibility with various materials, enhancing the performance and reliability of multilayer electronic devices.
Implementation Method 1
a dielectric ceramic composition which comprises as a main component Cu oxide, Si oxide, Mg oxide and Zn oxide, as a subcomponent a glass component including B oxide and at least one selected from Si oxide, Ba oxide, Ca oxide, Sr oxide, Li oxide and Zn oxide, and having a glass softening point of 750°C or less
Data Source
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AI summary
A dielectric ceramic composition comprises as a main component, Cu oxide, Si oxide and one selected from the group consisting of Zn oxide alone and a combination of Mg oxide and Zn oxide, as a subcomponent, a glass component including B oxide and at least one selected from the group consisting of Si oxide, Ba oxide, Ca oxide, Sr oxide, Li oxide and Zn oxide, and having a glass softening point is 750°C or less, wherein a content of said glass component is 1.5 to 15wt% with respect to 100wt% of said main component. According to the present invention, a dielectric ceramic composition can be provided which is available to be sintered at low temperature (for example, 950°C or lower) while comparatively decreasing contents of a glass component, which shows good properties (specific permittivity, loss Q value and insulation resistance), and which is available to perform cofiring different materials.