Ceramic Substrate Composition for Nonreciprocal Circuits
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Solution Overview
Problem
Existing ceramic material compositions for nonreciprocal circuit devices, such as isolators and circulators, face challenges in achieving a high dielectric constant while maintaining sinterability and resistance characteristics, particularly due to the degradation of resistance characteristics caused by the reaction between glass components and resistive materials.
Innovation Solution
A ceramic material composition comprising a BaO—TiO2—ReO3/2 ceramic composition combined with alumina and a borosilicate glass composition, optimized in terms of weight percentages, which allows for a high dielectric constant and avoids the use of alkali metals to prevent resistance degradation, enabling sintering at low temperatures and co-firing with metals like Ag or Cu.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Li2O is incorporated in the glass composition to reduce viscosity and improve sinterability, then sinterability is improved, but resistance characteristics of the resistor decreases due to reaction between glass component and resistive component
Solution Approach 1:
The patent removes Li2O (alkali metal oxide) from the glass composition to eliminate the harmful reaction with resistive components. The glass composition consists of SiO2, B2O3, Al2O3, and MO without any alkali metal oxides, thereby preventing degradation of resistance characteristics while maintaining sinterability through optimized composition ratios.
Solution Approach 2:
The patent changes the chemical composition parameters of the glass by specifying precise weight percentage ranges of SiO2 (40-70%), B2O3 (10-30%), Al2O3 (5-20%), and MO (10-30%), eliminating alkali metal oxides. This parameter optimization achieves both improved sinterability and preserved resistance characteristics.
2Quantity of substance
If the content of BaO—TiO2—ReO3/2 ceramic composition is increased to achieve high dielectric constant, then dielectric constant is improved, but sinterability is degraded
Solution Approach 1:
The patent creates a composite material system combining BaO-TiO2-ReO3/2 ceramic composition (40-70 wt%) with alumina (5-20 wt%) and a specially formulated glass composition (10-30 wt%). This composite approach maintains high dielectric constant while the glass phase acts as a sintering aid to preserve sinterability.
Solution Approach 2:
The patent optimizes the composition parameters by controlling the weight percentages of each component: BaO-TiO2-ReO3/2 (40-70%), alumina (5-20%), and glass composition (10-30%). The glass composition itself has optimized parameters with SiO2 (40-70%), B2O3 (10-30%), Al2O3 (5-20%), and MO (10-30%), which enables sintering at lower temperatures despite high ceramic content.
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 results in a ceramic substrate with a high dielectric constant, reduced size, and preserved resistance characteristics, allowing for the production of nonreciprocal circuit devices with improved performance and reliability.
Implementation Method 1
the dielectric constant of the ceramic material constituting the ceramic substrate must be increased
Implementation Method 2
can be sintered at as low as 1,000° C. or lower
Data Source
AI summary
A ceramic material composition advantageously used as a material for a ceramic substrate containing for example a resistor such as an isolator disposed therein.includes about 10 to 45 percent by weight of a BaO—TiO2—ReO3/2 ceramic composition, the ceramic composition being represented by xBaO-yTiO2-zReO3/2 (wherein x, y, and z each represent mole percent, 8≦x≦18, 52.5≦y≦65, and 20≦z≦40, and x+y+z=100; and Re represents a rare-earth element); about 5 to 40 percent by weight of alumina; and about 40 to 65 percent by weight of a borosilicate glass composition containing about 4 to 17.5 percent by weight of B2O3, about 28 to 50 percent by weight of SiO2, 0 to about 20 percent by weight of Al2O3, and about 36 to 50 percent by weight of MO (wherein MO represents at least one compound selected from CaO, MgO, SrO and BaO), wherein the total content of the BaO—TiO2—ReO3/2 ceramic composition and alumina is about 35 percent by weight or more.