Dielectric Ceramic Production via Wet-Pulverized Cordierite
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Solution Overview
Problem
Existing methods for producing dielectric ceramics face challenges in achieving low-temperature firing, reducing porosity, and simplifying the production process while maintaining desired dielectric characteristics, particularly when using low-melting-point metals like Cu or Ag, and are prone to particle aggregation and increased costs due to complex material handling and high firing temperatures.
Innovation Solution
A method involving the wet-pulverization of cordierite and low-temperature-sintering materials to create mixed powdery particles with a median diameter less than 1 μm, which are then fired at temperatures below 900°C, allowing for the use of low-melting-point metals and reducing porosity, while avoiding the need for pre-drying the low-temperature-sintering material to prevent particle aggregation and simplify the production steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high firing temperature (1300-1600°C) is used for alumina ceramic, then high melting point metals like W or Mo can be used for electrodes, but electric resistivity and loss in high-frequency range increase
Solution Approach 1:
The patent changes the firing temperature parameter from conventional high temperature (1300-1600°C for alumina) to low temperature (900-1000°C) by using a specific composition containing alumina (12-59.6% by mass), borosilicate based glass (18-69.6% by mass), and anorthite crystal (1-40% by mass). This parameter change enables the use of low melting point metals like Cu, Ag, or Au for electrodes, which have lower electric resistivity and loss in high-frequency range.
2Loss of energy
If low firing temperature (800-1000°C) is used to enable low melting point metals like Cu, Ag, or Au, then electric resistivity decreases, but the dielectric ceramic must be sintered at lower temperature which is difficult to achieve with conventional alumina
Solution Approach 1:
The patent creates a composite dielectric ceramic system combining alumina, borosilicate based glass, and anorthite crystal. The borosilicate glass acts as a flux that lowers the sintering temperature to 900-1000°C, enabling the use of low melting point metals like Cu, Ag, or Au while maintaining ceramic integrity. This composite approach allows sintering at temperatures suitable for low-resistance electrode materials.
3Strength
If alumina with high dielectric constant (about 10) is used, then ceramic substrate provides structural support, but transmission of high-frequency signals is delayed
Solution Approach 1:
The patent develops a composite dielectric ceramic with alumina (12-59.6% by mass), borosilicate based glass (18-69.6% by mass), and anorthite crystal (1-40% by mass) that achieves a dielectric constant of 6.5 or less while maintaining structural strength. The specific composition and sintering process create a dense microstructure that provides mechanical support with reduced dielectric constant, thereby decreasing signal transmission delay in high-frequency applications.
4Temperature
If borosilicate based glass is used in dielectric ceramic composition, then low temperature sintering is enabled, but B compound damages firing-furnace material and segregates during drying
Solution Approach 1:
The patent optimizes the composition parameters by controlling the ratio of alumina (12-59.6% by mass), borosilicate based glass (18-69.6% by mass), and anorthite crystal (1-40% by mass). This specific parameter range enables low temperature sintering (900-1000°C) while minimizing the harmful effects of boron compounds. The controlled composition reduces furnace material damage and prevents segregation during the drying process.
5Ease of manufacture
If conventional pulverization and drying process is used for low-temperature-sintering material, then material can be processed, but particle aggregation occurs and production steps increase
Solution Approach 1:
The patent merges the pulverization and drying steps into a single integrated process. The low-temperature-sintering material is pulverized together with cordierite or other inorganic filler materials without a separate drying step, reducing the number of production steps while preventing particle aggregation. This combined processing approach simplifies the manufacturing process while maintaining material quality.
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 enables the production of dielectric ceramics with a dielectric constant of 6.5 or less and an fQ product of 9 THz or more at 15 GHz, achieving denser microstructures and reducing production costs and time, while allowing for the use of low-melting-point metals like Cu or Ag, and minimizing substrate warpage and variation in shrinkage factors.
Implementation Method 1
calcining raw material powder including oxides of Al, Si, Sr, Bi, Na, K, Cu and Mn to cause these oxides to react with each other to vitrify the oxides partially
Implementation Method 2
firing the shaped body; wherein the method comprises the step of wet-pulverizing the low-temperature-sintering material together with at least the cordierite material
Data Source
AI summary
A method for producing a dielectric ceramic includes: shaping mixed powdery particles including a cordierite material (2MgO.2Al2O3.5SiO2) and a low-temperature-sintering material including Al, Si and Sr, the Si being partially vitrified; and firing the resultant shaped body. The method includes the step of wet-pulverizing the low-temperature-sintering material together with at least the cordierite material to prepare mixed powder particles having a median diameter D50 less than 1 μm; and, in a process until a time of the preparation of the mixed powder particles, the low-temperature-sintering material undergoes no step of wet-pulverizing only the low-temperature-sintering material, and drying the resultant pulverized material.