Dielectric Ceramic Composition for Low Thermal Expansion
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Solution Overview
Problem
Conventional dielectric ceramic compositions with high thermal expansion coefficients cause delamination and cracks when fired simultaneously with materials having lower thermal expansion coefficients, making them unsuitable for miniaturized electronic components requiring low thermal expansion and high dielectric constants.
Innovation Solution
A dielectric ceramic composition comprising ATiO3 and AAl2Si2O8 phases with specific compositional ranges of Al, Si, A, and additional elements, achieving a high dielectric constant of 10 or higher and a thermal expansion coefficient of less than 7 ppm/°C, allowing for simultaneous firing with conductors like silver, copper, or gold at temperatures below 1000°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a dielectric ceramic composition with high thermal expansion coefficient (7.0 ppm/°C or higher) is used to achieve high dielectric constant, then the dielectric constant is improved, but delamination and cracks occur when fired simultaneously with materials having lower thermal expansion coefficients
Solution Approach 1:
The patent modifies the thermal expansion coefficient parameter of the dielectric ceramic composition by controlling the content of low-melting-point glass phases and crystalline phases. Specifically, it adjusts the composition to contain 1-10 wt% low-melting-point glass and 90-99 wt% crystalline phase (such as Al2O3, MgAl2O4, and perovskite phases), achieving a thermal expansion coefficient of 5.0-7.0 ppm/°C while maintaining high dielectric constant of 10 or more at 3 GHz
Solution Approach 2:
The patent creates a composite dielectric ceramic composition consisting of multiple phases including low-melting-point glass phase, crystalline phases (Al2O3, MgAl2O4, perovskite), and optional secondary phases. This composite structure allows the material to simultaneously achieve high dielectric constant through the perovskite phase while controlling thermal expansion through the balanced composition of glass and crystalline phases, preventing delamination when fired with materials having lower thermal expansion coefficients
2Length of moving object
If conventional dielectric ceramic composition is used, then the material has sufficient thermal expansion coefficient, but the dielectric constant is insufficient for miniaturization requirements
Solution Approach 1:
The patent increases the dielectric constant parameter by optimizing the composition to contain 1-10 wt% low-melting-point glass and 90-99 wt% crystalline phase with high dielectric constant components. The perovskite phase (CaTiO3, SrTiO3, or BaTiO3) specifically contributes to achieving dielectric constant of 10 or more at 3 GHz, enabling component miniaturization while maintaining the required thermal expansion coefficient of 5.0-7.0 ppm/°C
3Reliability
If high temperature firing is used to achieve proper sintering, then the dielectric material properties are improved, but conductors with low melting points cannot be fired simultaneously
Solution Approach 1:
The patent lowers the firing temperature parameter by incorporating 1-10 wt% low-melting-point glass phase that becomes active at lower temperatures. This glass phase facilitates sintering and bonding at temperatures suitable for low-melting-point conductors (silver, copper, gold) while still achieving adequate dielectric material properties through the controlled composition of crystalline phases and glass 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 composition enables the production of multilayer dielectric substrates with improved thermal stability and dielectric properties, preventing delamination and cracks, while allowing for the miniaturization of electronic components by maintaining a low thermal expansion coefficient and high dielectric constant.
Implementation Method 1
the dielectric material needs to be one to be sintered at a temperature of 1,000° C. or lower, and preferably 900° C. or lower
Implementation Method 2
it has as low a thermal expansion coefficient as about 5 ppm/° C.
Data Source
AI summary
Disclosed is a dielectric ceramic composition which has high dielectric constant and suppressed low thermal expansion coefficient. Also disclosed are a multilayer dielectric substrate using the dielectric ceramic composition, and an electronic component. Specifically disclosed is a dielectric ceramic composition which contains an ATiO3 (wherein A represents either Ca and/or Sr) phase and an AAl2Si2O8 phase, said dielectric ceramic composition being characterized in that the dielectric constant is not less than 10 at 3 GHz and the average thermal expansion coefficient over the temperature range of 40-600° C. is less than 7 ppm/° C.