Lead-Free Dielectric Material for Ultrasonic Sensor Temperature Compensation
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Solution Overview
Problem
Current dielectric materials for temperature compensation in piezoelectric ultrasonic wave sensors, particularly those used in vehicle applications, face challenges with high temperature coefficient of capacitance (TCC) and relative permittivity, often requiring lead-based materials that are toxic and difficult to handle, limiting their effectiveness and safety in wide temperature ranges.
Innovation Solution
A lead-free dielectric material represented by the chemical formula (Ba1-a-b-3c/2SraMgbLac)(Ti1-xSnx)O3, where a, b, c, and x are within specific ranges, is developed, offering a high temperature compensation rate and relative permittivity without using lead, achieved through a mixture of barium carbonate, titanium dioxide, tin dioxide, lanthanum oxide, and magnesium oxide, sintered at specific temperatures to optimize temperature compensation in ultrasonic wave sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-based dielectric materials are used to achieve high relative permittivity and temperature compensation, then the temperature compensation performance is improved, but the environmental safety and ease of handling deteriorate due to toxicity
Solution Approach 1:
The patent removes lead (Pb) from the dielectric material composition entirely, extracting the harmful element while maintaining the functional requirements through alternative material combinations of barium, strontium, magnesium, lanthanum, titanium, and tin oxides
Solution Approach 2:
The patent employs a composite oxide material system with multiple cations (Ba, Sr, Mg, La, Ti, Sn) in specific ratios to achieve the desired dielectric properties without lead, combining multiple materials to compensate for the removal of lead-based components
2Quantity of substance
If the thickness of the temperature compensation device is decreased to increase electrostatic capacity, then the electrostatic capacity is improved, but the strength and ease of handling deteriorate
Solution Approach 1:
The patent changes the material parameters (relative permittivity and TCC) of the dielectric material to achieve the desired electrostatic capacity without reducing thickness, using a relative permittivity of 1000-3000 and TCC of -5000 to -30000 ppm/°C to maintain both capacity and structural integrity
3Ease of manufacture
If conventional dielectric materials with lower relative permittivity are used, then the ease of manufacture is improved, but the device size and effectiveness deteriorate
Solution Approach 1:
The patent achieves high relative permittivity (1000-3000) through specific compositional parameters and sintering conditions, enabling downsizing of the temperature compensation device while maintaining manufacturability through established ceramic processing techniques
4Productivity
If the temperature compensation device is downsized to improve integration, then the productivity is improved, but the handling and manufacturing difficulty increase
Solution Approach 1:
The patent optimizes the material parameters to achieve the right balance between size and strength, using specific compositional ratios and sintering temperatures to produce a compact yet mechanically robust temperature compensation device that is easy to handle and integrate
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 dielectric material provides a negative TCC of -5,000 to -30,000 ppm/°C and relative permittivity of 1,000 to 3,000, effectively compensating for temperature changes in a wide range of -40 to 80°C, enabling downsizing of the temperature compensation device and ensuring environmental safety by avoiding toxic lead.
Implementation Method 1
A temperature coefficient of capacitance (TCC) indicates a temperature compensation rate of an electrostatic capacity temperature compensation material to a reference temperature of 25° C.
Implementation Method 2
relative permittivity of about 2,000 or more
Implementation Method 3
sintering the mixture at a temperature ranging from about 1280 to about 1360° C. for about 1 to about 3 hours
Data Source
AI summary
The present invention provides a dielectric material for temperature compensation of Chemical Formula 1 and a method of preparing the same. (Ba1-a-b-3c/2SraMgbLac)(Ti1-xSnx)O3 Chemical Formula 1 In the above Chemical Formula 1, a is 0≦̸a<0.20; b is 0<b <0.05; c is 0<c<0.01; and x is 0<x<0.20 as defined in the detailed description.