Heat-Sensitive Paste Resistors with Polymer Additives for Thermal Sensitivity
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Solution Overview
Problem
Existing temperature detection sensors made of resistive pastes lack sufficient sensitivity and resistance value, particularly in Wheatstone bridge assemblies, which limits their accuracy and effectiveness in thermal imaging and temperature measurement.
Innovation Solution
Incorporating a polymer with a dielectric constant between 2 and 3, a molar mass between 50,000 and 150,000 g/mol, and a glass transition temperature between 40 and 100°C into NTC and PTC resistive elements, specifically antimony tin oxide or carbon black, to enhance the resistive properties and sensitivity, and forming resistive tracks in series to create adjustable temperature thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional resistive pastes are used without polymer additives, then the device structure remains simple, but the temperature sensitivity and resistance value are insufficient
Solution Approach 1:
The patent applies composite materials by combining traditional resistive paste components (antimony tin oxide or carbon black) with specifically selected polymer additives having controlled molecular weight and glass transition temperature. This composite approach enhances temperature sensitivity and resistance values while maintaining the fundamental paste structure, directly resolving the contradiction between improved measurement precision and increased device complexity.
Solution Approach 2:
The patent utilizes parameter changes by carefully selecting polymers with specific dielectric constants (2-3), molecular weights (50,000-150,000 g/mol), and glass transition temperatures (40-100°C). By adjusting these material parameters, the invention optimizes temperature sensitivity and resistance characteristics without fundamentally altering the device architecture, thereby improving measurement precision while controlling complexity.
2Measurement precision
If NTC and PTC resistors are assembled in a Wheatstone bridge to increase measurement accuracy, then the measurement precision improves, but the resistance value of individual resistive elements needs to be increased
Solution Approach 1:
The patent employs composite materials in the resistive paste formulation to achieve higher resistance values that are suitable for Wheatstone bridge configurations. The polymer additives modify the electrical properties of the resistive paste, enabling individual resistors to have appropriate resistance values for bridge assemblies, thus supporting improved measurement precision through the Wheatstone bridge topology.
Solution Approach 2:
The invention applies parameter changes by selecting polymers with specific glass transition temperatures (40-100°C) and dielectric constants to tune the resistance characteristics of NTC and PTC elements. This enables the resistors to achieve optimal resistance values for Wheatstone bridge operation, resolving the need for increased resistance quantity while maintaining measurement accuracy improvements.
3Measurement precision
If polymer additives are added to increase resistivity and temperature sensitivity, then the measurement precision and sensitivity improve, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by defining specific ranges for polymer properties (molecular weight 50,000-150,000 g/mol, glass transition temperature 40-100°C, dielectric constant 2-3) that optimize sensitivity while considering manufacturability. These parameter specifications enable consistent performance without requiring overly complex manufacturing processes, as the polymer additives can be incorporated into standard paste formulations.
Solution Approach 2:
The invention applies local quality by selectively adding polymer additives only to the resistive paste material where they are needed to enhance temperature sensitivity, rather than modifying the entire sensor structure. This localized approach improves sensitivity while minimizing the impact on manufacturing complexity, as only the paste composition requires modification.
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 introduction of the polymer significantly increases the resistivity and temperature sensitivity of the resistive pastes, allowing for higher sensitivity and adjustable resistance characteristics, particularly in Wheatstone bridge configurations, achieving sensitivities of up to 100 mV/°C at 60°C, compared to 30 mV/°C without the polymer.
Implementation Method 1
containing a polymer having a dielectric constant between 2 and 3
Implementation Method 2
a glass transition temperature Tg between 40 and 100° C.
Implementation Method 3
Resistive pastes with a negative temperature coefficient, currently called NTC
Implementation Method 4
Heat-sensitive resistive pastes with a positive temperature coefficient, currently called PTC
Implementation Method 5
In a PTC resistor, the value of the electric resistance increases as the temperature increases. In a NTC resistor, the value of the electric resistance decreases as the temperature increases.
Data Source
AI summary
A heat-sensitive resistor with a negative or positive temperature coefficient comprises respectively an antimony-doped tin oxide-based resistive element or a carbon black-based resistive element, containing a polymer having a dielectric constant between 2 and 3, a molar mass between 50000 and 150000 g/mol, and a glass transition temperature Tg between 40 and 100° C.