Flexible Thermistor Thin Film on Metal Base for Thermal Stress
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Solution Overview
Problem
Conventional thermistor devices experience stress fractures and cracking due to thermal expansion mismatch between the heat-resistant resin sheets and the thermistor element, leading to unreliable temperature sensing.
Innovation Solution
A thermistor device with a flexible thermistor thin film integrated on a metal base material, connected by lead electrodes on a thin resin base material sheet, which undergoes deflection to absorb thermal stress, enhancing stress tolerance and maintaining connection integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat-resistant resin sheets are used to support lead electrodes and thermistor element, then structural support and electrical insulation are provided, but thermal expansion mismatch causes stress fractures and cracking
Solution Approach 1:
The patent introduces a flexible support structure that can accommodate thermal expansion differences between the resin sheets and thermistor element. The flexibility allows the structure to deform elastically under thermal stress rather than fracturing, maintaining connection integrity while providing structural support.
Solution Approach 2:
The patent modifies the mechanical parameters of the support structure by introducing flexibility and elastic deformation capabilities. This allows the structure to dynamically adjust its rigidity based on thermal conditions, remaining rigid enough for support but flexible enough to absorb expansion stress.
2Stability of the object's composition
If resin sheets are closely attached with heat-resistant adhesive, then structural stability is improved, but stress from differential expansion fractures connection parts
Solution Approach 1:
The patent incorporates stress-absorbing elements or flexible interfaces in advance within the attached structure. These elements act as cushions that absorb the differential expansion stress before it can propagate to fracture the connection parts, allowing stable attachment while protecting against thermal stress.
Solution Approach 2:
The patent introduces an intermediary layer or flexible interface between the resin sheets and connection parts. This intermediary absorbs and distributes the thermal expansion stress, preventing direct stress transmission that would cause fractures while maintaining the structural stability provided by the adhesive attachment.
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 flexible thermistor device effectively absorbs thermal expansion stress, ensuring reliable temperature detection and preventing fractures, while maintaining high accuracy and speed in temperature measurement.
Implementation Method 1
the heat-resistant resin sheet and exterior sheet made of polyimide expand with the changes in the temperature of the object to be detected. In general, the resin (heat-resistant resin sheet and exterior sheet) expands more than the thermistor element
Implementation Method 2
each of the thermistor thin film and the metal base material undergoes a deflection between the first external electrode and the second external electrode
Data Source
AI summary
In order to further improve stress tolerance, a thermistor device includes a first base material member made of resin, a thermistor element including a thermistor thin film provided on a metal base material and first and second external electrodes provided on the thermistor thin film, and a first lead electrode and a second lead electrode provided on a principal surface of the first base material member, and connected to the first external electrode and the second external electrode. Each of the metal base material and the thermistor thin film undergoes a deflection between the first external electrode and the second external electrode.