Polysilicon Thermistor Die on Ceramic Substrate for Long-Distance Sensing
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Solution Overview
Problem
Conventional thermistor probes embedded with metal oxide particles in ceramic, epoxy, or glass are costly and lack mechanical robustness, limiting their application in temperature sensing, especially in scenarios requiring long-distance connections.
Innovation Solution
The development of die-based thermistor probes, where a thermistor die is mounted on a substrate with interconnects and wires extending beyond, encapsulated with a material for mechanical robustness and miniaturization, allowing for long-distance temperature sensing without modifying the device under test.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermistor probes with metal oxide particles embedded in ceramic, epoxy, or glass are used, then temperature sensing capability is provided, but cost is high and mechanical robustness is poor
Solution Approach 1:
The patent changes the material parameters by replacing conventional metal oxide particles in ceramic/epoxy/glass with a polysilicon-based thermistor material. This parameter change achieves both lower cost and improved mechanical robustness while maintaining temperature sensing functionality.
Solution Approach 2:
The patent employs composite material structure by integrating the polysilicon thermistor die with a ceramic substrate and encapsulating it with epoxy molding compound. This composite approach provides mechanical robustness through the ceramic and epoxy while keeping costs lower than conventional fully-ceramic constructions.
2Ease of operation
If conventional thermistor probes are used, then temperature sensing is achieved, but the structure is fragile and不适合 long-distance connections
Solution Approach 1:
The patent performs preliminary encapsulation of the fragile polysilicon thermistor die within epoxy molding compound and attaches it to a ceramic substrate before wire bonding. This preliminary protective action strengthens the structure to enable long-distance connections while preserving the sensing capability.
Solution Approach 2:
The patent introduces a ceramic substrate as an intermediary between the fragile polysilicon thermistor die and the external wiring. This intermediary provides mechanical strength and structural support, enabling the device to withstand long-distance connection requirements.
3Ease of manufacture
If polysilicon-based thermistor die is used, then cost is reduced and mechanical robustness is improved, but additional fabrication steps are required
Solution Approach 1:
The patent segments the manufacturing process into distinct stages: fabricating the polysilicon thermistor die separately, mounting it on a ceramic substrate, and then encapsulating with epoxy. This segmentation allows each component to be optimized independently, reducing overall cost despite increased process steps.
Solution Approach 2:
The patent makes the ceramic substrate multi-functional by using it both as a mechanical support structure and as a mounting platform for the thermistor die. This universality reduces the need for additional components, offsetting the increased fabrication complexity.
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
Die-based thermistor probes offer improved mechanical and electrical performance, enabling accurate temperature sensing over long distances with enhanced precision, accuracy, and robustness, suitable for applications in automobiles, machines, and heavy equipment.
Implementation Method 1
a temperature variable resistor... measure the resistance before calculating the temperature... R2 is a resistance of the thermistor that varies with temperature
Implementation Method 2
An encapsulating material is formed over the thermistor die and a die end of the first and second wires
Data Source
AI summary
A thermistor-based thermal probe includes a thermistor die having a thermistor thereon with first and second bond pads coupled across the thermistor, and first and second die interconnects coupled to the respective bond pads. First and second wires W1, W2 that extend beyond the thermistor die are attached to the first and to the second die interconnects, respectively. An encapsulant material encapsulates the thermistor die and a die end of the first and second wires.