Wiring Layer Phonon Mean Free Path Reduction for Thermistor Heat Utilization

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Solution Overview

Problem

In heat utilizing devices, such as infrared sensors, the thermal resistance of the wiring layer is not effectively increased without increasing the electric resistance, leading to inefficient heat dissipation and potential measurement errors due to heat conduction from the wiring layer.

Innovation Solution

The wiring layer is designed with a reduced mean free path of phonons by forming a meandering pattern and using insulating materials to limit heat conduction while maintaining electric conductivity, thereby reducing heat dissipation without significantly increasing electric resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the wiring layer is made of conductive material to supply current to the thermistor, then electric conductivity is improved, but thermal resistance decreases leading to excessive heat conduction

Engineering Contradiction:

Improveelectric conductivityVSAvoidheat conduction

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent changes the physical parameters of the wiring layer by reducing the mean free path of phonons through specific material selection or structural design. This allows the wiring layer to maintain low electric resistance while achieving high thermal resistance, effectively decoupling the typically correlated electrical and thermal conductivity parameters.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures in the wiring layer, combining materials with different phonon mean free path characteristics. This composite approach enables the wiring layer to exhibit selective transport properties - high electrical conductivity while maintaining high thermal resistance through controlled phonon scattering.

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If the wiring layer is made of insulating material to increase thermal resistance, then heat conduction is limited, but electric resistance increases leading to higher power consumption

Engineering Contradiction:

Improveheat conductionVSAvoidelectric resistance

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

The patent fundamentally changes the thermal transport parameter (phonon mean free path) in the wiring layer, enabling it to achieve high thermal resistance while maintaining low electrical resistance. This parameter change allows the wiring layer to simultaneously satisfy both requirements that are typically mutually exclusive in conventional materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the typically harmful effect of heat conduction in the wiring layer into a beneficial feature by controlling phonon transport. The wiring layer's heat conduction is deliberately limited through reduced phonon mean free path, transforming what would normally be a source of measurement error into an advantage that improves sensor accuracy while maintaining electrical functionality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Use of energy by moving object

If heat conduction in the wiring layer is increased to reduce power consumption, then electric resistance decreases, but measurement error increases due to heat dissipation from the thermistor

Engineering Contradiction:

Improvepower consumptionVSAvoidmeasurement error

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes to the thermal transport properties of the wiring layer by reducing the phonon mean free path. This creates a selective transport regime where electrical current flows efficiently while heat conduction is suppressed, thereby reducing the measurement error caused by heat dissipation from the thermistor through the wiring layer.

Inventive Principle:

Principle #35Parameter changes

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

This configuration enhances the thermal resistance of the wiring layer while minimizing the increase in electric resistance, improving the sensitivity and accuracy of temperature measurements by limiting heat dissipation and maintaining efficient power consumption.

Implementation Method 1

a thermistor whose electric resistance changes depending on temperature

Methodology Applied

Scientific EffectThermal resistance change: Thermistor

Implementation Method 2

A mean free path of phonons in the wiring layer is smaller than a mean free path of phonons in an infinite medium that consists of a material of the wiring layer

Methodology Applied

Scientific EffectPhonon transport: Conduction (thermal)

Data Source

PatentUS11480477B2Heat utilizing device

Publication Date: 2022.10.25 TDK CORP

AI summary

A heat utilizing device is provided in which the thermal resistance of the wiring layer is increased while an increase in electric resistance of the wiring layer is limited. Heat utilizing device has thermistor whose electric resistance changes depending on temperature; and wiring layer that is connected to thermistor. A mean free path of phonons in wiring layer is smaller than a mean free path of phonons in an infinite medium that consists of a material of wiring layer.