Temperature Sensor Film with Chromium Oxide Adhesion Layer

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Solution Overview

Problem

Existing temperature sensor films using nickel thin-films on resin bases exhibit reduced temperature coefficient of resistance (TCR) and poor adhesion, leading to decreased measurement accuracy and ease of peeling.

Innovation Solution

Incorporating a chromium oxide thin-film as an underlying layer between the resin film base and the metal thin-film, with optional additional silicon oxide layer, to enhance adhesion and improve TCR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If heat treatment is performed to increase TCR, then temperature measurement accuracy is improved, but adhesion of metal thin-film deteriorates

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoidadhesion of metal thin-film
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

A chromium oxide thin-film layer is introduced as an intermediary between the resin film base and the nickel thin-film. This intermediate layer serves as a buffer that allows heat treatment to increase the TCR of the nickel film while maintaining adhesion through the chromium oxide layer, which has stable bonding properties with both the resin base and the metal film.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If metal thin-film is formed directly on resin film base, then manufacturing process is simplified, but adhesion deteriorates

Engineering Contradiction:
Improvemanufacturing process simplicityVSAvoidadhesion of metal thin-film
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The chromium oxide thin-film acts as an intermediate adhesion layer between the resin film base and the nickel thin-film. This single intermediate layer simplifies the manufacturing process compared to multiple adhesion layers while providing reliable bonding through its ability to chemically bond with both the organic resin base and the metal film.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If nickel thin-film is used for temperature sensing, then temperature coefficient of resistance is improved compared to copper, but adhesion to resin base deteriorates

Engineering Contradiction:
Improvetemperature coefficient of resistanceVSAvoidadhesion to resin base
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The chromium oxide thin-film serves as a mediator that enables the use of nickel thin-film for temperature sensing by providing the necessary adhesion to the resin base. The chromium oxide layer bonds well with both the nickel film (which has high TCR) and the resin base, allowing the high temperature sensitivity of nickel to be utilized without adhesion problems.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution results in a temperature sensor film with improved adhesion, processability, durability, and reliability, along with enhanced TCR, allowing for more accurate temperature measurements.

Implementation Method 1

an underlying layer including a chromium oxide thin-film formed on one principal surface of a resin film base, and a metal thin-film formed on the underlying layer. By disposing the chromium oxide thin-film on the resin film base as the underlying layer and disposing the metal thin-film on the chromium oxide thin-film directly or with another inorganic thin-film interposed therebetween, adhesion of the metal thin-film tends to be improved.

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

as a result of forming a nickel thin-film on a resin film base by a sputtering method

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentEP4040127B1Electroconductive film and temperature sensor film
Publication Date: 2025.10.22 NITTO DENKO CORP
  • EP4040127B1 patent drawingFigure 1~2
  • EP4040127B1 patent drawingFigure 3~4B
  • EP4040127B1 patent drawing

AI summary

Provided is an electroconductive film having a metal thin-film on a resin film base; and a temperature sensor film which is obtained by patterning the metal thin-film on the resin film base. An electroconductive film (101) which is used for the production of a temperature sensor film comprises a metal thin-film (10) on one principal surface of a resin film base (50), with a chromium oxide thin-film (21) serving as an underlying layer interposed therebetween. A temperature sensor film is obtained by patterning the metal thin-film so as to form a thermometric resistor part and a lead part that is connected to the thermometric resistor part.