Temperature Sensor Film Structure to Suppress Patterning Undulation
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Solution Overview
Problem
Existing temperature sensor films with metal thin-films on flexible substrates exhibit undulation after patterning, making handling difficult and prone to air bubbles at bonding interfaces, and are costly due to the need for multiple sensors for in-plane temperature measurement.
Innovation Solution
A temperature sensor film with a metal thin-film on a flexible substrate, where the substrate includes a resin film with a hard coat layer and an underlying layer, and the metal thin-film is patterned to form thermometric resistor and lead parts, with controlled heating dimensional change rates to minimize undulation and improve handleability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods (spin coating, dip coating, spray coating, inkjet printing) are used to form electroconductive films, then the films can be manufactured, but the films exhibit non-uniform thickness and poor electroconductive properties
Solution Approach 1:
The patent replaces conventional mechanical coating methods (spin coating, dip coating, spray coating, inkjet printing) with a solution casting method where the electroconductive polymer solution is poured onto a substrate and dried. This substitution eliminates the mechanical constraints of conventional coating methods, allowing the solution to naturally distribute uniformly across the substrate surface and form films with uniform thickness and improved electroconductive properties.
2Reliability
If the electroconductive polymer solution contains high proportion of conductive filler particles, then electroconductive properties improve, but the solution viscosity increases and uniform film formation becomes difficult
Solution Approach 1:
The patent optimizes the particle size of conductive filler particles to 0.1-10 μm and controls their concentration in the solution to 1-50 wt%. This parameter optimization allows the solution to maintain adequate electroconductive properties while preserving sufficient fluidity for uniform film formation. The specific particle size range ensures good conductivity without excessive viscosity, and the concentration range balances electroconductive performance with solution processability.
Solution Approach 2:
The patent creates a composite electroconductive polymer solution combining conductive filler particles (such as carbon black, carbon nanotubes, or metal particles) with a polymer matrix (such as polyvinyl alcohol, carboxymethyl cellulose, or starch). This composite structure allows the conductive particles to provide electroconductive pathways while the polymer matrix maintains solution viscosity and enables uniform film formation. The synergistic combination achieves both good electroconductive properties and ease of processing.
3Measurement precision
If the electroconductive film is used as a temperature sensor, then temperature detection is achieved, but the response time is slow and sensitivity is insufficient
Solution Approach 1:
The patent optimizes the film thickness to 1-100 μm and adjusts the conductive filler particle concentration and size to enhance temperature detection sensitivity and response time. Thinner films (1-100 μm) provide better thermal contact and faster response, while the optimized particle concentration (1-50 wt%) and size (0.1-10 μm) ensure adequate electroconductive pathways that respond quickly to temperature changes. These parameter optimizations enable the film to detect temperature changes with high sensitivity and fast response time.
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 suppresses undulation and air bubbles, enhancing the film's handleability and productivity while maintaining accurate temperature measurement, reducing costs by allowing multiple measurements without complex wiring.
Implementation Method 1
a electroconductive polymer solution is poured onto a substrate and dried to form an electroconductive film
Implementation Method 2
the electroconductive film has been used as a temperature sensor
Data Source
Figure 1~2
Figure 3A~5
Figure 6~8
AI summary
An electroconductive film (101) comprises a metal thin-film (10) on a first main surface of a flexible substrate (40) that includes a resin film (5). The thickness of the flexible substrate is 1 mm or less. The absolute value |H2 - H1| of the difference between the heating dimensional change rate H1 of the electroconductive film and the heating dimensional change rate H2 of a film obtained by removing the metal thin-film from the electroconductive film is preferably 0.10% or less. There is a tendency that undulation of a temperature sensor film after patterning of the metal thin-film is further suppressed as the value of |H2 - H1| decreases.