Polymer Coating Thickness Measurement Using Contactless Ellipsometry

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Solution Overview

Problem

Measuring the thickness of polymer coatings on flexible metal substrates, such as lithium metal anodes in rechargeable batteries, is challenging due to the risk of physical damage and inaccuracy with existing methods, particularly when the coating is not in a crystalline phase.

Innovation Solution

A contactless optical measurement system using ellipsometry to determine the thickness of the polymer coating by transmitting a polarized light signal through the coating, measuring the polarization difference of the reflected signal, and calculating the thickness based on correlated data points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If contactless optical measurement system is used, then measurement accuracy and non-destructiveness are improved, but device complexity increases

Engineering Contradiction:

Improvecoating thickness measurement accuracyVSAvoidoptical measurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical contact measurement methods with an optical measurement system that uses polarized light to measure coating thickness. The system transmits light through the coating, detects polarization changes in the reflected light, and calculates thickness without physical contact, thereby improving measurement accuracy while avoiding damage to the flexible substrate and coating.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces polarized light as an intermediary medium to transfer measurement information from the coating to the detector. By using the polarization state of light as the mediator, the system can extract thickness information without direct mechanical contact, resolving the contradiction between non-destructive measurement and device complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If existing measurement methods are used, then device complexity is reduced, but physical damage and contamination risk increase

Engineering Contradiction:

Improvemeasurement system simplicityVSAvoidphysical damage and contamination

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical measurement tools that physically contact the coating with an optical system. The light-based measurement method eliminates mechanical stress, scratching, and contamination risks associated with contact methods, while the system complexity increase is justified by the elimination of harmful effects.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If polymer coating thickness is not uniformly controlled, then manufacturing complexity is reduced, but battery performance deteriorates

Engineering Contradiction:

Improvecoating thickness controlVSAvoidion distribution uniformity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent uses optical measurement to precisely characterize coating thickness variations, enabling better control of the coating process. By accurately measuring thickness at different locations, manufacturers can optimize coating parameters to achieve uniform thickness, ensuring reliable ion distribution and battery performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables accurate and non-destructive measurement of the coating thickness, avoiding contamination and physical damage, and improving the uniformity of ion distribution on the anode, thus enhancing battery performance.

Implementation Method 1

Methodology Applied

Scientific EffectEllipsometry: Polarisation

Implementation Method 2

transmitting a light signal having a known first polarization toward the anode substrate through the coating such that the light signal is reflected from the surface of the anode substrate

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS11852457B2Contactless method for polymer coating thickness measurement

Publication Date: 2023.12.26 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A system for measuring a thickness of a coating arranged on an anode substrate includes an optical measurement system configured to transmit a light signal having a known first polarization toward the anode substrate through the coating such that the light signal is reflected from the surface of the anode substrate, a detection module positioned to receive the reflected light signal and configured to determine a second polarization of the reflected light signal that is different from the first polarization and measure a polarization difference between the first polarization and the second polarization, and a measurement module configured to receive the measured polarization difference, calculate the thickness of the coating based on the measured polarization difference, and generate an output based on the calculated thickness.