ISO 20508:2003

Fine ceramics (advanced ceramics, advanced technical ceramics) - Determination of light transmittance of ceramic films with transparent substrate

ISO 20508:2003 specifies a test method for determining the visible light transmittance of a transparent coating material, e.g., the transparent electrode for display devices, in which a fine ceramic thin film is coated on to a substrate. ISO 20508:2003 is not applicable to deliberately coloured, uneven or non-parallel faced test pieces. A translucent medium is not included in this International Standard.

Céramiques techniques — Détermination de la transmission de la lumière des films céramiques avec substrats transparents

General Information

• Status: Published
• Publication Date: 27-Nov-2003
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: ISO/TC 206 - Fine ceramics
• Drafting Committee: ISO/TC 206/WG 10 - Coatings
• Current Stage: 9020 - International Standard under periodical review
• Start Date: 15-Oct-2025
• Completion Date: 15-Oct-2025

Relations

• Consolidated By: ISO 2553:2013 - Welding and allied processes - Symbolic representation on drawings - Welded joints
• Effective Date: 06-Jun-2022

Overview

ISO 20508:2003 is an international standard developed by ISO Technical Committee ISO/TC 206 that specifies a precise test method for determining the visible light transmittance of fine ceramic thin films coated on transparent substrates. These coatings, often used as transparent electrodes in display devices and advanced ceramic applications, require accurate measurement of light transmittance to ensure optimal optical performance.

This standard addresses the evaluation of transparent ceramic films, excluding deliberately colored, uneven, or non-parallel test pieces and does not cover translucent media. The document outlines testing conditions, apparatus requirements, calibration methods, and reporting protocols to guarantee reliable and reproducible transmittance measurement results.

Key Topics

• Scope and Applicability
  ISO 20508:2003 applies specifically to transparent fine ceramic thin films on substrates such as glass. The standard excludes non-parallel surfaces, colored films, or translucent materials to maintain measurement accuracy.

• Test Methodology
  The method involves measuring spectral transmittance-light transmitted through the film at specific wavelengths between 380 nm and 780 nm-using a spectrophotometer. An air blank serves as the 100% transmittance reference, rather than the substrate alone.

• Measurement Conditions

  • Test pieces are positioned perpendicular to the incident light beam with a tolerance of ±1°.
  • Spectral bandwidth of the light source beam should be less than 10 nm, preferably under 2 nm.
  • Test environment temperature is maintained between 15°C and 27°C, with humidity between 5% and 85%, free from disturbing vibrations.

• Apparatus and Calibration

  • Use of a spectrophotometer with high wavelength accuracy (±0.5 nm) and photometric accuracy (±0.5%).
  • Certified wavelength and transmittance standards (e.g., from NIST or JQA) are essential for calibration and performance verification to ensure reliable results.

• Reporting Requirements Detailed test reports must include reference to ISO 20508, testing establishment details, spectrophotometer specifications, certification of reference materials, test-piece descriptions, measurement conditions, and the digitized transmittance data.

Applications

ISO 20508:2003 serves critical roles across industries that employ fine ceramic thin films requiring optical transparency assessment. Typical practical applications include:

• Display Technology
  Assessment of transparent ceramic electrodes in liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs), and other flat panel displays to optimize light transmission and device efficiency.

• Optical Coatings
  Quality control and performance validation of advanced technical ceramics used in optical filters, sensors, and functional coatings where light transmittance is a key parameter.

• Research & Development
  Supports materials scientists and engineers working on new transparent ceramic films by providing standardized measurement procedures for comparative studies.

• Manufacturing Quality Assurance
  Enables manufacturers of advanced ceramics to routinely verify coating uniformity and optical clarity, ensuring conformance to customer and industry specifications.

Related Standards

ISO 20508:2003 is part of a larger framework of standards addressing fine ceramics and their properties. Related standards include:

• ISO/TC 206 series - Covers various test methods for properties of advanced ceramics such as mechanical strength, electrical resistance, and thermal stability.

• IEC Standards on Electrotechnical Materials - Often referenced alongside ISO standards for testing materials used in electronic and display components.

• National Metrology Institutes’ Standards - Calibration and reference materials standardized by organizations like NIST ensure traceability and harmonization of measurement results globally.

Conclusion

ISO 20508:2003 delivers a rigorously defined procedure for measuring visible light transmittance of fine ceramic films on transparent substrates, an essential quality parameter for advanced ceramics in optical and electronic applications. Its precise methodology, coupled with strict calibration and environment controls, ensures reliable, reproducible results that support innovation, manufacturing excellence, and product quality in the advanced ceramics sector.

Keywords: ISO 20508, fine ceramics, advanced ceramics, light transmittance measurement, ceramic films, transparent substrate, spectrophotometer, visible light transmittance, transparent electrode, display devices, test method, spectral transmittance, certified reference materials, optical coatings.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 20508
First edition
2003-12-01
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Determination of light transmittance of
ceramic films with transparent substrate
Céramiques techniques — Détermination de la transmission de la
lumière des films céramiques avec substrats transparents

Reference number
©
ISO 2003
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ii ISO 2003 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 20508 was prepared by Technical Committee ISO/TC 206, Fine ceramics.
©
ISO 2003 – All rights reserved iii

.
iv
INTERNATIONAL STANDARD ISO 20508:2003(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Determination of light transmittance of ceramic
films with transparent substrate
1Scope
This International Standard specifies a test method for determining the visible light transmittance of a
transparent coating material, e.g., the transparent electrode for display devices, in which a fine ceramic thin film
is coated on to a substrate. This International Standard is not applicable to deliberately coloured, uneven or
non-parallel faced test pieces. A translucent medium is not included in this International Standard.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
transmittance
proportion of incident light which is transmitted through a transparent or semi-transparent body for a given
luminous flux, expressed as a percentage
2.2
spectral transmittance
proportion of incident light which is transmitted through a transparent or semi-transparent body for a given
monochromatic wavelength, expressed as a percentage
2.3
reference
means of providing 100 % transmittance that, for the purposes of this International Standard, is considered to
be an air blank
3 Principle of test and measurement
This International Standard concerns the measurement of spectral transmittance using a spectrophotometer,
employing an air blank as a transmittance reference. The substrate alone shall not be used as the
100 %
reference. The schematic diagram of the measurement equipment is shown in Figure 1. The transmittance is
measured by placing the test piece perpendicular to the light beam as indicated in Figure 2 so that the beam is
incident perpendicularly on the film side of the test piece and transmitted to the substrate side and thence to the
detector.
4 Test environment and test conditions
4.1 Test environment
◦ ◦
The test shall be carried out at a temperature between 15C2 and 7C3 and in an environment of between 5%
and 85 % humidity and which is free from mechanical vibrations that may affect the measurement. If there are
specific conditions of use specified for the spectrophotometer, they shall be followed.
©
ISO 2003 – All rights reserve
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