ISO 21318:2007

Plastics - Epoxy resins - Determination of electrical conductivity of aqueous resin extracts

ISO 21318:2007 specifies a method for the determination of the electrical conductivity of an aqueous extract obtained by extraction of an epoxy resin with water at 95 °C. The method is applicable only to epoxy resins that are in the molten state at the extraction temperature (95 °C). The method is important for epoxy resins which are used as insulation materials for electronic devices. The electrical conductivity of the extract is used as a measure of the concentration of the ionic species in the resin.

Plastiques — Résines époxy — Détermination de la conductivité électrique des extraits aqueux de résine

General Information

• Status: Published
• Publication Date: 23-Jan-2007
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: ISO/TC 61/SC 12 - Thermosetting materials
• Drafting Committee: ISO/TC 61/SC 12/WG 5 - Unsaturated polyesters, epoxy resins and other resins
• Current Stage: 9060 - Close of review
• Completion Date: 04-Mar-2031

Relations

• Consolidated By: ISO 8536-11:2015 - Infusion equipment for medical use - Part 11: Infusion filters for single use with pressure infusion equipment
• Effective Date: 06-Jun-2022

Overview

ISO 21318:2007 specifies a standardized test method for determining the electrical conductivity of aqueous extracts of epoxy resins. The method measures ionic species in an extract produced by water extraction at 95 °C and is intended for epoxy resins that are molten at that temperature. The measured conductivity serves as an aggregate indicator of ionic impurities (e.g., chloride, sodium, catalyst residues) that can impair epoxy insulation in electronic devices.

Key topics and technical requirements

• Scope: Applicable only to epoxy resins molten at 95 °C; used primarily for electronic insulation materials.
• Extraction conditions: Test portion 8.00 g ± 0.05 g with 80 ml ± 2 ml distilled/deionized water (conductivity < 2.0 µS/cm) in a sealed HDPE bottle; heated at 95 °C ± 3 °C.
• Timing and safety: Loosen cap after 30 min to relieve pressure; total extraction time 20 h ± 0.5 h; use protective equipment when releasing pressure.
• Measurement: Measure extract conductivity at 25 °C using a conductivity meter accurate to 0.1 µS/cm with temperature compensation.
• Result expression: Corrected conductivity = sample conductivity − blank conductivity (expressed in µS/cm). Perform a blank test using the same water without resin.
• Precision: Repeatability and reproducibility data were established in a multi-laboratory trial (see standard for tabulated values).
• Reporting: Test report must reference ISO 21318, identify the sample, record results and date, and note any relevant influences on the result.

Practical applications and users

ISO 21318:2007 is practical for:

• Epoxy resin producers performing routine quality control to monitor ionic impurity levels.
• Electronics manufacturers specifying resin acceptance criteria for insulating encapsulants, potting compounds and coatings.
• Independent testing laboratories conducting material qualification and failure analysis.
• R&D and materials engineers assessing formulation or curing changes that affect ionic contamination.

Benefits include a simple, reproducible proxy measurement for overall ionic content, helping to reduce field failures due to conductive contamination in electronic assemblies.

Related standards

• ISO 5725-2 - Accuracy (trueness and precision) of measurement methods and results: basic method for determination of repeatability and reproducibility (referenced for precision data in ISO 21318).
• ISO/TC 61 - Technical committee responsible for plastics standards (development context).

Keywords: ISO 21318:2007, epoxy resins, electrical conductivity, aqueous resin extracts, ionic impurities, electronic insulation, conductivity meter, quality control.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 21318
First edition
2007-02-01
Plastics — Epoxy resins — Determination
of electrical conductivity of aqueous
resin extracts
Plastiques — Résines époxy — Détermination de la conductivité
électrique des extraits aqueux de résine

Reference number
©
ISO 2007
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ii © ISO 2007 – All rights reserved

Foreword
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(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
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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 21318 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting
materials.
Introduction
Where epoxy resins are used as insulation for electronic devices, ionic impurities such as chloride, sodium
and catalyst residues present in the epoxy resin can cause failure of the device. Instead of determining these
impurities separately, a test method may be used to evaluate their contents as a whole by measuring the
electrical conductivity of a resin extract obtained by extraction of the resin with water at an elevated
temperature. Because of its practical usage and simplicity, this method is becoming widely used in the quality
control of epoxy resins for electronic insulation applications.

iv © ISO 2007 – All rights reserved

INTERNATIONAL STANDARD ISO 21318:2007(E)

Plastics — Epoxy resins — Determination of electrical
conductivity of aqueous resin extracts
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