ISO/FDIS 9455-8

• Abstract:

  Describes the principle, the reagents and materials, the apparatus, the test procedure, the calculation of results, the precision and the contents of the test report.

• Status: Not Published
• ICS: 25.160.50 - Brazing and soldering
• Technical Committee: ISO/TC 44/SC 12 - Soldering materials
• Drafting Committee: ISO/TC 44/SC 12 - Soldering materials
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 10-Sep-2026
• Completion Date: 10-Sep-2026

• Consolidates: prEN ISO 9455-8 - Soft soldering fluxes - Test methods - Part 8: Determination of zinc content (ISO/FDIS 9455-8:2026)
• Effective Date: 12-Feb-2026
• Consolidates: ISO 13325:2019/Amd 1:2023 - Tyres — Coast-by methods for measurement of tyre-to-road sound emission — Amendment 1: Uncertainties
• Effective Date: 23-Aug-2025
• Revises: ISO 9455-8:1991 - Soft soldering fluxes — Test methods — Part 8: Determination of zinc content
• Effective Date: 09-Aug-2025

Overview

ISO/FDIS 9455-8: Soft soldering fluxes - Test methods - Part 8: Determination of zinc content is an international standard developed by ISO Technical Committee 44, Subcommittee 12. This standard outlines a precise analytical method for determining the zinc content in water-soluble soft soldering fluxes, particularly those containing approximately 25% zinc (as zinc chloride). The methodology encompasses the selection and preparation of reagents, the use of standard laboratory apparatus, procedural steps for titration, calculation of results, and requirements for comprehensive test reporting.

Ensuring accurate zinc content measurement in fluxes helps manufacturers, laboratories, and quality control professionals maintain product consistency and compliance with technical requirements. This standard plays a vital role in the electronics industry and other sectors that rely on soft soldering for component assembly.

Key Topics

• Scope and Applicability:

  • Applies to water-soluble fluxes, particularly of type 3 as defined in ISO 9454-1.
  • Suitable for flux solutions containing about 25% zinc (as zinc chloride); adjustment is necessary for samples with significantly different concentrations or solid fluxes.

• Test Method Principle:

  • An aqueous flux sample, combined with sulfuric acid and ammonium chloride, is made alkaline with ammonia. Any precipitated iron is removed.
  • The solution is titrated with a standardized EDTA solution, using Eriochrome Black T indicator to determine the zinc content.

• Essential Reagents and Materials:

  • Use of analytical grade chemicals including EDTA standard solution, buffer (pH 10), sulfuric acid, hydrochloric acid, ascorbic acid, ammonium chloride, and ammonia solution.
  • Only distilled or deionized water is specified.

• Apparatus:

  • Standard laboratory equipment, such as pipettes, volumetric flasks, beakers, and filtration materials.

• Procedural Steps:

  • Precise measurement and dilution of flux sample.
  • Controlled addition of reagents and removal of interfering elements (iron).
  • Careful titration under optimal lighting conditions for endpoint detection.

• Calculation and Reporting:

  • Formula for calculating zinc content as a percentage of zinc chloride.
  • Guidance on result interpretation and need for adjustments in case of sample variations.
  • Requirements for clear documentation in test reports.

• Precision:

  • Data from multi-laboratory tests on precision, emphasizing repeatability and reproducibility.

Applications

ISO/FDIS 9455-8 is critical for:

• Quality Assurance in Electronics Manufacture:
  Ensuring effective soldering by verifying flux composition, which directly impacts joint quality and reliability.

• Product Development and R&D:
  Supporting the development and validation of new flux formulations where zinc content is a key parameter.

• Regulatory and Standards Compliance:
  Facilitating compliance with international manufacturing and trade requirements concerning soldering materials.

• Laboratory Testing and Calibration:
  Providing an authoritative reference procedure for contract laboratories, calibration services, and third-party testing organizations.

Related Standards

For comprehensive flux characterization and consistent global practices, consider these related ISO standards:

• ISO 9454-1: Soft soldering fluxes - Classification and requirements - Part 1: Classification, labelling, and packaging
• ISO 9455-1: Determination of non-volatile matter, gravimetric method
• ISO 9455-3: Determination of acid value, potentiometric and visual titration methods
• ISO 9455-6: Determination of halide content
• ISO 9455-10: Flux efficacy tests, solder spread method

For further guidance, consult the complete ISO 9455 series and maintain alignment with the latest referenced editions.

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Keywords: soft soldering fluxes, zinc content determination, ISO 9455-8, soldering quality assurance, analytical test method, EDTA titration, electronics manufacturing standards, flux composition analysis.

FINAL DRAFT
International
Standard
ISO/TC 44/SC 12
Soft soldering fluxes — Test
Secretariat: DIN
methods —
Voting begins on:
2026-09-10
Part 8:
Determination of zinc content
Voting terminates on:
2026-12-03
Flux de brasage tendre — Méthodes d'essai —
Partie 8: Dosage du zinc
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 44/SC 12
Soft soldering fluxes — Test
Secretariat: DIN
methods —
Voting begins on:
Part 8:
Determination of zinc content
Voting terminates on:
Flux de brasage tendre — Méthodes d'essai —
Partie 8: Dosage du zinc
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Procedure . 2
8 Calculation of results . 3
9 Precision . 3
10 Test report . 3
Bibliography . 4

iii
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement. For an explanation of the voluntary nature of standards, the meaning of ISO
specific terms and expressions related to conformity assessment, as well a
...

ISO/TC 44/SC 12
Secretariat: DIN
Date: 2026-0608-26
Soft soldering fluxes — Test methods —
Part 8:
Determination of zinc content
Flux de brasage tendre — Méthodes d'essai —
Partie 8: Dosage du zinc
FDIS stage
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
E-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents
Foreword . iii
Scope . iii
Normative references . iii
Terms and definitions . iii
Principle. iii
Reagents . iii
Apparatus . iii
Procedure . iii
Calculation of results . iii
Precision . iii
Test report . iii
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Procedure . 2
8 Calculation of results . 3
9 Precision . 3
10 Test report . 3
Bibliography . 4

iii
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.
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.
International Standard ISO 9455-8The procedures used to develop this document and those intended for its
further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval
criteria needed for the different types of ISO document should be noted. This document was drafted in
accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement. For an explanation of the voluntary nature of standards, the meaning of ISO
specific terms and expressions related to conformity assessment, as well as information about ISO's adherence
to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 44, Welding and allied processes, Sub-
Committee SC 12, Soldering and brazing materials., in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 121, Welding and allied processes, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Th
...

PROJET FINAL
Norme
internationale
ISO/TC 44/SC 12
Flux de brasage tendre — Méthodes
Secrétariat: DIN
d'essai —
Début de vote:
2026-09-10
Partie 8:
Dosage du zinc
Vote clos le:
2026-12-03
Soft soldering fluxes — Test methods —
Part 8: Determination of zinc content
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
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INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
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SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
Numéro de référence
PROJET FINAL
Norme
internationale
ISO/TC 44/SC 12
Flux de brasage tendre — Méthodes
Secrétariat: DIN
d'essai —
Début de vote:
Partie 8: 2026-09-10
Dosage du zinc
Vote clos le:
2026-12-03
Soft soldering fluxes — Test methods —
Part 8: Determination of zinc content
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
DOCUMENT PROTÉGÉ PAR COPYRIGHT
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
© ISO 2026 INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
PROJETS DE NORMES
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INTERNATIONALES DOIVENT PARFOIS ÊTRE CONSIDÉRÉS
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
DU POINT DE VUE DE LEUR POSSI BILITÉ DE DEVENIR DES
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
NORMES POUVANT
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: [phone]
E-mail: [e-mail]
Web: www.iso.org
Publié en Suisse Numéro de référence
ii
Sommaire Page
Avant-propos .iv
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Principe. 1
5 Réactifs . 1
6 Appareillage . 2
7 Mode opératoire . 2
8 Calcul des résultats . 3
9 Fidélité . 3
10 Rapport d’essai . 3
Bibliographie . 4

iii
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