ISO 9455-16:2019 PDF

Soft soldering fluxes — Test methods — Part 16: Flux efficacy test, wetting balance method

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Title (English):

ISO 9455-16:2019

Soft soldering fluxes — Test methods — Part 16: Flux efficacy test, wetting balance method

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 19
Publication date:: September 18, 2019
Edition:: ISO IS 9455 edition 3 version 1
ICS:: 25.160.50

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Description (English):

This document specifies a method for the assessment of the efficacy of a soft soldering flux, known as the wetting balance method. It gives a qualitative assessment of the comparative efficacy of two fluxes (for example, a standard and a test flux), based on their capacity to promote wetting of a metal surface by liquid solder. The method is applicable to all flux types in liquid form classified in ISO 9454‑1. NOTE It is hoped that future developments using improved techniques for obtaining a reproducible range of test surfaces will enable this method for assessing flux efficacy to be quantitative. For this reason, several alternative procedures for preparing the surface of the test piece are included in the present method.

Technical details

Technical committee: ISO/TC 44/SC 12 - Soldering materials
SKU: ISO 9455-16:2019

Abstract

Overview

ISO 9455-16:2019 specifies a standardized flux efficacy test using the wetting balance method to assess how well a liquid soft-soldering flux promotes wetting of a metal surface by molten solder. The method provides a qualitative comparative assessment between a test flux and a standard flux (for example, a reference rosin-based flux). It applies to all liquid flux types classified in ISO 9454-1 and is intended for laboratory evaluation of flux performance under controlled surface and environmental conditions.

Key Topics and Requirements

Test principle: Measure wetting force vs time using a wetting balance; compare test flux performance to a standard flux.
Scope: Applicable to liquid fluxes classified in ISO 9454-1; current method is comparative (qualitative) though provisions exist for reproducible surface preparation to move toward quantitative use.
Apparatus: Wetting balance and instrumentation in accordance with IEC 60068-2-69; solder bath capable of maintaining liquidus + 35 °C.
Solder alloys and temperatures: Examples provided include Sn60Pb40 at 235 °C ± 3 °C and Sn96.5Ag3.0Cu0.5 at 255 °C ± 3 °C; other combinations possible by agreement.
Test pieces: Copper strips (typical width 10.0 mm ± 0.1 mm; thickness 0.10 mm or 0.30 mm); clean, burr-free, handled with clean tongs.
Surface preparation / ageing: Multiple options to simulate realistic or contaminated surfaces:
- Artificial sulfidation (Annex B)
- Steam ageing (per IEC 60068-2-20)
- Damp-heat steady-state ageing (per IEC 60068-2-78)
Procedure highlights:
- Clean test pieces (acid clean, rinses, acetone)
- Apply flux, allow solvent evaporation (typical drying 20 s ± 5 s, adjustable by agreement)
- Immerse at 20 mm/s ± 5 mm/s to 3 mm ± 0.2 mm or 4 mm ± 0.2 mm depth, hold 5–10 s, withdraw at same speed
- Record wetting-force trace; perform 10 replicates per flux and complete within 45 minutes of preparation
Results: Typical trace shows wetting force vs time; analysis compares characteristic wetting times and forces against the standard flux prepared per Annex A.

Applications and Users

Who uses it: flux manufacturers, solder material suppliers, electronics manufacturing engineers, quality assurance labs, and R&D teams developing or qualifying soft soldering fluxes.
Practical uses:
- Comparative evaluation of new flux formulations
- Incoming inspection and supplier qualification
- Process development for wave or selective soldering where flux wetting behavior is critical
- Failure analysis to determine flux-related wetting deficiencies

Related Standards

ISO 9454-1 - Classification and requirements for soft soldering fluxes
IEC 60068-2-69 - Wetting balance (force measurement) method
IEC 60068-2-20 - Steam ageing (solderability tests)
IEC 60068-2-78 - Damp-heat steady-state ageing
ISO 9453 - Solder alloy composition references

Keywords: ISO 9455-16:2019, wetting balance method, flux efficacy test, soft soldering fluxes, solderability, ISO 9454-1.

Related standards

Standards mentioned in the description

Abstract

Overview

Key Topics and Requirements

Test principle: Measure wetting force vs time using a wetting balance; compare test flux performance to a standard flux.
Scope: Applicable to liquid fluxes classified in ISO 9454-1; current method is comparative (qualitative) though provisions exist for reproducible surface preparation to move toward quantitative use.
Apparatus: Wetting balance and instrumentation in accordance with IEC 60068-2-69; solder bath capable of maintaining liquidus + 35 °C.
Solder alloys and temperatures: Examples provided include Sn60Pb40 at 235 °C ± 3 °C and Sn96.5Ag3.0Cu0.5 at 255 °C ± 3 °C; other combinations possible by agreement.
Test pieces: Copper strips (typical width 10.0 mm ± 0.1 mm; thickness 0.10 mm or 0.30 mm); clean, burr-free, handled with clean tongs.
Surface preparation / ageing: Multiple options to simulate realistic or contaminated surfaces:
- Artificial sulfidation (Annex B)
- Steam ageing (per IEC 60068-2-20)
- Damp-heat steady-state ageing (per IEC 60068-2-78)
Procedure highlights:
- Clean test pieces (acid clean, rinses, acetone)
- Apply flux, allow solvent evaporation (typical drying 20 s ± 5 s, adjustable by agreement)
- Immerse at 20 mm/s ± 5 mm/s to 3 mm ± 0.2 mm or 4 mm ± 0.2 mm depth, hold 5–10 s, withdraw at same speed
- Record wetting-force trace; perform 10 replicates per flux and complete within 45 minutes of preparation
Results: Typical trace shows wetting force vs time; analysis compares characteristic wetting times and forces against the standard flux prepared per Annex A.

Applications and Users

Who uses it: flux manufacturers, solder material suppliers, electronics manufacturing engineers, quality assurance labs, and R&D teams developing or qualifying soft soldering fluxes.
Practical uses:
- Comparative evaluation of new flux formulations
- Incoming inspection and supplier qualification
- Process development for wave or selective soldering where flux wetting behavior is critical
- Failure analysis to determine flux-related wetting deficiencies

Related Standards

ISO 9454-1 - Classification and requirements for soft soldering fluxes
IEC 60068-2-69 - Wetting balance (force measurement) method
IEC 60068-2-20 - Steam ageing (solderability tests)
IEC 60068-2-78 - Damp-heat steady-state ageing
ISO 9453 - Solder alloy composition references

Keywords: ISO 9455-16:2019, wetting balance method, flux efficacy test, soft soldering fluxes, solderability, ISO 9454-1.

ISO 9455-16:2019 PDF

Technical details

Abstract

Overview

Key Topics and Requirements

Applications and Users

Related Standards

Related standards

Abstract

Overview

Key Topics and Requirements

Applications and Users

Related Standards

Related standards

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