SIST EN ISO 9455-16:2020 PDF

Overview

EN ISO 9455-16:2019 - "Soft soldering fluxes - Test methods - Part 16: Flux efficacy test, wetting balance method" defines a laboratory procedure for assessing the efficacy of liquid soft‑solder fluxes using the wetting balance (force‑measurement) technique. The method gives a qualitative comparative assessment between a standard flux and a test flux based on their ability to promote wetting of a metal surface by liquid solder. It applies to all liquid flux types classified in ISO 9454‑1.

Key topics and requirements

• Test principle: Measurement of wetting force over time (wetting balance) to compare flux performance.
• Scope: Qualitative comparison; provisions included for several surface‑preparation options to improve reproducibility. The standard notes potential for future quantitative developments.
• Apparatus: Wetting balance and ancillary instrumentation in accordance with IEC 60068‑2‑69; a solder bath capable of maintaining the alloy liquidus temperature plus 35 °C; appropriate calibration and bath dimensions.
• Solder alloys and temperatures: Example alloys and test temperatures specified (e.g., Sn60Pb40 at 235 °C ± 3 °C, Sn96.5Ag3.0Cu0.5 at 255 °C ± 3 °C) or customer‑agreed combinations.
• Test pieces: Copper test strips with defined dimensions (typical: 10.0 mm width, length 15–30 mm, thickness 0.10 mm or 0.30 mm) and controlled surface condition.
• Surface preparation: Cleaning, artificial sulfidation, steam ageing and damp‑heat steady‑state ageing methods are included to simulate different contamination/ageing states.
• Reagents and cleanliness: Use of analytical‑grade reagents (acid cleaning solution, acetone, isopropyl alcohol) and acid‑free filter paper.
• Results and reporting: Time‑based wetting traces, reference values using a standard flux, calculation and presentation requirements for comparative efficacy; full test report content specified.

Applications and users

This standard is intended for:

• Flux manufacturers evaluating product performance and conformity.
• Independent test laboratories performing solderability and flux efficacy testing.
• Process and quality engineers in electronics assembly, PCB manufacturing, and soldering R&D who need to compare fluxes or validate cleaning/fluxing strategies.
• Procurement and qualification teams using a standardized comparative method for supplier evaluation.

Practical benefits include standardized comparison of wetting behaviour, guidance on controlled surface preconditioning, and repeatable lab protocols for routine quality checks and product development.

Related standards

• ISO 9454‑1 - Classification and requirements for soft soldering fluxes (labelling/packaging)
• IEC 60068‑2‑69 - Wetting balance (force measurement) method
• IEC 60068‑2‑20, IEC 60068‑2‑78 - Environmental and solderability test methods
• ISO 9453 - Solder alloy specifications

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