ISO 9455-6:2022

Overview

ISO 9455-6:2022 specifies test methods for the determination and detection of ionic halide (excluding fluoride) content in soft soldering fluxes. Halides are reported as chlorides. The standard defines three quantitative titration procedures (Methods A, B, C) and one qualitative detection test (Method D), covering a wide range of flux chemistries and practical laboratory requirements.

Key topics

• Scope and reporting
  • Ionic halides (chloride equivalent) only; fluoride excluded.
  • Results can be expressed as percentage by mass in the flux or in the non‑volatile matter.
• Method A - Potentiometric titration (reference method)
  • Uses silver nitrate (0.02 mol/L) titrant and a silver electrode with a suitable reference electrode (mercury/mercurous sulfate or reversible hydrogen).
  • Applicable to flux classes 1 and 2 (per ISO 9454-1).
  • Suitable for typical halide ranges (generally 0.05 % to 2 % mass fraction in non‑volatile matter); procedure commonly targets ~0.1 % to 1 % and prescribes sample mass adjustments outside this range.
  • Involves plotting potential (mV) vs titrant volume, determining inflection point and calculating percentage using provided formulae and a correlation factor (f) from standardization.
• Method B - Titration for water‑soluble fluxes
  • Designed for total halide determination in water‑soluble fluxes (flux classes 2122–2124, 3112–3114, 3212–3214).
  • Uses silver nitrate followed by back‑titration with ammonium thiocyanate; includes blank correction.
• Method C - Titration for phosphate‑containing water‑soluble fluxes
  • Specific procedure for flux class 331 (phosphate‑containing).
  • Similar titrimetric approach with reagent adjustments to account for phosphates.
• Method D - Qualitative detection
  • Rapid screening using silver chromate test paper for the presence of ionic halides; applicable to all flux classes.
• Quality control aspects
  • Use of analytical‑grade reagents, deionized water, blank determinations, triplicate testing (Method A) and standardization (Annex A for silver nitrate).

Applications and users

ISO 9455-6:2022 is used by:

• Solder flux manufacturers for product characterization and quality control
• Independent testing laboratories and R&D teams validating flux chemistry
• Electronics assemblers and QA teams verifying flux acceptability and process compatibility
• Procurement and compliance specialists requiring documented test methods for specifications

Practical benefits include reliable quantification of ionic halides (critical for corrosion and solderability performance), consistent reporting across suppliers, and fast screening tools for production environments.

Related standards

• ISO 9454-1 - flux classification (referenced for applicability of methods)
• ISO 9455-1 / ISO 9455-2 - determination of non‑volatile matter (used when reporting halides in non‑volatile content)
• Annex A of ISO 9455-6 - method for standardizing silver nitrate solution

Keywords: ISO 9455-6:2022, soft soldering fluxes, halide content, potentiometric titration, silver nitrate, ammonium thiocyanate, silver chromate, ISO 9454-1, flux testing, solder flux QC.