Overview
EN ISO 9454-2:2020 - Soft soldering fluxes: Part 2 - Performance requirements (ISO 9454-2:2020) specifies performance criteria for fluxes in solid, liquid and paste forms intended for use with soft solders. Adopted by CEN as a European Standard, it defines the properties, test methods and minimum performance levels fluxes must meet when evaluated using the ISO 9455 test series.
Key topics and technical requirements
- Scope and flux condition: Solid fluxes must be uniform and free from deleterious contaminants; liquid fluxes must be homogeneous and free from sediment; paste fluxes must have consistent, application‑suitable viscosity.
- Classification linkage: Performance requirements complement the labelling, packaging and coding rules set out in ISO 9454‑1.
- Performance criteria (Tables 1–3): Numeric and pass/fail requirements are specified for different flux types (e.g., rosin‑based, modified rosins, organic/non‑rosin), activation levels and grades. Criteria include:
- Non‑volatile content and tolerances
- Acid value (expressed in mg KOH/g) - measured per ISO 9455‑3
- Halide content (chloride/bromide/iodide) - ISO 9455‑6 methods
- Solder spread tests (area and spread ratio) - ISO 9455‑10
- Copper mirror and chromate silver paper tests - assessing corrosive residues
- Solubility of residues, spattering, tackiness, and copper/steel corrosion tests (various ISO 9455 parts)
- Special cases: Fluxes intended for inert gas or vapour‑phase soldering may not meet all table criteria; requirements for these products should be agreed between purchaser and supplier.
Applications and practical value
- Ensures consistent performance and safety of fluxes used in soft soldering operations.
- Helps manufacturers and suppliers demonstrate compliance through standardized test methods and measurable limits.
- Supports material selection for production and repair: choosing fluxes with acceptable residue behaviour, low corrosion risk and reliable wetting.
- Aids procurement and quality assurance teams in specifying flux properties in tenders and technical orders.
Who uses this standard
- Flux and solder manufacturers
- Electronics assemblers and OEMs
- Procurement, quality and compliance engineers
- Test laboratories and certification bodies
- Designers and process engineers defining soldering procedures
Related standards
Keywords: EN ISO 9454-2:2020, soft soldering fluxes, flux performance requirements, solder flux testing, ISO 9455, acid value, halide content, solder spread test, flux residue solubility.
