Overview
ISO 9455-11:2017 specifies a qualitative laboratory method for assessing the solubility of flux residues from Type 1 soft‑soldering fluxes in a selected solvent. The test evaluates whether a chosen cleaning solvent will effectively remove residues left after soldering by measuring electrical continuity across a cleaned brass test plate.
This standard is used to validate solvent selection, support cleaning process control and provide objective evidence of flux removal performance for manufacturers and quality laboratories.
Key Topics
- Principle: A fluxed brass test plate is soldered, conditioned, immersed in the selected solvent, then tested electrically. A steady full‑scale current indicates efficient residue removal.
- Test specimen: Brass test plates (60 mm × 60 mm, 0.5 mm, alloy CuZn37) with a central 3 mm depression.
- Apparatus highlights: solder bath (300 ± 10 °C), humidity oven (23 ± 2 °C, 50 ± 5 % RH), 6 V DC source, variable resistor (0–100 Ω), milliammeter (100 mA DC) and a 4 mm probe with Pd‑Ag tip.
- Reagents: analytical grade solvents, industrial methylated spirits and a specified acid cleaning solution for plate preparation.
- Procedure essentials: plates are fluxed, one plate is heated in the solder bath (plate A) and one left unheated (plate B), both conditioned, immersed in the selected solvent for the specified time, rinsed and dried, then reconditioned before electrical testing.
- Assessment: A steady full‑scale reading on the milliammeter when plate A is connected = pass. An unsteady or sub‑full reading = fail.
Applications
ISO 9455-11:2017 is practical for:
- Flux manufacturers validating recommended cleaning solvents for Type 1 fluxes.
- PCB and electronics assemblers verifying post‑solder cleaning processes and solvent effectiveness.
- Quality and R&D labs performing comparative screening of solvents and flux formulations.
- Procurement and supplier evaluation where documented evidence of residue removability is required.
Benefits include straightforward, reproducible qualitative assessment, alignment with ISO test series practices, and support for cleaner, more reliable solder joints when used alongside other cleanliness tests.
Related Standards
- ISO 9454-1: Classification and requirements for soft soldering fluxes (referenced normative document).
- Other parts of the ISO 9455 series: complementary test methods for soft soldering fluxes and residue evaluation.
For test reporting, ISO 9455-11 requires identification of the sample, reference to this method, the chosen solvent, immersion time used (e.g. 1 min or 10 min as applicable), results and any unusual observations. Use this method as part of an integrated flux qualification and cleaning validation program to help ensure reliable soldering outcomes.
