Overview
EN ISO 9455-15:2017 - Soft soldering fluxes: Copper corrosion test (ISO 9455-15:2017) specifies a qualitative test method to determine the corrosive properties of flux residues on a copper substrate under controlled environmental conditions. The procedure is intended for type 1 fluxes (as defined in ISO 9454‑1) and is adopted by CEN as a European standard. The test helps assess whether flux residues promote copper corrosion after soldering and environmental exposure.
Key Topics
- Test principle: A solder pellet is melted in contact with the flux on a prepared copper test piece; the specimen is conditioned in a controlled temperature/humidity environment and inspected microscopically for corrosion.
- Scope and applicability: Applies to type 1 soft soldering fluxes; updated to include lead‑free solders in the 2017 revision.
- Sample preparation:
- 0.5 mm phosphorus‑deoxidized copper sheet cut to 50 × 50 mm and cupped to a 3 mm depression.
- Cleaning sequence: degreasing solvent, sulfuric acid treatment, ammonium peroxodisulfate etch, rinses and drying (detailed in the standard).
- Reagents and materials: ammonium peroxodisulfate solution, 5 % sulfuric acid, neutral organic degreasing solvent, and specified solder alloys (e.g., Sn63Pb37, Sn60Pb40, Sn96.5Ag3Cu0.5) or other agreed alloys.
- Apparatus and conditions:
- Solder bath (specified temperatures per alloy),
- Humidity chamber conforming to IEC 60068‑2‑78 (test Cab damp heat steady state),
- Cupping device, drying oven (60 °C), and a low‑power stereomicroscope (×20 magnification).
- Assessment and reporting: Visual/microscopic assessment of corrosion after fluxing, melting and conditioning; results expressed qualitatively and recorded in a test report.
Applications
- Flux manufacturers: product development and quality control to ensure flux residues are non‑corrosive on copper.
- Solder and electronic assembly suppliers: qualification of flux/solder combinations, especially for lead‑free processes.
- Quality assurance and testing laboratories: environmental exposure testing, corrosion evaluation, and failure analysis.
- Electronics and PCB manufacturers: selecting flux systems to minimize post‑assembly copper corrosion and reliability risks.
Benefits include improved process control, reduced field failures from corrosive residues, and evidence for materials selection and supplier agreements.
Related Standards
Keywords: EN ISO 9455-15:2017, soft soldering fluxes, copper corrosion test, flux residues, type 1 fluxes, soldering flux testing, lead-free solder evaluation, humidity chamber, IEC 60068-2-78.
