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Alcohol-based flux S-250/FRO

Recommended method of application
Wave soldering (spray fluxing)

No Clean-Flux, alcohol-based
Di-carboxylic acids, synthetic resin, halogenide-free (WEEE/RoHS compliant)
Type ISO-9454: 1231 // DIN EN 61190-1-1 1 (acc. J-STD-004) (IEC: REL0)

Cat.-No. 6400

Technical Data

Appearance/smell: colourless to light yellow, clear liquid
Hazardous goods: Yes
Solids content: 2.5 wt.-%
Acid number: 21 – 25 mg KOH/g
Halogenide-free: Yes
Resinous: Yes
Available as concentrate: No
Density at 20 °C: 0.794 (+/-0.003) g/ml
Flash point: 12 °C
Durability: 12 months


S-250/FRO is universally suitable for wave soldering. It is used successfully for a wide range of systems and wave types in both leaded and lead-free processes. Its high temperature stability and very good activity over a wide temperature range ensures a wide processing window with best soldering results. The surfaces are very clean after soldering, the SIR is above the standards. S-250/FRO is unsuitable for foam and spray fluxing and not recommended for selective and manual soldering (see also product matrix). Practice has shown, that no washing is needed for PCBA properly soldered with S-250/FRO. The IC test with needle adapters is generally not affected.

Customer added value

  • Very good soldering properties (capillarity, wetting)
  • Broad process window (very high thermal stability, good activity over a large interval)
  • Very good residue behaviour (very clean, high SIR)

Packaging units

Canister: 20 l