Otto's Original - Quality products since 1901


No clean, alcohol-based flux, synthetic resin,di-carboxylic
acids, halogen-free (WEEE/RoHS compliant)
ISO-9454: 1231 // DIN EN 61190-1-1: L0 (REL0)

Packaging units:
20 l
Application area: Wave soldering (spray fluxing)
Appearance/smell: colorless to light yellow, clear
Solids content: 2.5 Gew.-% (wt.-%)
Density at 20 °C: 0.794 (+/- 0.003) g/ml
Acid number: 21–25 mg KOH/g
Activators: di-carboxylic acids with synthetic resin
Solvents: short-chain alcohols
Flash point: 12 °C
Durability: 12 months
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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)

Questions about our products?
We will advise you by phone 06123 / 7046-0.