4.2 Solder Fume Extraction

Flux fumes are not merely an olfactory nuisance; they are a complex aerosol of colophony (rosin) particulates and gaseous byproducts capable of inducing permanent respiratory sensitization (occupational asthma). Treat fume extraction as a critical utility, equivalent to power or compressed air. If the capture velocity at the source is insufficient, the system is functionally offline, regardless of the fan motor's RPM.

Extraction Architecture

Select the extraction topology based on the specific thermal process and generation rate.

• If Process is Precision Hand Soldering -> Then deploy Tip Extraction (High Vacuum).
  • Physics: Captures fumes at the exact point of generation before thermal plumes disperse them.
  • Constraint: Requires daily maintenance to prevent tip clogging and reduced heat transfer.
• If Process is General Assembly/Rework -> Then deploy Volume Extraction (Articulated Arm).
  • Physics: Relies on high airflow volume to overcome ambient air currents.
  • Constraint: Hood placement is non-negotiable. Intake must be within 1.5x duct diameter of the solder joint. Distance follows the inverse square law; doubling the distance reduces capture efficiency by ~75%.
• If Process is Automated (Reflow/Wave) -> Then hard-duct to Central Facility Exhaust.
  • Constraint: Monitor differential pressure (∆P) across the duct to detect residue buildup (flux condensate).

Pro-Tip: Flux fumes are hot and rise naturally. Position extraction hoods slightly above and behind the workpiece to leverage the thermal plume, rather than fighting gravity with side-drafts.

Filtration Staging

For recirculating units, a single filter stage is insufficient. The system requires a progressive filtration stack to prevent early failure of expensive media.

Stage 1: Pre-Filter (Sacrificial)

• Function: Captures visible dust and large flux droplets.
• Action: Inspect weekly; replace Monthly. Failure here destroys the HEPA filter.

Stage 2: HEPA (Particulate)

• Function: Arrests 99.97% of particulates ≥ 0.3 µm (respirable fraction).
• Action: Replace every 6 – 12 months or when airflow drops below 0.5 m/s.

Stage 3: Activated Carbon (Gas)

• Function: Adsorbs VOCs and chemical odors.
• Action: Replace immediately upon detecting odor breakthrough or saturation alarm.

Final Checklist