4.2 Solder Fume Extraction

SolderingFlux processesfumes generateare not merely an olfactory nuisance; they are a complex aerosol of colophony (rosin) particulates and gaseous byproducts,byproducts whichcapable areof potentinducing permanent respiratory sensitizerssensitization (causes of occupational asthma). EffectiveTreat Localfume Exhaustextraction Ventilationas (LEV)a critical utility, equivalent to power or compressed air. If the capture velocity at the source is ainsufficient, legalthe system is functionally offline, regardless of the fan motor's RPM.

Extraction Architecture

Select the extraction topology based on the specific thermal process and healthgeneration mandate.

Extraction Hierarchy

rate.

• If Process is Precision Hand Soldering -> Then deploy Tip Extraction (High Vacuum): A small tube integrated directly onto the soldering iron. .
  • Pros:Physics: Captures fumes at the source.exact point of generation before thermal plumes disperse them.
  • Cons:Constraint: CanRequires cooldaily themaintenance tip;to highprevent maintenance.tip clogging and reduced heat transfer.
• Arm/CowlingIf Process is General Assembly/Rework -> Then deploy Volume Extraction (Volume):Articulated Arm) Flexible arms positioned near the work. .
  • Mandate:Physics: TheRelies hoodon high airflow volume to overcome ambient air currents.
  • Constraint: Hood placement is non-negotiable. Intake must be within 1.5x the duct diameter of the solder jointjoint. Distance follows the inverse square law; doubling the distance reduces capture efficiency by ~75%.
• If Process is Automated (Reflow/Wave) -> Then hard-duct to beCentral effective.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 MachineMonthly. Extraction: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 Reflow ovens and Wave soldering machines must be ducted directly to the facility exhaust or heavy-dutywhen filtrationairflow units.drops below 0.5 m/s.

FiltrationStage Maintenance3:

Activated

Recirculating unitsCarbon (which return air to the room) must use a multi-stage system:Gas)

• Pre-Filter: Captures large dust (Change Monthly).
• HEPA Filter: Captures particulates > 0.3 micron (Change every 6-12 months).
• Activated Carbon/Gas Filter:Function: Adsorbs VOCs and odorschemical (Changeodors.
• Action: whenReplace immediately upon detecting odor breakthrough or saturation alarm triggers or smell is detected).alarm.

Final Checklist

SystemParameter	RequirementMetric / Rule	MaintenanceCritical State
Capture Velocity	At Source	≥ 0.5 m/s at the source	Annual Flow Test
FilterHood IntegrityPosition	NoMax visible bypass; HEPA activeDistance	Logged≤ Change1.5x ScheduleDuct Diameter
DuctingDuct Pressure	Negative pressure (no leaks)Integrity	Negative (No Leaks)
Pre-Filter	VisualReplacement InspectionCycle	Monthly
HEPA Status	Efficiency	No Visible Bypass
System Check	Flow Test Frequency	Annual