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Flux plays an essential role in electronics assembly, helping to remove oxidation from metal surfaces and allowing solder to flow effectively, contributing to reliable electrical connections. However, the heating process can release contaminants into the air, making effective exposure control an important consideration.
© sergey Kolesnikov / Shutterstock.com
For workplaces where soldering is carried out regularly, understanding the risks of flux fumes is an important part of managing occupational health and safety. The level of risk will depend on factors including the formulation, soldering processes, how frequently the work is performed and how effectively emissions are controlled.
Solder fume extraction is vital in electronics processing. Properly designed, it can capture contaminants close to source, reducing the amount that reaches the operator’s breathing zone or spreads throughout the workplace.
Hazardous fumes are produced when flux is heated during soldering. Their composition depends on the formulation and the temperature and conditions of the process.
Rosin or colophony-based fluxes are particularly significant. The UK Health and Safety Executive identifies rosin-based flux fumes as a common cause of occupational asthma. The HSE also notes contact with solder fumes and residues can contribute to skin problems, such as dermatitis.
The fumes contain both particulate and vapour components. Rosin-based flux fumes contain sublimates and thermal decomposition products, alongside lower molecular weight compounds in the vapour.
Whether solder fumes present a significant health risk depends on the materials being used, the soldering process and the level of exposure. The issue isn’t whether a worker experiences an immediate reaction to visible fumes; repeated occupational exposure can impact long-term health, particularly where soldering takes place for extended periods without effective control.
Other materials can introduce additional hazards. For example, solder containing lead presents different risks, while some coated components or other materials used in electronics processing may produce their own emissions when heated. Consequently, a proper risk assessment should always start with the actual materials and processes used, rather than making assumptions about “solder fumes” as a single substance.
The principal concern is inhalation. Where fumes enter an operator’s breathing zone, workers may be exposed directly before contaminants are captured or dispersed. The HSE recommends monitoring how often and for how long employees and other people nearby could also be exposed. This is particularly relevant in busy electronics facilities.
A production area may contain many soldering stations working simultaneously, so emissions can become a workplace-wide issue, rather than something confined to an individual bench. Poor positioning can make matters worse. If a worker leans directly over a soldering point, fumes can travel straight into the breathing zone before they disperse. General ventilation may improve overall room air quality, but may not provide adequate control at the point where fumes are generated.
Visible flux smoke should not be treated as an inevitable part of soldering or allowed to accumulate in the workplace. The amount of smoke can vary, but its apparent absence doesn’t provide a reliable indication of the amount of airborne exposure, as some contaminants can’t be seen by the naked eye and once released, fumes can be carried by air movement around the workspace, creating hazards for everyone in an enclosed production environment.
The basic principle behind solder fume extraction is straightforward: capture contaminants as close to their source as reasonably practicable. A suitable local exhaust ventilation system draws contaminated air away before it reaches the operator’s breathing zone. This could involve extraction close to an individual soldering point, a ventilated workstation, or a larger extraction arrangement designed around the production process.
Effective extraction depends on achieving sufficient capture at the source. A capture point positioned too far from the soldering operation may not collect fumes effectively, while a system that does not suit the volume or characteristics of the emissions may not provide the required control.
HSE guidance on rosin-based solder flux fumes supports the use of effective engineering controls as part of controlling exposure under COSHH regulations.
There’s no single extraction solution that is automatically right for every electronics facility, as the processes and workplace need to be considered together. The number of soldering stations is an obvious starting point. A single repair bench has different requirements from a production area with several operators soldering continuously.
Hand soldering, rework, desoldering and other processes can generate different quantities and characteristics of fumes. The materials being used should also be considered, including the specific flux and solder formulations.
Workspace layout is another important factor. Where operators work at fixed benches, a workstation-based extraction solution may be appropriate. Where processes move around or require greater flexibility, a different arrangement may be more suitable. The position of the operator, the location of neighbouring workstations, available floor space and the way clean and contaminated air moves through the area can all affect the eventual design.
AirBench has developed extraction solutions for manufacturing environments where dust and fumes need to be captured during manual processes. The range includes downdraught benches and other systems designed around different workplace applications.
Electronics manufacturing usually requires downdraught extraction equipment, including solder fume extraction and PCB-related processes. The system is designed to draw contaminants through the work surface and into filtration, with filter selection matched to the application.
For electronics processing, the value of a downdraught approach is that extraction can be integrated into the workstation itself, rather than relying on an operator to position a separate extraction arm correctly. The work surface can provide a defined capture area. Broader fume extraction systems can form part of a wider workplace strategy, including cross-draught systems and air-cleaning solutions designed for different industrial applications.
Under COSHH, employers are required to assess exposure to hazardous substances and take appropriate steps to prevent or adequately control that exposure. Extraction equipment also needs to remain effective over time: a system that was effective when first installed cannot simply be assumed to remain effective indefinitely. Filters, airflow and other components require appropriate inspection and maintenance, while operators need continual training to understand how the system must be used.
Ultimately, good extraction should work alongside sensible process controls, maintenance, training and COSHH management.
AirBench Ltd are the UK’s leading manufacturer of downdraught benches and cross draught extraction systems. We have more than 10,000 extraction systems in service in the UK and overseas. Along with our range of coolant mist filters and air cleaning systems, we are actively helping businesses across many industries solve their workplace dust and fume issues.
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If you’d like to try an AirBench product for FREE simply book a demo and we’ll bring one to you.