Joshua Evans MEng (Hons) IChemE, Applications Engineer and Head of BOFA Academy at BOFA International, highlights the importance of safety in the electronics industry.
Automated soldering processes have a significant and positive impact on productivity in the global electronics industry. However, what automation in electronics doesn’t necessarily do is to reduce all risks in any given process. While it can reduce manual contact, there are still steps that manufacturers need to consider as part of their workplace occupational health strategies to help address these potential risks.
This includes assessing the need for effective atmosphere management and investing in appropriate fume extraction and filtration systems. This is important for employers because the UK has strict rules in place governing exposure levels to potentially harmful airborne contaminants.
These protections are mandated through the COSHH (Control of Substances Hazardous to Health) regulations and expressed as workplace exposure limits (WELs). WELs are presented as time weighted averages for either 15 minutes or eight hours, in both ppm (parts per million) or mg/m3 (milligrams per metre cubed).
In weighing up the best approach to fume extraction in electronics, engineering along with health and safety managers need first to understand any potential health risk presented by a given process and then assess the installation and life cycle costs of fixed and portable extraction system options. This needs to be evaluated in the context of the mix of work relative to product volume, capacity and the need for agility. If they do not have the resources in-house, companies have the option to hire consultant Industrial Hygienists to assist them with this assessment.
Specifically, from an emissions perspective, this assessment needs to take account of the volume, size and chemical composition of particulate or fume emitted, paying particular attention to the potential toxicity of each substance and any resultant chemical interaction.
This will inform the design of the fume extraction system architecture, the filtration media used, the integration of sensors (for high temperature applications for example) and the most appropriate monitoring and control mechanisms.
Whereas the default position for electronics companies was once to hook up any new or changed process to a vent-to-air or centralised exhaust system, now portable extraction systems are gaining traction to support more agile working practices, as well as environmental strategies. The value of a flexible approach was underlined in manufacturing settings during the pandemic environment.
For the electronics sector, there are specific challenges to address.
If we look at wave soldering for example, here the printed circuit board components are placed on the board and passed over a continuous wave of molten solder. Areas not to be soldered are covered with a protective ‘mask’.
While this process doesn’t involve the resin/colophony present in hand soldering, which can present health risks, it can require the use of an alcohol-based solvent such as Isopropyl Alcohol (IPA) and a small amount of organic acid, fume from which needs to be managed, extracted and filtered.
Before soldering, the boards are ‘spray fluxed’, using either a general spray process, which can generate an airborne dispersion of the flux, or a targeted jet from a robotic nozzle. Either way, the airborne contaminants created can be controlled through effective atmosphere management, which includes investment in fume extraction technology.
With reflow soldering, solder paste is applied to the PCB and components are then ‘picked and placed’. The board moves through various heating, stabilising and cooling zones, during which the solder metal ‘reflows’ or melts and solidifies around the component connection. During this process, the solvent which makes the paste liquify will evaporate and this airborne emission can then be filtered through an extraction unit.
In addition, the fumes from this process will include rosin content, which can present a risk to health if not controlled. A solder flux may also be used, which is likely to possess a significant concentration of ammonium chloride. As with wave soldering, operating temperatures need to be considered to ensure the effective filtration of any potentially harmful emissions.
Portable fume extraction systems can contribute to compliant atmosphere management in process environments through multi-stage filtration technology that includes specialist activated carbon filters designed to filter specific types of chemical emissions.
This also helps protect equipment from a build-up of dust on critical components, which might otherwise impact on product quality, lead to rework or even result in production line downtime.