Printed Circuit Boards contain a large number of electronic components that are held on the board by solidified solder flux. Soldering is the process used to install components on a PCB while desoldering is performed when a component is to be removed from the board. Since soldering and desoldering involve melting the solder flux, there are hazards associated with these processes.
In order to melt the solder flux for soldering or desoldering, its temperature must be raised to a high value, on the order of 400 degrees Celsius. This is generally done with the help of a soldering iron whose tip is raised to that temperature. When this heated tip is brought in contact with the solid solder, it melts it immediately. Extreme care is required while handling the soldering iron since if its tip touches the skin it can cause serious burns.
Solder Flux Fumes
As the solder flux is raised to a high temperature while soldering or desoldering, some of it evaporates into the air. The resin acid particulates produced during this process are harmful for health. If inhaled, these particles can cause occupational asthma or worsen existing asthma. If a person is exposed to these fumes for an extended period of time, the asthmatic effects may become irreversible.
Particles can also cause eye irritation and, in case of extreme exposure, eye damage can occur. Always work in well ventilated areas and wear eye protection while soldering or desoldering.
Solder Flux Skin Exposure
The solder flux in a molten state can cause damage to skin. Since the flux contains irritants as well as sensitisers, it may cause dermatitis. Skin damage from flux fumes is rare, though it can happen in case of extreme exposure. Generally, skin damage occurs when molten flux sputters on the skin during the soldering or desoldering process. In this case the skin can get damaged due not only to chemical reactions but also due to the high temperature of the flux.
Solder Flux Lead Exposure
Though lead-free solder flux is now commonly available, the regular flux is still in widespread use. If the solder is raised to a temperature higher than 450 degrees Celsius, some of the lead particles may be carried in air with flux fumes. Inhaling these particles can cause serious breathing issues and long term exposure can have detrimental health effects. Therefore lead-free flux should always be preferred and, if it is not available, the temperature of the solder flux should not be increased to a value higher than 450 degrees Celsius.