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Air Quality Monitoring for Flux in PCB Assembly

Dan Lewis

Hi All,

I have an interesting situation of which I have not come across before. We have multiple solder operation based areas within a clean room with what is 'believed to be' adequate LEV. Though often there is a flux-like smell coming from a reflow oven in an area not too far away from where operators sit.

I have equipment to measure the flow and static pressure of the extraction/ventilation system though I'm ideally looking for an air quality monitor that will be able to ensure compliance with COSHH regulations where I believe the [workplace exposure] limit of rosin-based solder flux fumes is set at 0.05mg/m³ (8hr TWA long term limit). I can find monitors which will read volatile organic compounds but when looking for something specific I can only find papers and documentation on the dangers and effects of flux inhalation.

I'm hoping that someone would be able to assist or point me in the right direction of someone who supplies specific equipment. I have contacted multiple measurement tool distributors who have been unable to help. I want to make sure that the areas are safe for operators in this heat whilst we also look at improving comfort by removing/filtering airborne particles causing the smell.

Many Thanks

  • +1

    air sampling can be done by placing test units "sniffers" with filter pads that are then inspected to see how much weight  they pick up in a given time, pumping at a known rate of litres per hour.These you normally hire from an air quality company for a week or whatever.

    It is possible to use ion drift spectroscopy for real time alarms but that is normally reserved for things rather more lethal than solder smoke. (think Porton Down...) Page 16-30 of this PDF describes how they work.

    At the low tech end, smoke matches (try BES or any other gas wholesalers) are handy to see where things are sucking from  and blowing to and if it all gets sucked up properly.

    The smell may well be vapours rather than particulates and may not show on a filter test. Activated charcoal may help if it air must be recirculated but easier to heat exchange with outside.

    Mike.

  • 0 in reply to mapj1

    Thanks Mike.

    I had no idea how it could be done and have testers for aerosols and outgassing from glues etc but not anything for this. Makes sense with the pads.

    I'm currently in talks with an air quality company and already have some budget equipment such as smoke pens for testing flow paths and air curtains on our furnaces.

    Really do appreciate the reply as I also didn't know about ion drift spectroscopy - every day is a school day.

  • 0

    As a bit of a side-track , ion beam spectroscopy is not expensive because it is hard, but because the market is very small and very military, and secure manufacture and calibration facilities are expensive.

    There have been a few almost DIY efforts that show that the technique is more or less within the reach of the well equipped private workshop, like this example from  the University of Basel. Although a few kV are needed to bias the drift tube, the current is negligible and the voltages more or less constant. Only the gate voltage needs pulsing, to less than 100V p-p and the response signatures are current pulses hundreds of microseconds wide after a mass and charge dependent drift time of perhaps 5-10 msec over  a few inches.


    Mike

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