Thereis no good way to calculate lead (Pb) particulate from your selective solderingprocess as there are far too many variables. It depends on the jetor wave temperature, solder jet or wave surface area, turbulence of liquidsolder, turbulence of air around the jetting or wave process, exhaust flow,exhaust flow turbulence, inert gas volume if there is inert gas in your process,solder alloy, even air temperature. These are just a few of thevariables. Open a door or window to the outside and everythingchanges.
Ifyou have a steady-state process (controlled and repeatable conditions), thenyou can do some basic air sampling as with Draeger tubes or other environmentalmonitoring system and get estimates of Pb particulate in and around theselective soldering operation. There are many online guides to airsampling. This one has some basic guidelines: http://www.health.ny.gov/environmental/indoors/air/guidance.htm
It is critically important that the process isexhausted and that the exhaust is sized appropriately. Ensure thatoperators are versed in the dangers of handling Pb or Pb-bearing alloys andalso aware of Pb-particulate environment. Also ensure that you are incompliance with State and Federal environmental statutes.
Gary Freedman
President
Colab Engineering
A thirty year veteran of electronics assembly with major OEMs including Digital Equipment Corp., Compaq and Hewlett-Packard. President of Colab Engineering, LLC; a consulting agency specializing in electronics manufacturing, root-cause analysis and manufacturing improvement. Holder of six U.S. process patents. Authored several sections and chapters on circuit assembly for industry handbooks. Wrote a treatise on laser soldering for Laser Institute of America's LIA Handbook of Laser Materials Processing. Diverse background includes significant stints and contributions in electrochemistry, photovoltaics, silicon crystal growth and laser processing prior to entering the world of PCAs. Member of SMTA. Member of the Technical Journal Committee of the Surface Mount Technology Association.
|
