The article referenced below by David is really good and really scary! The article can be downloaded but requires that you identify yourself so they can send by email a link to download the article. Look here and read down the list to the sixth article available for download: https://foresiteinc.com/resources/ Look for the article titled, "Low Voltage, the Incompetent Ignition Source – Dispelling the Myth." While this article is focused on problems resulting from use of no-clean solder fluxes commonly used today, note that activated rosin fluxes, if not thoroughly cleaned after soldering, leave the activation chemicals on the board. Larry On 5/14/2018 9:56 AM, Van Horn, David wrote: > There's a great article out there on the web. It takes a bit of digging, but the title is "Low voltage, the incompetent ignition source". > They discuss fires on PCBs caused by trace contaminants and dendrite growth. A PCB with sustained flame is shown, powered by a lithium coin cell.... -- Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland) -- Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland)