Norm - this there any published data on this degradation mechanism? Dave Hillman Rockwell Collins [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Re: GEN: Heat - Sealing? Author: [log in to unmask] at ccmgw1 Date: 5/13/96 2:52 PM Heat sealing of plastic bags creates a gas. This gas gets trapped in the bag and adversely works on the tin (not the lead). Doesn't help popcorning because once you open the bag, moisture is back into the board material in less than 24 hours. Baking the boards within 3 to 4 hours just prior to soldering would help this. However, I don't advocate baking as this will diminish solderability. I don't advocate heal sealing either as this shortens solerability. Simply fold over the end of the bag and tape it shut. As for components losing solderability due to heat sealing, I would suspect you have the same problem here as the leads have a tin coating. Requires investigative work on someone out there. Regards, Norm Einarson