Carl, I quit using "freeze cans" for troubleshooting because they did not work very well particularly on conformally coating products. When a "thermal failure" occurs it happens at a particular temperature or during a specific temperature change. Because polymers require much more time to change temperatures I discovered that freeze mist would "shoot by" or run past the thermal failure point. It would then require a long time to stabilize the circuit and try again. I used the EXair because I could control the temperature change by varying the distance from the nozzle to the circuit, had an endless supply of "cold", air and very little if any frost/moisture on the circuit. I discovered that 90% of the thermal failures could be "found" by recreating the thermal conditions at time of failure and gradually "bumping" the temperature around this point. I seldom had to go more than + 20 degrees C from the estimated thermal fail point to recreate the failure. Conformal coatings will "hold" joints in place until a certain thermal point is reached. Usually this is a "window" because as the coating dimensions change the joint will "make and break" contact. Hope this helps! David A. Douthit Manager LoCan LLC Carl VanWormer wrote: > According to the site: > http://www.emsdiasum.com/ems/clean/duster.html > The stuff I'm using claims "100% ozone-safe pressurized duster products". > > Since I turn the cans upside down (or refill my quick-freeze cans for a more > convenient spraying position), am I being more gentle to the environment? > If so, we can get down to the real question of "am I wrecking my electronics > systems by using quick-freeze for troubleshooting?" > > Carl Van Wormer > Cipher Systems > 1815 NW 169th Place, Suite 5010 > Beaverton, OR 97006 > Phone (503)-617-7447 Fax (503)-617-6550 > > -----Original Message----- > From: Brian Ellis [mailto:[log in to unmask]] > Sent: Friday, April 26, 2002 2:52 AM > To: [log in to unmask] > Subject: Re: [TN] Freeze Spray Trouble Shooting > > Bev > > I agree PFCs are the worst climate changers (with SF6) that exist. Some > of them are over 10,000 times worse than CO2. As a rule of thumb, 6 > freezing cans which contain a PFC gas would have as much effect on > climate change as a medium car over its whole lifetime (horrific > thought). Furthermore, there will still be the contents of two of those > cans in the atmosphere 40-odd generations from now (assuming man lives > for another 40 generations!). However, I think most freezing cans > contain HFC-134a, which is bad enough but not as bad as PFCs. Some may > still contain HCFC-22 which is just as bad AND an ozone depleter, to > boot, but is not phased out under the Montreal Protocol until 2010 (some > countries may phase it out sooner). > > Brian > > --------------------------------------------------------------------------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/html/forum.htm for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > ---------------------------------------------------------------------------------