Hi John, I've never used the hot tweezers. I'm going to have to look into them. Normally, for desoldering, I use a narrower nozzle with an elevated temperature - usually between 280C and 350C. That blows the part completely off the pads just as soon as the solder flows, with little impact on adjacent components. For soldering, since I use a 240C leaded solder paste, i use a larger nozzle with slower air flow at about 245C-260C depending on what I'm soldering. Desoldering against a copper plane is always a problem regardless of the thermal pad's shape. I'd think you'd need a pretty hot set of tweezers to get a big 1210 sized tantalum off the board if there's a ground plane.
Bob ----------------------------------------------------------------- AE6RV.com GFS GPSDO list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info From: John Ackermann N8UR <j...@febo.com> To: time-nuts@febo.com Sent: Saturday, November 5, 2016 2:35 PM Subject: Re: [time-nuts] I love the smell of tantalum in the morning Either hot tweezers or a hot air rework station are the best/easiest ways to remove dead parts. But two fine-tip soldering irons will also work and are a lot cheaper. The idea is to heat both ends of the part at once, and when the solder flows, lift or flip the part off. Then, use some liquid flux and narrow solder wick to suck off the excess solder, and you should end up with nice smooth pads ready for the replacement part. The key thing to avoid damage is to make sure the solder is really flowing on both pads before you try to lift the part. Sometimes ground pads have enough thermal mass that it takes a while to get them hot enough. Be patient. Good luck! John ---- On 11/05/2016 03:12 PM, Tom Van Baak wrote: > See C13 in the attached photo. I need to replace some blown caps on a few > boards [1]. In one instance the cap got so hot it melted itself off the > board. Quiet convenient, actually -- it acts like its own fuse -- but I don't > think the 5071 designers had that clever feature in mind. > > Having not done SMT before, how should I do it with minimal risk to the very > precious PCB. Or, what equipment should I use this as a good excuse to buy? > > Thanks, > /tvb > > [0] http://www.imdb.com/title/tt0078788/quotes > [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.