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Its time I cleaned out my closet and tore down all these old boards for their parts. I will not be willing to go the solder braid or bulb sucker method. How hot does a heat gun need to be to effectively drop these components from a board?
Should I aim for Power? (W) or Temp (F, C)?
I see some 1000W guns that go up to 1000F, but I've tried that same model before, and it didn't melt anything.
Then I see a 1500W gun. Looks promising... oh, wait. Its still only 1000F. How hot can I get for about $30?
Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
I got a cheap gun from the hardware store and it works great. I'm pretty sure it's less than 1000W. It melts the solder and catches the board on fire just fine. Make sure to do this in a well ventilated area as I don't and get a killer headache.
Registered Member #3040
Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237
Mads Barnkob wrote ...
i have yet not had success with using a heatgun , the board smokes and the component gets very hot without the part coming off.
Wrong technique then.I regularly do this sort of thing with this . The only adjustment the gun has is two speeds for the fan (which is useful) but I have used a single speed paint-stripper gun in an emergency before. The trick is to start with the gun a fair distance from the board and pre-heat it (on the lower fan setting if you have one), gradually bringing the gun closer over time. Every so often give the target chip a gentle tug, if it doesn't come off then move a bit closer. You can also tell when it's hot enough by placing a small amount of solder near the chip, when it melts pull the chip off. Note that none of the components around the IC I pulled off were disturbed in any way. Eventually you will get a gut feeling for how close to get the gun and for how long. As to the original post, spec. of the gun doesn't really matter, adjustable (both heat and speed) is a nice convenience though.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Martin King wrote ...
Mads Barnkob wrote ...
i have yet not had success with using a heatgun , the board smokes and the component gets very hot without the part coming off.
Wrong technique then.I regularly do this sort of thing with this . The only adjustment the gun has is two speeds for the fan (which is useful) but I have used a single speed paint-stripper gun in an emergency before. The trick is to start with the gun a fair distance from the board and pre-heat it (on the lower fan setting if you have one), gradually bringing the gun closer over time. Every so often give the target chip a gentle tug, if it doesn't come off then move a bit closer. You can also tell when it's hot enough by placing a small amount of solder near the chip, when it melts pull the chip off. Note that none of the components around the IC I pulled off were disturbed in any way. Eventually you will get a gut feeling for how close to get the gun and for how long. As to the original post, spec. of the gun doesn't really matter, adjustable (both heat and speed) is a nice convenience though.
Martin.
I have a 2 speed 2000W heat gun, the problem is through hole components containing plastic that melts long before the solder, even if its with some distance in legs to the board.
Newer PCB's also seem to be harder to de-solder due to lacquer or other films sprayed over it.
Small transformers in SMPS will start melting the former or the tape around it before the 8-16 legs are going loose.
Slow heating from a distance does not seem to make much difference for through hole for me
Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
i believe some of the newer boards use a conductive glue and not solder. That might be your problem. I've uses this method to salvage around 20 smps transformers without any damage to them at all. Same with FBT that are completely covered in plastic. They don't melt at all.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
I just attack the board with sidecutters. Using this method you can chop the components out, and cut what's left of the board between terminals, then hold the component in a crocodile clip stand and remove the remaining bits of board with a soldering iron and long nosed pliers. The only disadvavtage of this method, apart from the mess it makes, is that sometimes the legs get bent, but it does avoid the risk of overheating components.
Registered Member #3040
Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237
Mads Barnkob wrote ...
Newer PCB's also seem to be harder to de-solder due to lacquer or other films sprayed over it.
Small transformers in SMPS will start melting the former or the tape around it before the 8-16 legs are going loose.
Slow heating from a distance does not seem to make much difference for through hole for me
Remove any lacquer etc with solvent and a toothbrush/paper towel before attempting coated boards. I remove plastic connectors etc. using the same technique without melting them. I just shot a video this afternoon of me taking a chip of a scrap board note I switched the the gun to the higher speed near the end once I thought the board was pre-heated enough.
EDIT: And as for through hole, 64pin plastic connector on the edge of a multilayer board, same heat gun no heat shielding of the connector :-
No melted plastic, scorched board or lifted tracks.
You need to realise that the solder needs time to heat all the way through so too much heat applied too quickly will just burn the PCB/melt the connector you need to gently warm the whole area up around the part being removed to just short of the melting point and then bring the gun in close to melt the solder, if it doesn't melt in a few seconds, back the gun off and heat some more then bring it in for a few more seconds, repeat until the connector/ic etc. can be pulled off the board. NEVER keep the gun close to the board for more than a few seconds at a time and keep it moving to evenly heat the part. Another useful tick is to thread some wire underneath the part being pulled (not always possible) so you can use the wire to pull the part off the PCB.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
I use a heat gun that is 1200w and 1000F. That is fine if you want to get a part with many pins out or a few parts, but if i have numerous TV boards i heat the solder with the heat gun then blow the solder off with compressed air. It shoots solder everywhere, but that is not a problem if you do it outside. It works like a solder sucker. I guess a solder blower...
Registered Member #2941
Joined: Fri Jun 25 2010, 08:08AM
Location:
Posts: 143
I use to do that with a butane torch and I have a good tips :once you think the board is hot enough ,you slam the side of it on a table ,all the component who have reach the good temperature fly out of the board!
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Time for a heat gun
