Desoldering Caps With Hot Air.

[Techstar]

I am considering buying a Hot Air System for practice at de soldering flatpack chips. There are some nice ones for sale on e bay for around the 60 pounds mark. Do any of you guys use these for removing Caps and other small single components . I have noticed the PCB trace is easy to damage by lifting component when small amount of solder is still there, on some boards , do you think a re work station could help in making neater less damaging repairs when pulling components.

[diif]

Re: Desoldering Caps With Hot Air.

Perhaps if traces are getting damaged then the iron isn't hot enough or the solder isn't fully melting.

I sometimes use hot air but you have to be careful you don't move small components with too higher an air speed.

Not sure if its a figure of speech but there should be no pulling of surface mount components, just a gentle lifting.

[redwire]

Re: Desoldering Caps With Hot Air.

It's a good question - how best to de-solder smt electrolytic caps?

You have to heat up the long PCB pads, underneath the cap - so I don't see hot air working because the capacitor's body is in the way of the heat. I haven't tried hot air on a electrolytic yet.
Lately I use a soldering iron and a lot of heat. But still pads get ripped off.

[mariushm]

Re: Desoldering Caps With Hot Air.

It depends if you want to reuse the capacitor or not.

If you don't care about it, easiest way to remove a capacitor is to gently twist the smt capacitor back and forth a few times until the wires break. Then, a drop of flux on pads and a tip with fresh solder will remove the old tabs that are still soldered to the tabs.

See the procedure explained here, at 10:35 : https://youtu.be/p1zhfYHUIIY?t=10m34s or this one at 5:50 : https://youtu.be/3-5UsS49170?t=5m53s

If you care about them, just flux the tabs, add solder to the tabs, then keep touching each tab for a second or so with your soldering iron... once both tabs are hot enough, a gentle nudge will move the capacitor away from that location

-

You can desolder things with hot air gun, but imho hot air gun is best used for ceramic capacitors and resistors, or for small ICs in soic footprints or sot-223, dpak etc, stuff that has small pins. Wet the parts with flux (helps with heat transfer), use hot air gun, if needed drag a iron tip with fresh solder over the pins and you're basically ready to remove the part.

[Techstar]

Re: Desoldering Caps With Hot Air.

Thanks for your advice people.

[stj]

Re: Desoldering Caps With Hot Air.

trying to remove smd electrolytics without hot-tweezers is very hard and risky.
if you try to do one side at a time you lift pads, if you use air the cap explodes!!

i fucking hate those caps!

[ben7]

Re: Desoldering Caps With Hot Air.

Yeah, as STJ said, be careful! The caps can explode if you heat them up too much. Be sure to wear safety goggles.

-Ben

[Agent24]

Re: Desoldering Caps With Hot Air.

For SMD chip electrolytics, I just use two soldering irons as if they were a pair of hot tweezers. You need both hands,, but it works fine for me anyway.