how to desoldering surfacemount IC??

[Lorenzo]

I'm looking for some tutorials on youtube that could explayn me how desoldering surfacemount IC.

Someone can halp me?

I found this video but comment are not so enthusiastics and referes about "hot air gun" ...
but I would like to desolder only few pins without brake them... I do not want to remove the IC completely.

anyway... I can't understand what the guy in the video is speaking about (I'm sorry for my english) so... what's the flux he is using? and what kind of "pen" is he using?

thank you in advance for your kindly reply.

[blue hell]

A hot air gun works very well. Another possible tool is the tweezer like soldering iron with rectangualr setup bits ... this stuff costs a bit though ... do you need the chip to go of intact? otherwise you could clip off the legs & then desolder the (remainders of the) legs one by one.

[Lorenzo]

[blue hell]

Ah ok, that clears it up ... not really easy I think ...

[crochambeau]

Can you loop a wire around the leg you wish to free up, then apply gentle (firm enough to lightly bend metal) pulling while at the same time applying heat with a tinned soldering iron?

Getting the wire threaded and secured to itself (so it won't bend first) may be a challenge.

I'd connect the wire to the chassis beforehand to assist in ESD practices.

Just a thought, albeit sort of a caveman approach.

[magman]

I've not done much SMD work, but I've got a few hints that may help explain the video you linked to.

Normal solder wire that we use for electronic purposes has a flux in it to help in the soldering process (it reduces oxide production and tends to lower the soldering temperature if I recall correctly). When you are re-working an existing circuit, you need to add flux to make the process work a bit better. You can get de-solder braid with flux included, but it will work better if you apply flux to the component before trying to de-solder it. Something like this would be a useful substitute I think:

http://www.rapidonline.com/Tools-Fasteners-Production-Equipment/Soldering-Equipment/Solder-Fluxes/Surface-mount-rework-flux/118294

Next, the "Pen" you mentioned is actually a pin, something metallic and small enough to get behind and underneath the pins you are trying to de-solder. If you listen to the video carefully, you will hear a slight clicking noise as he forces the pin under the IC pins, as it breaks each connection with the PCB. This also explains why he mentions about no forcing the pin, as the IC pin might not have been desoldered properly - if you force it, you might lift the pad off the PCB - which would be bad.

Just a few thoughts, but i hope this makes things a little clearer.

Magman

[Lorenzo]

[daverj]

A trick that I've used to lift a pin of an SMD part is to use a sharp pointed Exacto razor knife blade as a lever while heating the pin and melting the solder.

By putting the blade flat on top of the trace/pad and up against the tip of the IC pin, and then heating the pin with a soldering iron you can wiggle the razor knife blade and get it under the IC pin, lifting it a few thousandths of an inch.

Once you have lifted the pin this way you simply use solder braid to wick away the solder on the pad and you are left with a pin that is floating up in the air.

[Lorenzo]

[hexagon5un]

As Blue Hell suggested, a heat gun is good. There are some cheap options: butane pen torches or "craft" heater/blowers. Basically, just get everything up to a temperature that the solder is melting, then pull it off with tweezers.

I've seen people do it with a candle, although that's a little brave for my tastes.

A more straightforward approach is chip-quik and a soldering iron: http://www.chipquikinc.com/.

[forbin]

I had good luck with a heat gun for getting paint off. It cost about $20 from the hardware store. The trick that i found was to let the gun get hot, apply it to the other side of the board for a short while then to smack the board (whille still very hot) down on a hard surface and the momentum took my chip of really cleanly. I rotated the chip 90 degrees, soldered back on and all was well!

[Lorenzo]