In article m.net,
Hamad bin Turki Salami wrote:

I have a board that I need to add a diode to. The problem is that
the diode is coming off another board that I've cannibalized for
parts, and I don't know how to get the diode off that board. I
know very little about this stuff. I've removed components before
using an ordinary soldering iron and a solder pump. However,
this diode is tiny and surface mounted, which seems to make things
a bit harder. I tried applying a soldering iron to the leads while poking
at the diode with a metal probe. Eventually, I cracked the diode
this way. Fortunately, the board has a few more identical diodes, so I
have another few shots at this.

Is there a trick to it?

I don't know what the quality of your equipment is, or your skill level
with a soldering iron. But, the *best* way to do this is to use an SMD
removal tweezer, which heats both ends simultaneously. Failing that:

1) An appropriately sized soldering tip, properly tinned. If it isn't
shiny, throw it away and get a new tip.

2) Rosin flux, as another respondent said.

3) Solder wick, as was suggested. "soder wick" (sic) is the best brand
name.

4) Put a generous drop of flux on the thing, and wick up as much solder
as possible. If your technique is correct, this will take no longer than
one or two seconds per end.

5) With fine tipped needle nose pliers, rotate the component to snap the
part loose from the tiny amount of solder still holding it to the board.
Lifting one end sometimes works, and sometimes breaks the end cap.
That's why I like the twist. If you need more than an inch pound or two
(wild ass guess) of torque, you didn't wick up enough solder.

If the diode is very small, you can skip the solder wick, use the flux,
heat both ends simultaneously by laying the tip parallel to the
component, and flick it off the board.

Note that low powered or low temp soldering irons are useless. Get a
decent iron and crank it up to 800. You can solder or desolder with
*much* shorter dwell times, exposing the component to far less heat than
using an underpowered iron and holding it on there for five or ten
seconds. Soldering small components shouldn't take any longer than
blowing out a candle.