These have a teflon tip, which is why they can take the heat.
The unit must be cleaned occasionally, to remove accumulated solder.
These are pretty cheap.
http://en.wikipedia.org/wiki/Desoldering_pump
You can also get a desoldering station, which consists of a vacuum pump,
leading to the tool head, which has a source of heat, plus a soldering tip
with the connection to the vacuum pump. That too has to be cleaned
frequently,
as the glass tube inside the tool head, clogs up with solder after a few
joints have been freed of solder. A filter in the vacuum path, prevents
stuff
from going down into the pump. This is a more expensive solution, and not
a casual purchase.
http://www.howardelectronics.com/jbc/images/LDIS-2A.jpg
This is another solution, but this is suited more to cosmetic cleanup,
after most of the fun is over. I use the thin stuff, like 0.050" wide
or so. I find the really wide solder wick to be too hard to get hot
enough. One trick to using this, is I compress the wick by rubbing
a smooth tool tip over the wick. The squashed wick sometimes picks up
a bit better. (You won't find the thin stuff at Radio Shack. I have
a solitary good electronics store in town, and that is the only place
I could expect to find the good stuff. Radio Shack is more like to
have the fat useless wicking braid.)
http://en.wikipedia.org/wiki/Solder_wick
One other poster here, a few years back, suggested ChipQuik. It is a low
temperature solder. The idea is, you add some of that low temperature
solder to each solder joint. Then, if you can apply moderate heat to
all the joints at the same time, you can get all the solder molten.
After the device has been physically removed, you can clean up the
lands carefully with solder wick. (An issue here, is the metallurgy.
The purpose of removing all the solder on the component surfaces, is
so when you use new solder, the consistency is appropriate for the
situation. You don't just plunk the new chip down and seat it in the low
temperature solder. I don't know what the long term reliability
implications would be for such a soldering job, if you didn't clean up
after using it.)
http://www.chipquik.com/instructions.html
When working on PCBs, you probably already know that some have poor
adhesion properties. On the PCBs at work, we had excellent physical
durability (one of our blank PCBs, cost as much to make for just
the PCB, as does a fully populated Chinese computer motherboard).
I could leave a soldering iron tip on one of our boards all day long,
and not lift a pad off. I've worked on a couple retail computer
boards, and have lifted two pads so far. The finish steps and materials
used in the board constructions, affect the durability and ability to
do repairs. If you see a small rectangular pad, all by its lonesome on
the surface of the PCB, that is the kind of thing that will "wipe" off
the surface of the board, if you apply pressure with the soldering
iron tip. It is a tricky balance between not using enough heat, and
bolstering your efforts by pressing on the work with the tip of the iron,
versus using too much heat, and simply frying the pad off the surface
of the board. It is one of the reasons they make soldering iron stations
with a temperature control knob and temperature readout, so you have
some idea what temp things are at.
In the picture here, you can see a Weller station, complete with
well worn sponge for cleaning the tip of the iron. A good unit has
an easy to use dial on the front, for adjusting the set point of the
tip. I don't have one of these for home use, but these were common
at work.
http://w3.externet.hu/~gylab/weller/weller2.jpg
In this example, you can see how to remove a large quad flat pack.
With a hot air rework station, plus a ton of expensive custom tools
with just the right dimensions for the various chip outlines, you can
uniformly heat up a chip until the solder is molten on all the pins.
The thing in the middle of the chip, is there to pull upwards on the chip
to free it from the board. This is the kind of thing, where "practice
makes perfect", and usually one person on staff has "recycled" enough
chips from boards to get good at it. I limited my activities to
soldering irons
http://upload.wikimedia.org/wikipedia/commons/5/5b/Desoldering_with_hot_air.jpg
It is even possible to handle chips on the bench, where the contacts
are hidden underneath the chip. Those chips are ball grid array.
Materials used at the factory, for a lot of soldering jobs, take
the form of "solder paste", which is screen printed onto the surface
of the PCB. That is part of the trick to getting the solder
to stick well. Soldering of big components will probably involve
a "profile", a defined temperature ramp for "preheat", a period
of time for "hold" at the peak selected temperature, followed
by a controlled cool down ramp. The trick to quality work here,
is X-ray inspection after the job is finished. While the defect rate
is low (one bad joint in 100000 balls), it still pays to X-ray, to
see if there are any voids or cracks or the like. Some computer chips
can have 1500 balls on the bottom, and doing a good job of soldering
those is not trivial.
http://en.wikipedia.org/wiki/Ball_grid_array
Here, you can see a manufacturer recommending how to solder a component.
This kind of information is mainly for encouraging good technique
at the factory. It is harder to get this kind of control on your
typical rework bench (if you have a limited budget).
http://www.triquint.com/prodserv/tech_info/soldering.cfm
The typical budget allows for the temperature controlled solder station
(with the ratty looking sponge on it, which you're supposed to keep wet),
a desoldering hand pump, a few rolls of wick, and a lot of cursing and
swearing. Keep a "swear jar" near the bench
Have fun,
Paul
.. Another suggestion I read somewhere was to use a