I'm working on a sensor array project using MQ-2,3,4,5,6,8, and 135 sensors. The bulky breakout boards would unnecessarily increase the PCB size, and purchasing bare sensors is not a cost-effective option. How can I safely remove these sensors from their breakout boards without compromising their sensitivity?
A solder sucker is the way to go for desoldering through-hole components. I recommend this one specifically, personally.
While solder wick (aka solder braid) can be used, it's generally more suited for desoldering surface-mount components--it can have trouble wicking the solder out of a through-hole.
Another option is a desoldering station, which is basically a soldering iron combined with a vacuum pump. That's more expensive than just using a solder sucker with your existing iron, though. Hot air can also work, but you run the risk of damaging what you're trying to desolder, if it's temperature sensitive.
It can be done with solder braid or a desolder gun or a hot air soldering station.
Solder braid is used together with a solder iron, see link.
A desolder gun have a hollow tip that is put over the pin, and when solder have melted, it's sucked away with vacuum. The gun in the link uses compressed air through a nozzle that creates vacuum (Bernoulli's principle). Hakkos models uses a vacuum pump instead.
And finally, a hot air soldering / rework station, uses hot air. It's effective, both to de-/solder and to overheat components.
But there's one more way to do it, and that's with a thick copper wire. Bend it to the outer shape of the sensors pins, make sure it's not tight. Connect each and every pin to the wire with solder, and now heat the middle of the wire. A component usually drops from the PCB by it's own weight (take care if the sensor is sensitive to shocks), or it can be wiggled out.
