soldering.

[tautech]

 What am I supposed to do to maintain my iron? Also, I saw that the cheap iron tip started tipping/rusting. Also the heating reservoir started to rust, I guess, due to the environment because the soldering iron is in a garage drawer. Is that normal?

Depending on the environment your iron lives in may determine the maintenance it requires.
The stainless barrel that retains the tip gets a lot of thermal cycling and some flux splatter so discolors with time.
It's not a concern unless you want it looking like the day you bought it. 
Most of the modern irons are now of stainless construction and rusting is not now such a problem.

Tips to heater element fit.
This is were you can get into trouble IF you don't change/remove the tip from time to time. The fit clearances can be small and failure to remove or change tips from time to time can result in a stuck tip that when attempting to forcibly remove it could result in a broken element. 
If your tips are a loose-ish fit you won't have a problem.
Some assorted tips I have don't bottom on the element when installed and the lock ring tightened, so they won't work unless you provide some way to bottom them firmly.
I have a second handpiece of which the tip retaining barrel is slightly shorter and that's my workaround for the tips that don't quite bottom onto the element. Mix and match. 

[Stuartambient]

I find tinning the tip once maybe twice a session along with using the brass sponge will keep your tips in good shape. If you use the damp sponge you only do a quick dab and wipe but go for the brass sponge and you'll never look back.

[nanofrog]

So, solder wick is best to buy branded and by application. Also it's better buying a RA or MRA one instead of no flux.

Definitely stick to top tier braid that contains flux. As per application, it comes down to the size of the pad/hole, as you have to match it just as you do a soldering iron tip.

Another topic I wanted to discuss has been anticipated: tip cleaning. What am I supposed to do to maintain my iron?

Tin the tip every few joints or so to keep it from oxidizing (you'll figure it out with practice). FWIW, brass wool, particularly that from Hakko (contains flux), does an excellent job. Works with solder alloys that are either lead based or lead-free (originally developed for lead-free, but does an amazing job with leaded as well). Sponges with distilled water still do well for lead based alloys as well. FWIW, if I'v a choice however, I opt for the brass wool.

We will talk about component placing (tweezers and other tools) later.

Plenty of threads on this type of thing if you search.  Otherwise, you'd be best to start a new thread. 

[R005T3r]

My garage is a humid and hot place, generally... Well is not that hard. Also in the station I'll have there's a brass sponge.

[continuo]

I used mine and got almost instant wetting using extra flux and a 850 series tip in my Metcal MX-500.

850 series? How hot get these, close to 500°C? You probably could braze with them... 

[GreyWoolfe]

I used mine and got almost instant wetting using extra flux and a 850 series tip in my Metcal MX-500.

850 series? How hot get these, close to 500°C? You probably could braze with them... 

The tip gets to be about 800F/427C.  The tip is too small for brazing!

[R005T3r]

Another thing I wanted to ask: how do you desolder BGA components? There's no way to acess the joints...   

[gblades]

Using a hot air rework station

[mariush]

You warm up the circuit board from the bottom, can be as simple as a hair dryer or a paint stripping gun or go somewhat pro and use infrared rework stations (google or check youtube for these words and you'll see plenty videos).
Just have to make sure the temperature is lower than solder melting temperature, don't want to desolder surface mounted components on the bottom of the pcb, and you want to warm up the board under the chip gradually.

Once you're up to a nice warm temperature you can add a few drops of liquid flux on the edges of the bga chip and use a hot air gun to warm the chip (make circles over the chip with the gun, don't keep it in one place to overheat the chip). With the aid of the heated pcb from the bottom, in a few seconds the bga chip should be loose enough that if you tap it with a tweezer or something, it would move on the bga balls and that's how you'll know you can lift it up)
 

[R005T3r]

Seems damn complicated to me...  Better to stick with basic stuff.... 

[janoc]

Another thing I wanted to ask: how do you desolder BGA components? There's no way to acess the joints...   

Like this, for ex:

Seems damn complicated to me...  Better to stick with basic stuff.... 

It is. BGA is nigh impossible to rework reliably unless you have the proper equipment for it. Smaller chips can be done using hot air, but the large 600+ ball monsters no way.

[Capa-Alpha]

Another thing I wanted to ask: how do you desolder BGA components? There's no way to acess the joints...   

Removal of any BGA is relatively easy ... you could get away with a high powered heat gun wand add a tin foil shield to protect the adjacent components. But removal is not the problem, resoldering is. It's really hard to line up all the solder balls underneath the BGA. Sometimes you can eyeball it using the pcb artwork, but if you are misaligned more than 40% off the pad, the board may initially test out fine - but during thermal cycling (that is, turning the repaired product off & on), the solder joints crack very quickly. So now a proper optical alignment system and placement accuracy becomes critical. Most of the optical alignment systems on rework stations use a prism to split the image so that you can superimpose the BGA solder balls over a an image of the pad area and align using X, Y and Theta micrometers. Then then new or reballed BGA is tenderly lowered onto the pad array by an ultra-precise placement system - It is the optics and placement accuracy precision that makes commercial BGA rework machines so expensive. Unfortunately, this level of capability is beyond the scope of the hobbyist, unless you just won the lottery!

Here's an example of a US $30K+ (it's one of the cheaper models) of PACE's production-oriented BGA rework machine here:

http://www.paceworldwide.com/products/area-array-bga-rework/bga-rework-systems/tf-1800-bga-csp-qfn-smd-rework-station

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