Desoldering and It's Components

 Desoldering may be required for several reasons:

1. a component may have failed
2. a wrong part was installed
3. a design modification necessitates a change; or
4. if a board contains expensive components that can be salvaged.
   

Whatever the reason, there are three common techniques to remove solder from a joint: using a desoldering pump, a desoldering wick, or desoldering iron.

Regardless of the method used, if it is permissible to destroy the part during removal, then a lot of time and effort can be saved. For instance, using wire cutters to trim off all the pins of a through-hole IC so they can be removed individually makes the removal process much easier. In most cases, avoiding damage to the PCB is of paramount importance.

Solder Pump/Sucker: 

A desoldering pump is exactly what it sounds like: a pump that sucks up solder.
Usually the pump is spring-loaded and provides recoil when released. The four steps
below outline how to desolder a joint using a desoldering pump.
 

    

1. Prime the desoldering pump. This involves depressing the desoldering pump spring. The pump will click when correctly depressed.
2. Heat the joint from one side with the soldering iron tip. Wait 1-2 seconds until the solder begins to melt from the soldering iron heat.
3. Put the pump tip on the other side of the joint. Don't be afraid to actually touch the joint 
4. Press the desoldering pump spring-release button to suck up the solder.
5. This procedure should be repeated if the joint has a significant amount of solder. If done correctly the joint should eventually look as shown in Fig. 

Desoldering Braid/Wick: 

A desoldering braid removes solder from a joint using a technique known as “wicking". Desolder braid is a piece of material that sponges up molten solder by capillary action that draws solder away from the joint the braid. The following procedure outlines the basic steps involved in desoldering a joint using desoldering braid.

1. Place the desoldering braid over the joint
2. Press the desoldering braid onto the joint with the soldering iron tip. This will apply heat to the desoldering braid and the joint allowing the molten solder to flow.
3. Wait for the solder to melt. The solder should flow onto the braid and away from the joint 
4. Cut off the solder coated portion of the desoldering braid. There should be no copper visible in the portion that is removed braid is very expensive.