You need to desolder pins when replacing or salvaging components on a circuit board. Desoldering pins remove the connection/attachment to the circuit board. The most important consideration when desoldering pins is how to remove the molten solder that attaches pins. With this in mind, there are two main ways. First and foremost, you can use a desoldering pump. You can also use a desoldering braid or solder wick.
How To Desolder Pins Using a Desoldering Pump
Step 1: Identify the Pins in Question
The process begins with locating pins to be removed. A desoldering pump acts as a solder sucker (vacuums molten solder) to free the pin from the circuit board. Before you start, identify the pins to be removed by studying the circuit board carefully on both sides. This step is meant to isolate the pins in question to avoid disconnecting other parts.
A soldering pump is common when desoldering pins since it work best for such connections (through-hole connections). However, you can still use it for surface-mounted devices.
Step 2: Clean the Work Area and Soldering Iron
Before you start desoldering, clean your terminals. You can do this using a cloth, or soft brush dipped in some isopropyl alcohol. Most importantly, clean the terminals located on the soldered side only and not the component side.
Your soldering iron should also be cleaned at this point. This can be done by rubbing a sponge on the tip to remove debris.
Step 3: Heat Your Soldering Iron and Make Contact with the Soldered Pin
After cleaning your circuit board and soldering iron, proceed and heat the old solder using your soldering iron. The tip of the iron should make contact with the old solder continuously to melt it. This should be done while the desoldering pump is strategically placed to suck the molten solder. You can add some new solder on the old solder initially to have a sizable amount of molten solder to suck out.
Step 4: Suck the Molten Solder Out
The tip of your desoldering pump should be in contact with the molten solder without applying too much pressure. Activate the desoldering pump at the perfect time to suck out all the molten solder. The mechanisms of desoldering pumps differ. However, the most important factor is pump placement and timing since molten solder can harden quickly. You should focus on one pin at a time and strategically hold the desoldering pump with one hand and the soldering iron with the other hand.
Step 5: Repeat to Desolder All Pins
The above steps summarize the basics of how to desolder pins. You should repeat until you have desoldered all pins. Most importantly, don’t leave any old solder behind, as it can trickle to the next terminal.
If you encounter difficult pins, you may need to apply some desoldering tricks. If the molten solder has difficulties flowing, it helps to apply some flux first. As mentioned, adding some new solder to the old solder initially can help to create a better workable area. Once the new and old solder has mixed and hardened, it may be easier to suck it off. Lastly, you can wiggle pins in through-hole connections to break attachments to the sides.
Step 6: Clean Your Circuit Board
Finish by cleaning your board using a clean cloth/soft brush and some isopropyl alcohol. A resin cleaner can be used to remove resin on the solder pad, if any.
How to Desolder using a Solder Wick (Desoldering Braid)
You can use a desoldering braid instead of a desoldering pump. The braid or wick works by absorbing the molten solder from the pins and on the circuit board. There are critical tips on how to desolder pins using a solder wick. For instance, the braid in use shouldn’t be too large, or you risk burning your board. A large braid will also take longer to heat up.
What’s more, solder wicks aren’t the best for surface-mounted components. However, you can still desolder pins. The process can take more time and energy. However, a desoldering braid will get the job done. Lastly, it helps to learn how to properly place your solder wick. Other tips include using some flux on your braid to make it better at absorbing molten solder. However, most desoldering braids are sold with some flux.