How to Desolder Through-Hole Components

It's easy to make mistakes when soldering through-hole components. In order to correct them, it's best to completely remove all solder from the solder joint and start again. Desoldering can also be used to remove components from Printed Circuit Boards (PCBs) for use in other projects.

Difficulty: Moderate

Instructions

Things You'll Need:

• Soldering iron with a conical tip
• Solder sucker
• Solder wick
• Soapy water/rubbing alcohol
• Old toothbrush

1. Purchase a quality soldering iron with a conical tip. Though there are "desoldering irons" they're generally not needed. The same things can be done with a normal soldering iron, a solder sucker and good coordination.

2. Purchase a solder sucker and solder wick. A solder sucker is a spring-loaded vacuum pump. When you press down on the plunger and compress the spring, a notch will hold the plunger down. When you press the button, the spring will quickly extend and "suck" melted solder near the tip of the solder sucker into the chamber inside. Solder wick is a braided metal wire that is used to clean up excess solder on the surface of a PCB.

3. Heat up the soldering iron. Start heating the soldering iron several minutes before you begin desoldering, since it should be completely heated before attempting to desolder any solder joints. The exact amount of time it takes your soldering iron to heat will depend on your particular iron.

4. Clean the board from which you'll be de-soldering. Soapy water or alcohol and a toothbrush can be used to clean dust, corrosion or excess flux from the solder joints you'll be desoldering.

5. Tin the tip of the soldering iron. Apply a small amount of solder to the tip of the soldering iron, just enough to make it shiny, to aid heat conductivity and make it easier to melt the solder joints. Wipe the excess solder on a damp sponge.

6. Hold the soldering iron in your right hand and the solder sucker --with plunger already depressed-- in your left hand. If you are left-handed you'll need to reverse this.

7. Heat the solder joint. Gently press the tip of the soldering iron onto the solder joint. You should see the solder melt almost immediately. If it doesn't, your soldering iron is not hot enough. If it is as hot as it can get and it still doesn't melt the solder, then your soldering iron is not hot enough to melt the solder compound used to create the solder joint.

8. Suck the melted solder with the solder sucker while the soldering iron is still on the solder joint or at the same exact time you remove the soldering iron from the solder joint. If done correctly, a large amount of solder from the joint should have been sucked up into the solder sucker.

9. Remove the soldering iron from the solder joint.

10. Push the plunger of the solder down again. A small piece of solder should come out--be sure to put this in a small container. Many types of solder contain lead and should be disposed of correctly.

11. Wait a few seconds to allow the PCB and component to cool and repeat steps 7 through 11 until all of the solder is gone from the solder joint.

12. Heat the component lead one last time and move it with a pair of needle nose pliers. This will separate the component lead from the solder pad.

Tips & Warnings

• The solder joints should be as shiny as possible. Clean and shiny solder joints have better heat conductivity so it's easier to melt the solder.
• Once all solder joints of the component are desoldered, remove the component from the PCB.
• If you are going to solder a new component into this PCB, clean the solder pad up with the solder wick. Place the solder wick onto the solder pad and heat the opposite side of it with the soldering iron. The wick will heat up, melt the solder which will flow away from the still cold solder pad.
• If the joint does not immediately melt, do not continue to hold the soldering iron to the joint. This will only heat the PCB and component without melting the joint, possibly damaging both.

[AmandaMorin]

on 12/4/2008 You can desolder with just a wick--it really depends on the situation and how much you're willing to spend. Using solely wicks can get expensive. To desolder with the wick, try holding the wick to the tip of the iron for a few seconds to heat it before putting it over the solder joint. As for soapy water, I wouldn't recommend immersion, but a little on a toothbrush or sponge is manageable.

[Baffo32]

on 12/2/2008 Can I desolder with only solder wick and no solder sucker? How long it should take to heat up the solder wick enough to melt the solder? I can rapidly melt solder with my iron but cannot seem to melt it behind the wick. Is it all right to hold the solder to the wick against the pcb for a long time or will this damage the pcb? Is it really okay to clean the pcb with soapy water -- won't the water cause problems?