How to Remove Solder from a Circuit Board Hole

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Why You May Need to Desolder holes

There are a few reasons why you might need to desolder and remove solder from holes on a PCB:

To replace a faulty or incorrect component
To modify or upgrade a circuit
To salvage components from an old board
To clean out holes for a new component installation

Whatever the reason, it’s an important skill to know how to properly desolder holes without damaging the circuit board.

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Tools Needed for Desoldering Holes

Before getting started, make sure you have the proper tools on hand:

Soldering iron
Desoldering wick/braid
Desoldering pump/solder sucker
Flux
Tweezers or pliers
Solder
PCB holder (optional but helpful)

Choosing the Right Soldering Iron Tip

Using the proper soldering iron tip is important for effective desoldering. In general, a wider chisel or hoof tip works best, around 2-3mm in size. This provides more contact area to melt solder quickly. Conical sharp tips are less ideal.

Desoldering Wick

Desoldering wick, also known as Desoldering Braid, is made of fine copper strands woven into a flat ribbon. It works by wicking up molten solder through capillary action. Desoldering wick is the preferred method for removing solder from holes.

Desoldering Pump

A desoldering pump, also called a solder sucker, is a spring-loaded vacuum pen that sucks up molten solder. It can be used in conjunction with wick or on its own. Pumps work best for cleaning larger volumes of solder, like from solder pots.

How to Desolder Holes with Wick

Follow these steps to desolder holes using desoldering braid:

Heat up your soldering iron to around 300-400°C (572-752°F). Exact temperature depends on the type of solder.
Place the end of the wick onto the soldered hole you want to clean.
Touch the soldering iron onto the top of the wick, sandwiching it between the iron and the hole. The heat will melt the solder and the wick will absorb it.
Slowly drag the wick and iron together along the hole to pick up all the solder. Add a little pressure to maintain good contact.
Lift the iron straight up and away, pulling the wick with it. The solder should come out of the hole stuck to the wick.
Snip off the used end of the wick with cutters, then repeat the process if needed to remove any remaining solder.

Tips:
– Apply a little flux to the wick to help it absorb solder more effectively
– If the solder isn’t melting, your iron may not be hot enough, or there may be grime inhibiting heat transfer. Clean the tip and try again.
– Be patient and let the wick do the work. Aggressive scrubbing can damage the PCB.

How to Desolder Holes with a Pump

Desoldering pumps can be used alone or in combination with wick. Here’s how:

Heat up your soldering iron to the appropriate temperature for your solder type.
Position the tip of the iron on the soldered joint you want to desolder. Let it melt the solder completely.
Quickly move the iron aside and place the nozzle of the desoldering pump onto the hole.
Release the plunger on the pump to suck up the molten solder. You may need to repeat this process a few times.
If there is still solder remaining in the hole, use desoldering wick to remove the rest as described in the previous section.

Tips:
– Make sure the pump nozzle is clean and free of blockages
– Hold the pump perpendicular to the board for the best suction
– Practice your timing between melting the solder and triggering the pump
– Empty the pump reservoir frequently to maintain suction strength

Cleaning Up Desoldered Holes

After removing the bulk of the solder, there may still be some residue or small bits left behind. Here are some methods to clean the holes more thoroughly:

Use a fine pick or tweezers to carefully scrape out any remaining solder
Apply flux and use the soldering iron to re-melt any bits, then wick it up
Gently twist a small drill bit by hand to clear the hole (go slowly to avoid damaging the PCB)
For stubborn holes, apply a little fresh solder and try desoldering again
Swab the hole with isopropyl alcohol to remove flux residue

The goal is to get the holes completely clean so new component leads can be easily inserted and soldered.

Tips for Desoldering Success

Go slowly – Desoldering requires patience. Rushing can result in Lifted Pads or damaged PCBs.
Use flux – Flux helps the solder melt and flow more easily for better removal.
Keep your iron clean – A clean soldering iron tip provides better heat transfer and control.
Match your tip to the job – Use a tip size appropriate for the holes you’re desoldering. Larger tips for bigger holes.
Apply even heating – Heat the joint thoroughly before trying to remove solder to minimize stress on the PCB.
Maintain your tools – Clean pumps, replace wick, and re-tin soldering iron tips regularly for best results.
Protect your PCB – Support the board in a holder and avoid pulling or prying. Let the tools do the work.
Know when to stop – If a hole isn’t coming clean, take a break and reassess before continuing to avoid damage.

With practice and the right techniques, desoldering holes becomes easier and faster over time.

FAQs About Desoldering Holes

What is the easiest way to desolder holes?

For most through-hole desoldering jobs, using desoldering wick/braid is the simplest and most effective method. It is inexpensive, widely available, and relatively easy to use with a little practice.

Can I desolder holes with a regular soldering iron?

Yes, a standard soldering iron is the main tool used for desoldering holes. The key is having the right tip for the job – usually a wider, blunter shape rather than a pointed tip. You’ll also need desoldering wick and/or a desoldering pump to remove the solder once molten.

What temperature should I set my soldering iron to desolder?

The ideal soldering iron temperature for desoldering varies based on the type of solder you’re working with. In general, a temperature between 300-400°C (572-752°F) works well. Leaded solder melts at a lower temperature than lead-free solder. Start lower and increase temperature as needed if the solder isn’t melting.

How do I desolder a hole without damaging the PCB?

To minimize the risk of damaging the PCB while desoldering:
– Apply heat evenly and thoroughly before trying to remove solder
– Let the tools do the work – avoid aggressive scrubbing or prying
– Support the PCB in a holder to prevent flexing
– Work slowly and patiently
– Stop if you encounter significant resistance and reassess

What should I do if there is still solder stuck in the hole?

If you’ve wicked and sucked but there are still bits of solder remaining in the hole, you have a few options:
– Use flux and the soldering iron to re-melt the solder, then try wicking again
– Scrape out the bits carefully with a pick or tweezers
– Apply a little fresh solder and try desoldering the whole joint again
– Gently twist a small drill bit in the hole to clear the solder (go slowly)

If the solder still won’t budge, it’s best to stop and evaluate your approach before risking damage to the board or pad. With patience and practice, even stubborn solder can usually be removed.

Conclusion

Desoldering holes is a key skill for anyone who works on PCBs and electronics. Using the tools and techniques covered here, you should be able to confidently clean any size hole and solder joint. Remember to work patiently, use the right tools, and stop if you encounter resistance to keep your boards in good shape. With a little practice, desoldering becomes just another part of the PCB Assembly and repair process.

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How to Remove Solder from a Circuit Board Hole

Why You May Need to Desolder holes