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How to Remove Solder: A Guide to Desoldering Techniques

Circuit boards form the backbone of electronics by giving components a place to connect. Occasionally, extra globs of solder may hinder that, so desoldering becomes necessary. 

Often, when we desolder a component from a circuit board, we do this for three primary reasons: Either because of an upgrade or repairs or sometimes we want to make modifications. 

As a professional, you won't be able to achieve any of those if you don't know how to remove solder safely from a circuit board without destroying other components. 

Fundamentally, this article will walk you through everything you need to know to remove solder from any board project.

In this article, we'll cover quite a lot of ground on the following: 

● What is desoldering?
● Tools required to remove solder from circuit boards
● Different methods to remove solder from PCBs
● How to remove solder from circuit board holes
● How to remove old solder
● How to remove solder without wick
● How to remove solder flux

Sounds good? Let's get into the article. 

What is Desoldering

Solder is the material used to join electronic components together. Desoldering is the process of removing solder from electronic circuit boards. It is a first and foremost step towards the restoration.

Tools for Desoldering


When removing the solder from a circuit board, some special tools are necessary to provide precise, non-damaging separation of solders in the presence of different soldering joint configurations and various board types.

Here are some of the most common tools used for desoldering:

1.Desoldering Bulbs


These are little air pumps that you press to create suction. This suction is utilized to pull the solder that has melted and been placed on a circuit board. 

The desoldering bulbs are the most appropriate for small jobs or you can use them to take the solder from the sensitive components.

2. Removal Alloys


Removal alloys are special metals that melt at a lower temperature than regular solder. This makes it easier to take off solder and parts from a circuit board without damaging them. These alloys are mixed with the existing solder on the board. When heated, this mix melts at a lower temperature. This way, you can remove parts safely and quickly.

3. Desoldering Braids/Wicks


Desoldering braid, commonly called desoldering wicks, is the most used tool for removing solder. It resembles long and thin copper wires. When you place a desoldering braid on a melted solder joint and apply heat to it with a soldering iron, the melted solder will flow into the braid. This is because the copper strands are very thin and compact, which creates the force that pulls the solder in.

Desoldering braids are available in different widths so that you can select a suitable size for a particular task. The wider braids can hold more solder, so the latter is better for bigger jobs.


4. Desoldering Pumps


Desoldering pumps, better known as solder suckers, are yet another common tool. They are made of metal and have a spring inside and a nozzle at the end. The nozzle is placed near the melted solder joint, and the button is pressed to activate the spring, thus creating a vacuum that draws melted solder into the pump.

5. Heated Tweezers


Hot tweezers are just like regular tweezers except that they have heated tips that can get hot enough to melt solder. You use them to support a component as it is being soldered. Next, you will remove the part from the board.

A heated tweezer is a good one to use when dealing with components that are delicate or are very close to other parts of the circuit board.

6. Hot Air Stations/Heat Guns


The hot air stations and heat guns shoot very hot air that can be used to cover a larger area and melt the solder. This feature becomes useful when you need to remove several elements at the same time. You heat the whole area with the soldering iron to melt the solder all at once.

7. Desoldering Picks and Tweezers


At times, even upon melting the solder and then removing it with a braid or pump, a small amount of solder might still be left behind on the circuit board. Desoldering picks and tweezers are useful tools for getting rid of the broken solder pieces that remain after soldering and desoldering.

8. Capsule Thermal Vacuum and Pressure Systems


These are large, purpose-built machines used in factories and repair shops where operators need to remove a lot of solder from circuit boards. These machines heat up an entire circuit board at once to melt all the solder in one piece. 

Then, they heat the solder with a strong vacuum for fast removal. While some systems use blasts of air to wipe away any residual solder, others use other methods, such as ultraviolet light or chemicals.

Different Methods to Remove Solder from PCBs


Several approaches are available to facilitate the safe removal of solder from a printed circuit board based on the joint sizes, part density, and the extent of the removal process.

1. Braid Method


The specific steps of braid desoldering are:

Select Braid Size

Remember to be very careful when choosing a desoldering braid size. Choose a wick that pairs well with the solder joint size you are targeting. 
Generally, the wider braids work very well.

Use A Soldering Iron

Solder the hole in the joint that you want to remove and place the desoldering braid into it. Put the soldering iron tip right above the hole. The braid subsequently takes over the job of heat conduction to transmit it to the joint.

Choose Quality Braids

Apply only top-grade copper braids for the flux-cored wire to produce the quickest possible heat soak to melt the joints. The low-quality braid requires external flux to assist in wetting and prevent cold joints. This way you can also add more solder if the original volume is insufficient.

You Will Be Looking for Colors to Change

Melting of the joints causes silver-colored tin to be formed when the braid is heated and it starts to act as a capillary to absorb the melted metal into the fine mesh strands.

Remove the iron and then interweave them together.

Now, while the solder is still in its liquid state, remove the heat source and lift the braid at the same time. This way, the molten solder will be pulled completely away from the board and into the strand cores. Wait till it cools down before you throw it out.

2. Pump Method


The desoldering procedure involves a specific solder sucker or pump to remove the small melted portions. Manual vacuum suction probes are also very effective. It is a process that requires no soldering iron.
So, here are the steps for this method:

● Prepare the tool by priming the spring-loaded internal suction piston. Ensures full vacuum potential to extract even large melted pools rapidly.
● Heat the soldering iron tip until it is fully hot (around 3 minutes). 
● Place and hold the iron firmly on the surface needing desoldering, and keep heating until all joint solders liquefy.
● Position the solder sucker nozzle over the target molten joint, angle the tip beside the component, and then press the button to activate strong vacuum suction to remove the solder.
● Allow the extracted liquid solder in the tool barrel to cool and solidify fully before ejecting it into a waste bin for safe disposal before the next use.

3. Iron Method


This is similar to pump desoldering but uses a dedicated desoldering station iron with a built-in solder removal pump.

● Place a pre-heated electric desoldering iron precisely over the target solder joint. 
● Then, use the pump to instantly draw all liquefied solder away through the hollow heated tip, surrounded by a protective nozzle.

4. Heat Gun Method


It involves the steps below: 

● To enable direct access, you'll have to extract the target printed circuit board from its protective outer casing or enclosure.
● Then, position the board atop a flammable surface before you power up a handheld heat gun. Direct the high-temperature airflow from the heat gun nozzle at the solder areas intended for full removal.
● Visually inspect as the solder absorbs the heat. When it's adequately melted, the solder transitions to glossy silver fluidity.
● With the solder now in the molten phase, use the tweezers, picks, or other implements to gently wick or pull the flowing metallic material fully away from the board.

5. Hot Air Rework Station


This requires a commercial convection-powered hot air soldering rework station. Let's quickly go over the steps:

● Select an airflow nozzle sized appropriately to match the exposed board components and areas that need desoldering. You should use larger nozzles for broad surface rework.
● Activate the station heating element and aim the nozzle output toward target solder points from a proper distance.
● Keep the station temperature control higher than the melting point of the solder present to liquefy when hit by a convection stream. You can also adjust the fan airflow speed.
● Use a flux pen or syringe to coat intended solder joints, which facilitates melting when hot air contacts.
● As the solder warms to a glossy molten state, use the tweezers to remove it entirely from the board and discard it.
● For a water-soluble solder, gently rinse the result with distilled water and dry it fully before reapplying the power.

6. Compressed Air Method


To use this method, you'll need compressed air, a soldering iron, and protective eyeglasses.

Unlike other methods we've mentioned, you'll have to first put on face protection gear since spraying the air is abrasive. Then, heat up the target solder joint using iron. 

All that's left for you to do is just aim the compressed air nozzle at the liquefied joint. The air stream blows off molten solder.

7. Desoldering Tweezers


You could use heated tweezers or other types fitted into solder stations for this method. These are the steps:

● Turn on the tweezers and adjust the heat setting as needed. You can always add extra solder or flux to the joint for better contact.
● Position the hot tweezer tips on either side until the solder liquefies.
● Use edges to remove the resulting molten metal away.

How to Remove Solder from Circuit Board Holes


Occasionally, when you remove solder from a circuit board, some residue may be left inside the holes. These holes are where the wires or components go, and it's very important to get the holes clean so you can put in a new part. 

Here are two ways to do this:

1. Desoldering Pump


The desoldering pump tip, which is the smallest, has to be placed right over the hole. Now, heat up the hole with your soldering iron. When the solder is melted, pull the pump trigger and suck the molten solder out of the hole. You may have to do this several times until you have completely removed all of the solder.

2. Drill Method


Also, you can use a drill bit of very small size to clean the holes from solder but this should be the last resort because you can damage the circuit board. Pick out a drill bit that is a little bit bigger than the hole. Slowly over to the spinning bit into the hole.

To help remove the old solder, it is important to drill only for a short time and change the direction of the spin frequently. When the hole is cleared, use isopropyl alcohol to remove any remaining residue.

Generally, it is necessary to be very cautious when using either of these methods to avoid damaging the circuit board.

3. Desoldering Braid


Desoldering braids, also called desoldering wicks, are an excellent tool for removing solder from circuit board holes. If the hole is tiny, you'll need to cut the braid down so it fits.

Be sure to cut the braid long enough to reach the bottom of the hole. Once you have the right-sized piece, gently push it into the hole. Do not force it, or the braid could get stuck.

Now, heat the outside of the hole with your soldering iron. When the solder is melted, the braid will soak it up. Once the braid gets dark, it means it's full of solder. Replace it with a fresh piece and continue heating the hole until all the solder is removed.

4. Using Both Braids and Wicks 


Sometimes, it might be hard to remove all the solder from a hole using just a desoldering braid. If this happens, you can use a wide piece of desoldering braid on the outside of the hole. 

This will help remove most of the melted solder. Once you've removed as much as you can from the outside, insert a thin piece of flux-covered braid into the hole. Add some more heat and keep heating until the hole is completely clean.

Removing Old Solder


The solder joints may be good at their manufacture, but they can get dirty or damaged over time. This would make it harder for electricity to flow through the circuit board, and in the worst case, it might even stop the current completely.

Here are the steps on how to remove old solder safely without damaging the circuit board:

Step 1: Apply the new flux. The flux is a specific solution that allows the solder to adhere to the metal. Wipe the old solder joint with a thin coat of new flux using a small brush, which will clean the old solder and prepare it for the next step.
Step 2: Use a soldering iron. It is better to have a soldering iron with a small tip that will heat up the solder without damaging anything surrounding the area. You may also opt for a heat gun, which has a very hot air blowing capability.
Step 3: Remove the soldering off. After the solder has melted, place a desoldering braid (a strip of woven copper) on top. The braid will be dipped in the molten solder. Wait until the joint cools off to check the solder. If not, reperform the process with some fresh flux and a tidy section of the desoldering braid.

You must be careful while doing this to avoid damaging the circuit board or the components connected to it.

Step 4: Remove residues. When you have soldered out the old solder, some flux residue will remain. You should definitely clean up that solder before you apply the fresh one. To achieve this, squeeze a little bit of isopropyl alcohol on the corners of a small, soft brush. Carefully brush over the spot where the old solder was located, removing the remaining residue. This will ensure that the new solder is well bonded with the other components and achieve a good electrical connection. 

Finally, when the joint is completely clean, you can add a small amount of fresh solder to prepare it for the next component's attachment.

How To Remove Solder Without Wick


So, how exactly do you remove solder without wick? This is exactly how you do this: 

If you unexpectedly don't have a desoldering braid, don't panic. There are a couple of ways to remove solder from your board. The first alternative is to employ the thin wires within the network cable. 

Carefully pick a few of the single cords apart. Having prepared the wires, heat the solder joint on your circuit board with the soldering iron. On the other hand, the solder is melted, the wires are laid on top, and the solder soaks right up.

Another solution is to select a thin metal rod that doesn't melt when you touch the hot solder. Be very careful not to use anything that will definitely mix with the melted solder, like a penny. 

We suggest a stainless steel rod or a pencil lead. As in the past, let the solder on the circuit board heat up. When it liquefies, you can apply tweezers or a similar tool to your rod to move the melted solder.

How To Remove Solder Flux


While quality "No-Clean" fluxes minimize post-work cleanup, removing lingering sticky residues ensures optimal connections, adhesion, and aesthetics. 

Here's how to remove solder flux completely:

● After initial desoldering, gently sweep flux traces clinging to board surfaces with a dry stiff-bristle brush before washing to dislodge clumps.
● Next, apply a solder-safe cleansing solution like isopropyl alcohol or commercial flux removers to the remaining sticky areas. Allow it to react briefly.
● Brushes should be wetted with cleaners to scrub affected zones actively, then rinse away, lifting contamination with streams of fresh solution. Inspect closely under light.
● Allow boards to completely air dry overnight before replacing conformal coatings or resuming electrical service connections.
Evaporation mitigates any liquid pooling under components over time.

Conclusion


So, we've come to the end of our comprehensive guide to the key techniques you'll need to remove solder from printed circuit boards and components safely. 

It doesn't matter if you're repairing old boards, upgrading assemblies, or modifying existing layouts. Intelligent desoldering allows you to reconfigure electronics without damage. 

We took the time to cover specialized tools that can help you desolder joints, efficiently wick or drain away resulting liquid metal and best practices for systematic removal across unique scenarios you may encounter. 

Apply the methods mentioned here, and you'll be fine. If you have any questions or requests about desoldering, please feel free to contact us. 
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