Desoldering Braid

All you need is Techspray desoldering braid (wick) and a soldering iron. Here are the basic instructions:

1. Place the braid over unwanted solder, preferably on the greatest solder build up so that it maximizes the contact of the braid to the surface area of the solder.
2. Next, place your iron tip over the wick at 45 degrees and allow heat to transfer to the pad. Molten solder will absorb into the braid.
3. Move the solder tip and braid as needed to remove all of the solder at one time. Careful not to drag the braid over the pads, which can scratch.
4. Once the braid is full of solder, you must trim the spent portion and move to fresh braid in order to pull more solder. Remove the iron and braid simultaneously to avoid soldering the wire to the board.

Yes, all you need is Techspray desoldering braid (wick) and a soldering iron. Here are the basic instructions:

1. Place the braid over unwanted solder, preferably on the greatest solder build up so that it maximizes the contact of the braid to the surface area of the solder.
2. Next, place your iron tip over the wick at 45 degrees and allow heat to transfer to the pad. Molten solder will absorb into the braid.
3. Move the solder tip and braid as needed to remove all of the solder at one time. Careful not to drag the braid over the pads, which can scratch.
4. Once the braid is full of solder, you must trim the spent portion and move to fresh braid in order to pull more solder. Remove the iron and braid simultaneously to avoid soldering the wire to the board.

Desoldering braid is available in various flux types depending on your cleaning process and other requirements:

1. Rosin – Rosin fluxed braid has the fastest wicking action but does leave behind residues that need to be thoroughly cleaned.
2. No-Clean – No-clean fluxed braid is ideal when cleaning isn’t practical or possible. After desoldering, the only thing that remains is a clear, non-ionic residue. For field work, when a thorough cleaning is more challenging, this is the type of braid to use.
3. Unfluxed – In a production or repair environment where the flux is specified and can’t be changed, or when an aqueous flux is needed, you can add your own flux to this type of braid. Unfluxed wick will not remove solder unless flux is added. Different types of fluxes are available in pen packaging, which is ideal for fluxing braid.

Desoldering braid or “wick” is a pre-fluxed copper braid that is used to remove solder, which allows components to be replaced and excess solder (e.g. bridging) to be removed. The soldering iron is applied to the wick as it sits on the solder joint, and when both are brought up to the solder's melting point, the flux is activated and, through capillary action from the braided design, solder is drawn up the wick.

No, not if your concern is only reliability problems from ionic contamination. No-clean flux contains minimal ionic material that is fully consumed when the flux is activated, or in other words, brought to soldering temperature. If all of the flux isn’t activated, like when you apply a lot of flux but only solder a small area, you still need to clean the PCB.

If you are applying conformal coating, you should remove all flux residues, regardless of the type of flux. Most people understand that when painting something, the surface must be prepared so it is absolutely clean. Otherwise, the paint will quickly lift off the surface and peel off. The same logic applies to conformal coating, even when the contamination is from no-clean flux.

Yes, rosin flux should be cleaned off of a printed circuit board (PCB) after soldering is completed. The following are the reasons to remove flux residues:

• Improve Aesthetic Appearance of PCB - If you are a contract manufacturer of PCB’s, the visual appearance of the board reflects on your work. A clear, greasy-looking residue around a solder joint may raise flags for your customer’s incoming QC inspectors. If the flux residue chars and forms spots on the solder joints, it may look like a true defect like a solder joint void or “blow hole”. If the flux residue is from a rework process, it acts as a fault tag in the rework area, calling attention to the work even if there shouldn’t be a concern.
• Improve Reliability of PCB - Reliability requirements are generally driven by the nature of the final product. For a disposable product like a computer keyboard, nobody loses their life if it stops working. In that case, an EMS supplier may use no-clean flux and forgo the cleaning process. On the other end of the scale, requirements for pacemaker electronics, where board failure could directly lead to death, are going to be much stricter. In that example, cleaning will be required after assembly and any subsequent rework, and the process will be thoroughly tested for effectiveness and repeatability. Long-life durable goods may fall somewhere in-between, with cleaning a requirement, but without the rigid testing and controls.
• Prevent Corrosion on Components and PCB - Flux residues left on electronic circuit boards are acidic. If they aren’t removed with a cleaning process, the residues can draw in ambient moisture from the air and lead to corrosion of component leads, and PCB contacts.
• Avoid Adhesion Problems with Conformal Coating - Most people understand that when painting something, the surface must be prepared so it is absolutely clean. Otherwise, the paint will quickly lift off the surface and peel off. The same logic applies to conformal coating, even when the contamination is from no-clean flux. “No-clean” refers to the amount of ionic material left after soldering. It has nothing to do with whether or not coating can stick to it. When there are flux residues left on the PCB before the coating process, it is common to see the coating lift or delaminate from the surface of the board. This is evident when the pockets are isolated around solder joints rather than the overall surface (the exception being the bottom of a wave soldered PCB). To make matters worse, coatings are generally semi-permeable, so breathe to a certain extent. Moisture can enter and soak into the flux residue, and potentially lead to corrosion.
• Prevent Dendritic Growth from Ionic Contamination - Polar or Ionic particles left from flux residue and other sources, when exposed to moisture from the ambient air and when current is applied, can link into a chain or branch called a dendrite. These dendrites are conductive, so form an unintended trace that cause current leakage or, over a longer period of time, even a short circuit.