Electronic Repair

TraceTech No-clean Flux Pen is formulated to perform at the elevated temperatures of lead-free soldering but is also effective for tin-lead soldering as well. It's designed with a low surface tension to prevent bridging. Post-soldering cleaning is optional because the light residue left after soldering is barely noticeable is non-corrosive and halide free. Flux pens are an excellent way to dispense flux for benchtop soldering. You just hold the pen vertically and briefly depress the tip to start the liquid flow. This will saturate the tip of the pen with flux. Draw flux on the area to be soldered. Gently press the tip again when more flux is needed to keep the tip damp with flux.

A common method of repairing a broken trace is to solder on a jumper, which is basically a wire bypass around the broken trace. This can be time-consuming and visually unappealing. Techspray offers TraceTech Conductive Pen, which contains highly conductive silver suspended in a liquid polymer. This pens allows you to literally redraw the trace.

Techspray offers the TraceTech Conformal Coating Remover Pen that allows you to remove a tight area of coating around a repair area without affecting the rest of the PCB. You first saturate the tip by tapping it lightly on a surface, which opens the valve and releases solvent. Holding the tip down may oversaturate it, which could lead to solvent flowing into unintended areas.

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.

The most common way to clean flux residues from a repair area is to saturate a cotton or foam swab with isopropyl alcohol or another cleaning solvent, and rub it around the repair area. While this may be adequate for no-clean flux, where the goal is a visually clean PCB, this may not be clean enough when more heavily activated fluxes are involved, like RA or aqueous. The dirty little secret is that flux residues will not evaporate along with the solvent. You may dissolve the flux, and some of the residues will soak into the swab, but most of the residues will settle back onto the board surface. Many times these white residues are more difficult to remove than the original flux. One quick and easy improvement to this process is to rinse the board after swabbing around the repair area. While the solvent is still wet, spray over the entire board with an aerosol flux cleaner. Hold the PCB at an angle to allow the solvent to flow over the board and run off, along with any residues that are picked up. The straw attachment that comes with aerosol flux removers is a good way to increase the spray force and penetrate under the components. Some aerosol flux removers come with a brush attachment. The cleaning solvent sprays through the brush, so agitation can be increased by scrubbing while spraying. To absorb the flux residues, a lint-free poly-cellulose wiper can be placed over the repair area, and the spraying and scrubbing can occur over the material. Then remove the wipe and brush attachment, and spray over the board for the final rinse.

There is no way to give a definite answer for all circumstances, because safety is highly dependent on the amount voltage and amperage as well as environmental factors such as the equipment, working environment, etc. On the other hand, choosing a contact cleaner with high dielectric strength or breakdown (also called withstand) voltage increases safety when you do have to clean energized equipment. BEFORE you start spraying, we strongly recommend you shut down power to avoid the potential of sparks, electrical shorts or discharges, and other safety hazards. If, for whatever reason, you don’t have the option of disconnecting the power, look for electrical contact cleaners with a dielectric strength above 30 kV (30,000 volts). Choosing a nonflammable cleaner would also add a layer of safety in case there is a spark.

Whether or not conformal coating is required depends on the environment the electronic device will operate in, the reliability requirement of the device, and the cost of failure, whether in dollars or human lives. Typical consumer devices are generally not coated because cost is one of the top driving factors, and a coating step certainly adds to that. Devices operating in harsh environments may require coating, and the type of stresses and contamination will point to the best option, whether that is acrylic resin (AR), silicone resin (SR), urethane resin (UR), or some other type of protection. Aviation, aerospace, and medical devices often require coating because of the mission critical nature of these applications.